[top]
000
FXUS66 KOTX 200423 AAA
AFDOTX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SPOKANE WA
923 PM PDT FRI SEP 19 2008
.SYNOPSIS...
A DEEP UPPER SYSTEM WILL MOVE BY TO OUR SOUTHEAST...OVER THE NEXT
DAY OR TWO...RESULTING IN DRASTICALLY COOLER CONDITIONS...AND RAIN
...ACROSS A LARGE PORTION OF THE INLAND NORTHWEST. SLIGHTLY BELOW
NORMAL TEMPERATURES WILL PREVAIL THROUGH NEXT WEEK.
&&
.DISCUSSION...
NO MAJOR FCST UPDATES SO FAR...AND NONE EXPECTED ATTM. THE
CHALLENGE WILL BE DETERMINING HOW FAR N INTO ERN WA THE CURRENT
NW-SE ORIENTED BAND OF PCPN STRETCHING FROM SRN WA...TO NE OREGON
AND SW ID REACHES. THIS IS THE FIRST BAND GENERATED ON THE E SIDE
OF THE UPPER LOW NOW OVER NRN CALIF. A SECOND VERY SIMILAR BAND
STRETCHES FROM CNTRL OREGON TO NW NV. EACH OF THESE FEATURES ARE
TIED TO EMBEDDED VORT MAXES ROUNDING THE BASE OF THE TROF...AND
EACH SHOULD WEAKEN AS THE MAXES LIFT NE INTO STRONGLY DIFLUENT
STEERING FLOW. IT IS THIS SECOND SRN BAND THAT WILL BE THE MAIN
PLAYER FOR SAT/SAT NT THAT WILL PRODUCE A DECENT RAINFALL OVER N
ID. WE`LL KEEP LOW TO MEDIUM-RANGE PCPN CHANCES IN THE FCST FOR
THE REST OF THE NIGHT FOR SERN WA AND ADJACENT ID PANHANDLE ZONES...BUT
NOT BRING THIS PCPN MUCH FARTHER N GIVEN THE STILL DRY LOW-LEVELS
AND OVERALL WEAKENING OF THE BAND. AND THOUGH A WELL- DEFINED
MESO- VORT MAX ON THE REGIONAL MOSAIC RADAR LOOPER IS TRACKING
BETWEEN KBNO AND KPDT...THE STEERING FLOW REMAINS SOUTHEASTERLY.
EMBEDDED THUNDER WILL BE COMMON FOR NORTHEAST OREGON...AND WILL
HAVE TO BE WATCHED CLOSELY AS IT REMAINS ADJACENT TO THE LEWISTON
AND CAMAS PRAIRIE ID ZONES. BZ
&&
.AVIATION...
A STORM SYSTEM MOVES FROM NORTH CA TO EAST OR/SW ID BY 00Z
SUNDAY...WITH MOISTURE DEEPENING FROM THE SSW. VFR CONDITIONS
EXPECTED AT ALL TAF SITES THROUGH 06Z SUNDAY...BUT LOOK FOR AN
INCREASE AND LOWERING OF MID AND HIGH CLOUDS. AFTER 18Z LCL MVFR
CIGS DEVELOP AFTER OVER SE WA/CENTRAL ID AS THE SYSTEM
APPROACHES...WITH RAIN BECOMING INCREASINGLY LIKELY. CIGS LOWER AND
RAIN CHANCES INCREASE OVER THE KGEG-KCOE CORRIDOR TOWARD SAT PM
(20Z-06Z). EXPECT MTN OBSCURATIONS AFTER 18-21Z SATURDAY. VFR
CONDITIONS EXPECTED TO PREVAIL OVER WRN TAF SITES (KMWH-KEAT)...WITH
ONLY A PASSING RISK FOR RAIN ATTM. BZ
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 58 69 50 62 47 60 / 0 30 80 50 10 20
COEUR D`ALENE 54 70 49 60 46 59 / 0 30 80 70 20 30
PULLMAN 52 66 47 63 46 60 / 20 50 70 30 20 30
LEWISTON 61 70 55 67 52 66 / 30 60 60 10 20 20
COLVILLE 46 73 45 65 41 62 / 0 10 60 30 20 20
SANDPOINT 47 71 46 58 44 56 / 0 20 80 80 30 30
KELLOGG 54 69 49 56 45 55 / 0 50 80 80 50 50
MOSES LAKE 57 74 49 72 47 69 / 10 20 10 10 10 10
WENATCHEE 58 73 52 71 50 63 / 20 20 10 10 10 10
OMAK 51 76 48 73 46 65 / 0 10 20 10 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
[top]
000
FXUS66 KPQR 200353
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
900 PM PDT FRI SEP 19 2008
.SYNOPSIS...AN UPPER LEVEL LOW PRESSURE AREA OVER NORTHERN CALIFORNIA
WILL WEAKEN TO AN UPPER LEVEL TROUGH AND MOVE INTO SOUTHERN OREGON
TONIGHT. ANOTHER WEAK LOW PRESSURE SYSTEM FROM THE GULF OF ALASKA
WILL BRUSH BY THE NORTH PART OF THE FORECAST AREA SATURDAY AND COULD
PRODUCE SOME LIGHT PRECIPITATION NEAR THE NORTH COAST SATURDAY. THAT
SYSTEM WILL KEEP DIGGING SOUTH INTO THE FORECAST AREA BRINGING A FEW
SHOWERS TO THE AREA THIS WEEKEND AND EARLY NEXT WEEK WITH THE BEST
PROSPECTS OF MEASURABLE PRECIPITATION LATE SUNDAY INTO MONDAY IN THE
NORTH PART OF THE FORECAST AREA.
&&
.SHORT TERM...INFRARED SATELLITE IMAGERY SHOWS AN UPPER LEVEL LOW
PRESSURE AREA CENTERED NEAR 41N 122W OVER NORTHERN CALIFORNIA MOVING
NORTHEAST. MOSTLY MID/HIGH CLOUDS ROTATING AROUND THE CENTER AND OVER
THE FORECAST AREA THIS EVENING ARE BRINGING LIGHT SHOWERS TO THE
CASCADES. THE LOW ALOFT WILL WEAKEN TO A NEGATIVE TILT DIFFLUENT
UPPER LEVEL TROUGH AS IT MOVES NORTHEAST TONIGHT WITH SOME SHOWERS
CONTINUING OVER THE CASCADES.
A WEAK UPPER LEVEL SHORTWAVE WILL MOVE ACROSS THE FORECAST AREA
SATURDAY WITH LOW CHANCES FOR SHOWERS OVER THE NORTHERN COASTAL
ZONES.
A MORE ENERGETIC UPPER LEVEL TROUGH WILL DIG INTO THE FORECAST AREA
SUNDAY INTO MONDAY WITH BETTER POSSIBILITY OF SHOWERS...EXPECT THE
BEST PROSPECTS OF MEASURABLE RAIN ON THE NORTH COAST/COAST RANGE AND
WILLAPA HILLS WITH THAT WEATHER SYSTEM. LIKENS
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...LONG RANGE
MODELS CONTINUE TO SHOW A LOT OF VARIABILITY IN THE EXTENDED TIME
PERIOD. THE 12Z RUN OF THE GFS INTRODUCES A CUT-OFF LOW SLIDING
THROUGH OUR AREA TUESDAY INTO WEDNESDAY...WHICH IS OUT OF PHASE WITH
PREVIOUS RUNS AND CURRENT THINKING. HAVE KEPT FORECAST MORE IN LINE
WITH PREVIOUS RUNS OF GFS AND ECMWF FOR TIME BEING UNTIL ALL MID
RANGE MODELS BEGIN TO SHOW SOME AGREEMENT. SHOULD SEE MODERATE
TEMPERATURES AND CLOUDY SKIES THROUGH MUCH OF THE LATTER HALF OF NEXT
WEEK. BROWN
&&
.AVIATION...AN UPPER LEVEL LOW MOVING EAST ACROSS NRN CALIFORNIA
WILL CREATE +10000 FT SCT-BKN CLOUDS NORTH OF ROUGHLY A LINE FROM
TILLAMOOK TO WILLAMETTE PASS THROUGH 12Z TONIGHT. EXPECT MARINE
STRATUS TO REDEVELOP AFTER MIDNIGHT TONIGHT...WITH MVFR CIGS AT KAST
AND A MIX OF IFR/LIFR FOG AND STRATUS AT KONP. COASTAL SITES RETURN
TO VFR SAT AFTERNOON. INLAND...EXPECT MVFR CIGS AT KPDX...KTTD AND
KHIO AFTER 13-14Z. INLAND SITES RETURN TO VFR LEVELS BY 19-20Z.
COULD SEE SOME CIGS AT KSLE AS WELL...BUT REALLY NOT EXPECTING TO
SEE MUCH SOUTH OF ABOUT AURORA.
KPDX AND APPROACHES...VFR CONDITIONS WITH HIGH CLOUDS THROUGH APPROX
12Z TONIGHT. 75 PERCENT CONFIDENT IN MVFR CIGS AFTER BETWEEN 13-19Z
SAT MORNING...LIFTING TO VFR AFTERWARD. DALTON
&&
.MARINE...NO CHANGES...PREV DISCUSSION FOLLOWS. WEAK HIGH PRESSURE
OVER THE COASTAL WATERS WILL CAUSE LIGHT WINDS/SEAS TO CONTINUE INTO
SAT WITH SWELLS AT AROUND 5 FEET. AFTERWARD SEAS SEAS SHOULD LOWER
TO LESS THAN 5 FT. THIS LIGHT SWELL IS ALLOWING THE COLUMBIA RIVER
BAR TO REMAIN FREE OF ADVISORIES DESPITE THE STRONG ASTRONOMICAL
EVENING EBB CURRENTS THIS WEEK. INCREASING NW WINDS/SEAS LIKELY
LATER SUN NIGHT AND MON AS HIGH PRES BUILDS IN BEHIND A WEAK GULF OF
ALASKA COLD FRONT. WS/DALTON
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR/WA...NONE.
&&
.PRELIMINARY POINT POPS (PROBABILITY OF MEASURABLE PRECIPITATION)
AST 122222 PDX 111221 SLE 111221 EUG 111221
2
$$
MORE WEATHER INFORMATION ONLINE AT...
Http://weather.gov/portland
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
[top]
000
FXUS66 KSEW 200348
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
845 PM PDT FRI SEP 19 2008
.SYNOPSIS...ONSHORE FLOW WILL CONTINUE OVER THE WEEKEND WITH A
CHANCE OF SHOWERS AS A SERIES OF UPPER LEVEL TROUGHS PASS THROUGH
THE REGION. AS A RESULT EXPECT THE CLOUDY CONDITIONS TO CONTINUE
WITH TEMPERATURES BELOW NORMAL. ANOTHER SYSTEM WILL AFFECT WESTERN
WASHINGTON EARLY NEXT WEEK WITH WIDESPREAD RAIN POSSIBLE.
&&
.SHORT TERM...UPDATED THE GRIDS AND FORECASTS AS SOME LIGHT SHOWERS
SPRANG UP...ASSOCIATED WITH AN UPPER LEVEL LOW OVER OREGON. RADAR
SHOWS SCATTERED SHOWERS HEADING NORTH...SO NEARLY EVERYWHERE HAS A
CHANCE OF SHOWERS. LEFT THEM OUT OF THE COAST WHERE IT IS NOT EVEN
COMPLETELY CLOUDY YET.
BOTH THE GFS AND EURO KEEP DRIBS AND DRABS OF PCPN ON SATURDAY...
THEN PERHAPS CONSOLIDATE INTO A TROUGH ON SUNDAY. KEEPING CHANCE
POPS THROUGHOUT FOR NOW. ZONAL FLOW ALOFT WITH ONSHORE SURFACE FLOW
WILL KEEP CLOUDS OVER THE AREA AND TEMPS ON THE COOL SIDE. BURKE
.LONG TERM...PREVIOUS DISCUSSION...LOW CONFIDENCE IN THE FORECAST
TUESDAY AND BEYOND AS BOTH THE GFS AND ECMWF DISAGREE ON TIMING OF
NEXT SYSTEM...WHICH IS CURRENTLY LOCATED BACK ALONG 40N AND 165W. SO
FAR THE GFS IS FAVORING A FASTER SOLUTION WITH A 1000MB SFC LOW
DEVELOPING OFFSHORE AND STRONG WAA/WARM FRONTAL PRECIP CLIPPING THE
AREA BY TUE. THE ECMWF IS MUCH MUCH SLOWER WITH THIS SYSTEM...WHICH
SHOWS IT STILL OUTSIDE 130W BY 00Z WED. BOTH SOLUTIONS REMAIN OUT OF
SYNC THROUGH THE END OF THE WEEK SO WILL NOT MAKE ANY DRASTIC
CHANGES TO THE FORECAST YET. 33
&&
.AVIATION...WEAK SOUTHERLY FLOW ALOFT WILL CONTINUE OVER WESTERN
WASHINGTON TONIGHT AND SATURDAY...AS AN UPPER LOW OVER NORTHERN
CALIFORNIA SWINGS INTO SOUTHERN IDAHO. WEAK ONSHORE FLOW AT THE
SURFACE WILL PERSIST. THE AIR MASS OVER THE FORECAST AREA IS
GENERALLY MOIST AND STABLE BELOW 3500 FT AND SOMEWHAT MOIST AND
WEAKLY UNSTABLE ABOVE 3500 FT.
A BAND OF LIGHT SHOWERS OR DRIZZLE EXTENDING FROM THE EASTERN
OLYMPIC MOUNTAINS ACROSS THE NORTH PUGET SOUND AREA AND INTO THE
NORTH CASCADES WILL MOVE NORTH AND WEAKEN TONIGHT. ANOTHER BAND OF
LIGHT PRECIPITATION FURTHER SOUTH...CURRENTLY FROM CENTRAL LEWIS
COUNTY INTO THE SOUTHERN CASCADES...WILL ALSO MOVE SLOWLY NORTHWARD
TONIGHT. CLOUD BASES OVER MUCH OF THE WESTERN WASHINGTON INTERIOR
ARE IN THE 2000-3000 FT RANGE THIS EVENING...AND THEY WILL GRADUALLY
LOWER OVERNIGHT TO AROUND 1000 FT WITH AREAS OF IFR VISIBILITY AND
CEILING. CONDITIONS WILL GRADUALLY IMPROVE SATURDAY MORNING BECOMING
GENERALLY BKN030 BKN050 SATURDAY AFTERNOON.
KSEA...VARIABLE MAINLY NORTHWEST WIND 0-5 KT THIS EVENING...BECOMING
SOUTHERLY AFTER MIDNIGHT...THEN SOUTHWEST 3-7 KT SATURDAY. EXPECT
IFR CEILINGS AND POSSIBLY VISIBILITY ROUGHLY 11Z-17Z. MCDONNAL
&&
MARINE...WEAK UPPER TROUGHS WILL MAINTAIN WEAK ONSHORE FLOW ACROSS
THE AREA THROUGH SUNDAY. ONSHORE FLOW WILL LIKELY INCREASE SOMEWHAT
LATE SUNDAY THROUGH MONDAY IN RESPONSE TO A SOMEWHAT STRONGER UPPER
TROUGH MOVING THROUGH. HIGH PRESSURE WILL SETTLE OVER WASHINGTON ON
TUESDAY AND THE FLOW WILL TURN WEAKLY OFFSHORE AHEAD OF AN
APPROACHING PACIFIC FRONTAL SYSTEM.
I WILL END THE SMALL CRAFT ADVISORY FOR TONIGHT AS ONSHORE GRADIENTS
REMAIN QUITE WEAK.
MCDONNAL
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...NONE.
&&
$$
000
FXUS66 KOTX 192315 AAA
AFDOTX
AREA FORECAST DISCUSSION...UPDATED AVIATION DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
415 PM PDT FRI SEP 19 2008
.SYNOPSIS...
A DEEP UPPER SYSTEM WILL MOVE BY TO OUR SOUTHEAST...OVER THE NEXT
DAY OR TWO...RESULTING IN DRASTICALLY COOLER CONDITIONS...AND RAIN
...ACROSS A LARGE PORTION OF THE INLAND NORTHWEST. SLIGHTLY BELOW
NORMAL TEMPERATURES WILL PREVAIL THROUGH NEXT WEEK.
&&
.DISCUSSION...
TONIGHT THROUGH MONDAY...A HIGH VEIL OF CLOUDS HAS BEEN STREAMING
IN AND WILL LOWER AHEAD OF AN UPPER LEVEL SYSTEM ONLY NOW COMING ON
SHORE INTO NORTHERN CALIFORNIA. IN ADDITION TO THIS...SMOKE AND/OR
HAZE HAS BEEN A PERSISTENT FEATURE OF NOTE OVER THE CWA THROUGH
THE DAY...AND THIS WILL LIKELY CONTINUE UNTIL SOME MIXING OR
PRECIPITATION OCCURS...WHICH WILL BE SATURDAY OR SATURDAY NIGHT
FOR MOST LOCATIONS.
MODEL SOLUTIONS HAVE TRENDED STRONGLY IN LINE WITH THE ECMWF
THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK IN SLIGHTLY
WEAKENING/OPENING UP THE SYSTEM THAT IS COMING ON SHORE RIGHT NOW
AS IT TRAVERSES THE BASE OF THE MEAN LONGWAVE TROUGH THAT IS
GRADUALLY APPROACHING THE PACIFIC NORTHWEST. THE NET RESULT IS A
TRACK FOR THE SYSTEM THROUGH CENTRAL IDAHO AND INTO CENTRAL
MONTANA THROUGH SUNDAY NIGHT. THE GFS...CANADIAN...AND VIRTUALLY
ALL ENSEMBLE MEMBERS OF THE GFS SUPPORT THE ECMWF IN THIS
TRACK...SO THE CONSENSUS WAS HARD TO ARGUE WITH. THE NAM SOLUTION
WAS THE SLOW AND DEEP OUTLIER...TRACKING A MORE CLOSED MID-LEVEL
SYSTEM ACROSS SOUTHERN IDAHO THROUGH SUNDAY...MAKING IT ABOUT 5
DEGREES LATITUDE SOUTH AND 5 DEGREES LONGITUDE WEST OF THE MODEL
CONSENSUS. THE RESULT IS MUCH LESS NORTHWARD SPREAD OF
PRECIPITATION AND LIFT ACROSS THE AREA SATURDAY EVENING...AND MUCH
LESS QPF AT ANY POINT. HOWEVER...SINCE THE CONSENSUS LIFTED FAIRLY
GOOD LIFT THROUGH THE AREA...POPS FOR ESPECIALLY SATURDAY NIGHT
AND SUNDAY HAVE BEEN BOOSTED IN MANY LOCATIONS TO ACCOUNT FOR
STRONG Q-VECTOR CONVERGENCE AHEAD OF THE TROUGH THAT TRAVERSES THE
AREA WITH A GOOD LOW LEVEL MOISTURE SURGE AHEAD OF IT AS EVIDENT
BY A STRONG THETA-E RIDGE AT 850 MB AND 700 MB AS WELL AS MIXING
RATIOS IN THE LOW LEVELS APPROACHING 8 G/KG. FRONTAL LIFT IN A
RATHER DEEP LAYER FROM 850 MB UP TO 500 MB IS VERY IMPRESSIVE AND
ADDITIONAL HELP FROM THE DIVERGENT RIGHT ENTRANCE REGION OF A
STRONGLY CURVED UPPER JET STREAK TO OUR NORTH SHOULD HELP TO GIVE
FAIRLY GOOD COVERAGE TO THE RAIN SHIELD BY SATURDAY NIGHT ACROSS
MOST OF THE EASTERN HALF OF THE CWA.
IN THE WAKE OF SATURDAY NIGHT`S SYSTEM...ADDITIONAL SHORT WAVES
AND ASSOCIATED VORTICITY MAXIMA ARE SET TO ROUND THE BASE OF THE
MEAN LONG WAVE TROUGH...LIKELY AFFECTING MAINLY THE SOUTHEAST AND
EASTERN PORTIONS OF THE CWA...YIELDING UNSETTLED AND SHOWERY
CONDITIONS MAINLY ACROSS MOUNTAIN LOCATIONS. AND WITH TROUGHING
MOVING IN...SNOW LEVELS WILL LIKELY FALL IN MANY AREAS FROM 5500
FEET ACROSS THE CASCADES TO ABOUT 7500 FEET IN THE IDAHO PANHANDLE
BY MONDAY. BECAUSE OF THIS...HIGH TEMPERATURES WILL ALSO FALL
OFF...LIKELY BARELY HOLDING ONTO 60F IN SPOKANE BY THE LATTER HALF
OF THE WEEKEND. /FRIES
MONDAY NIGHT THROUGH FRIDAY...LONG-WAVE MODEL AGREEMENT IS GOOD
TO FAIR...BUT SHORT-WAVE MODEL AGREEMENT AND CONSISTENCY IS FAIR
TO POOR. THE LONG-WAVE TROUGH OVER THE WEST RETREATS INTO CANADA
BY TUESDAY NIGHT...AS A SHARPER SHORT-WAVE TROUGH ON ITS EAST SIDE
MIGRATES TOWARD THE GREAT LAKES. THIS LEAVES A ZONAL FLOW (OR
BROAD BUT LOW-GRADE TROUGH) OVER THE PACIFIC NW THROUGH WEDNESDAY
NIGHT. THIS IS FOLLOWED BY A SUGGESTION OF LOW-GRADE SHORT-WAVE
RIDGING TOWARD THE END OF THE PERIOD AHEAD OF AN APPROACHING
SHORT-WAVE TROUGH. HOWEVER THE SHORT-WAVE DISAGREEMENTS COME INTO
PLAY FROM THE START OF THE PERIOD AND DEGRADES OVERALL FORECAST
CONFIDENCE. THE 12Z GFS IS QUICKER TO TRANSITION TO THE ZONAL FLOW
THAN OTHER MODELS AND BRINGS THE WAVE (NOW TRACKING EAST OF THE
DATELINE) INTO THE AREA QUICKER AND SLIGHTLY DEEPER AND FURTHER
SOUTH THAN OTHER MODELS. THIS DIVERGES FROM SEVERAL OF THE
PREVIOUS RUNS OF THE GFS...AND IS QUICKER THAN THE GEFS. SO THE
FORECAST WILL LEAN AWAY FROM THE 12Z GFS ATTM. THE ECMWF IS
QUICKER TO THE DEVELOP THE END-OF-PERIOD-WAVE THAN THE OTHER
MODELS. A BLEND IS USED FOR THIS TIME FRAME.
LOOK FOR A CONTINUED RISK FOR SHOWERS OVER THE EASTERN MTN ZONES
AND NEAR THE CASCADES MONDAY NIGHT AND TUESDAY...WITH THE EXITING
SHORT-WAVE. THE NEXT FRONTAL WAVE APPROACHES THE REGION FOR
TUESDAY NIGHT INTO WEDNESDAY NIGHT. LEANING TOWARD THE ECMWF AND
PREVIOUS RUNS OF THE GFS...THIS WILL BRING AN INCREASE IN CLOUDS
TO THE CWA AND A RENEWED CHANCE FOR PRECIP AT THE CASCADES AND
NORTHERN CWA. SOME PRECIP RISK WILL ALSO SPILL OVER INTO THE IDAHO
PANHANDLE AND ERN WA. WEAK SHORT-WAVE RIDGING TOWARD THE END OF
THE PERIOD WILL NUDGE THE MOISTURE NORTH...BUT CONTINUE TO BRING
SOME RISK FOR PRECIP ACROSS THE CASCADES AND NEAR THE CANADIAN
BORDER.
TEMPERATURES ARE PROJECTED TO BE BELOW AVERAGE AT THE START OF
THIS PERIOD...MODERATING CLOSER TO AVERAGE BY THE END AS 850 TEMPS
PUSH TOWARD THE UPPER SINGLE DIGITS/LOWER TEENS AND 1000/500
THICKNESSES RECOVER FROM NEAR 550 DAM TO NEAR 560 DAM. /JCOTE
&&
.AVIATION...
A STORM SYSTEM MOVES FROM NORTH CA TO EAST OR/SW ID BY 00Z
SUNDAY...WITH MOISTURE DEEPENING FROM THE SSW. VFR CONDITIONS
EXPECTED AT ALL TAF SITES THROUGH 18Z SATURDAY...BUT LOOK FOR AN
INCREASE AND LOWERING OF MID AND HIGH CLOUDS. AFTER 18Z LCL MVFR
CIGS DEVELOP AFTER OVER SE WA/CENTRAL ID AS THE SYSTEM
APPROACHES...WITH RAIN BECOMING INCREASINGLY LIKELY. CIGS LOWER AND
RAIN CHANCES INCREASE OVER THE KGEG-KCOE CORRIDOR TOWARD SAT PM
(20Z-00Z). EXPECT MTN OBSCURATIONS AFTER 18-21Z SATURDAY. VFR
CONDITIONS EXPECTED TO PREVAIL OVER WRN TAF SITES (KMWH-KEAT)...WITH
ONLY A PASSING RISK FOR RAIN ATTM. /JCOTE
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 58 69 50 62 47 60 / 0 30 80 50 10 20
COEUR D`ALENE 54 70 49 60 46 59 / 0 30 80 70 20 30
PULLMAN 52 66 47 63 46 60 / 10 50 70 30 20 30
LEWISTON 61 70 55 67 52 66 / 10 60 60 10 20 20
COLVILLE 46 73 45 65 41 62 / 0 10 60 30 20 20
SANDPOINT 47 71 46 58 44 56 / 0 20 80 80 30 30
KELLOGG 54 69 49 56 45 55 / 0 50 80 80 50 50
MOSES LAKE 57 74 49 72 47 69 / 10 20 10 10 10 10
WENATCHEE 58 73 52 71 50 63 / 10 20 10 10 10 10
OMAK 51 76 48 73 46 65 / 0 10 20 10 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
000
FXUS66 KSEW 192235
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
330 PM PDT FRI SEP 19 2008
.SYNOPSIS...ONSHORE FLOW WILL CONTINUE OVER THE WEEKEND WITH A
CHANCE OF SHOWERS AS A SERIES OF UPPER LEVEL TROUGHS PASS THROUGH
THE REGION. AS A RESULT EXPECT THE CLOUDY CONDITIONS TO CONTINUE
WITH TEMPERATURES BELOW NORMAL. ANOTHER SYSTEM WILL AFFECT WESTERN
WASHINGTON EARLY NEXT WEEK WITH WIDE SPREAD RAIN POSSIBLE.
&&
.SHORT TERM...MARINE LAYER HELD TOGETHER PRETTY STRONG THIS
AFTERNOON AS MAJORITY OF THE LOWLANDS REMAINED SOCKED IN. LOW CLOUDS
OVER THE SW INTERIOR DID MIX OUT...BUT NOW SEEING INCREASING
MID/HIGH LEVEL CLOUDS MOVING IN FROM THE SOUTH. LOW CLOUDS KEPT THE
TEMPS DOWN AGAIN WITH HIGHS SO FAR ONLY IN THE UPPER 50S TO LOWER
60S...A GOOD 10 DEGREES BELOW NORMAL FOR THE INTERIOR.
UPPER LOW MOVING INTO ORE THIS AFTERNOON WILL TRACK FARTHER NORTH
THIS EVENING...ALTHOUGH BEST DYNAMICS AND FORCING WILL STAY SOUTH OF
OUR AREA. HAVE NOT SEEN ANY PRECIP REPORTS IN ORE YET...BUT ANY
SHOWERS THAT DO DEVELOP WILL LIKELY ONLY AFFECT THE CASCADES. THUS
WILL KEEP LOW 20 PERCENT POPS IN FOR TONIGHT. STRATUS WILL FILL BACK
IN OVERNIGHT AND DEEPEN AS UPPER LEVEL TROUGH AXIS PASSES THROUGH.
AS A RESULT...WILL SEE AREAS OF DRIZZLE ONCE AGAIN THROUGH THE
MORNING THEN A CHANCE OF SHOWERS IN THE AFTERNOON.
CLOUDY AND COOL CONDITIONS CONTINUE ON SUNDAY AS ANOTHER TROUGH
PASSES OVER THE REGION. HOWEVER...MAY SEE A LITTLE MORE RAIN WITH
THIS SYSTEM AS A WEAK COLD FRONT ALSO DRAGS THROUGH. GFS IS SHOWING
A DRIER SOLUTION FOR MONDAY BUT THE ECMWF STILL KEEPS A TROUGH OVER
THE REGION. FOR NOW WILL LEAVE LOW END POPS IN THE FORECAST AN
STRONG ONSHORE FLOW CONTINUES. 33
.LONG TERM...LOW CONFIDENCE IN THE FORECAST TUESDAY AND BEYOND AS
BOTH THE GFS AND ECMWF DISAGREE ON TIMING OF NEXT SYSTEM...WHICH IS
CURRENTLY LOCATED BACK ALONG 40N AND 165W. SO FAR THE GFS IS
FAVORING A FASTER SOLUTION WITH A 1000MB SFC LOW DEVELOPING OFFSHORE
AND STRONG WAA/WARM FRONTAL PRECIP CLIPPING THE AREA BY TUE. THE
ECMWF IS MUCH MUCH SLOWER WITH THIS SYSTEM...WHICH SHOWS IT STILL
OUTSIDE 130W BY 00Z WED. BOTH SOLUTIONS REMAIN OUT OF SYNC THROUGH
THE END OF THE WEEK SO WILL NOT MAKE ANY DRASTIC CHANGES TO THE
FORECAST YET. 33
&&
.AVIATION...THE AIR MASS ACROSS WESTERN WASHINGTON IS QUITE STABLE
WITH MARINE MOISTURE EXTENDING UP TO 3500 FT IN THE INTERIOR. WHILE
CLOUDS OVER THE SOUTH INTERIOR AND JUST OFF THE PACIFIC COASTLINE
HAVE ERODED TODAY...THEY CONTINUE TO BE QUITE EXTENSIVE IN THE
INTERIOR FROM KOLM NORTHWARD AND OUT THROUGH THE STRAIT OF JUAN DE
FUCA. IT DOES NOT APPEAR THAT DEVELOPING ONSHORE FLOW THROUGH THE
STRAIT THIS AFTERNOON WILL BE SUFFICIENT TO MIX UP THE BOUNDARY
LAYER TONIGHT.
A SPLITTING COLD FRONT FROM THE QUEEN CHARLOTTE ISLANDS SOUTHWARD
ALONG 132W...AND AN UPPER TROUGH EXTENDING NW FROM A CUTOFF
LOW OFF THE NORTHERN CALIFORNIA COAST...WILL MOVE SLOWLY EAST LATE
TONIGHT AND SATURDAY. THESE FEATURES SHOULD REMAIN FAR ENOUGH TO THE
WEST OVERNIGHT TO ALLOW CLOUDS TO THICKEN AGAIN IN THE INTERIOR. AT
THIS POINTS IT APPEARS THAT MOST AREAS IN THE INTERIOR WILL SEE
BASES NEAR 010 MSL AND TOPS AROUND 035. IFR CONDITIONS ARE EXPECTED
BETWEEN 12Z AND 19Z AT ELEVATED TERMINALS LIKE KSEA AND KPAE.
CONDITIONS MAY BE A LITTLE WORSE THAN INDICATED IF LIFT ASSOCIATED
WITH THE INCOMING UPPER TROUGH IS SUFFICIENT TO PRODUCE MORE THAN
PATCHY DRIZZLE. TEMPERATURES WILL COOL ENOUGH ALOFT TO LIFT
CONDITIONS AT MOST LOCATIONS TO P6SM BKN030 BKN-OVC050 20Z ONWARD.
KSEA...CONDITIONS WILL CONTINUE TO IMPROVE SOMEWHAT EARLY THIS
EVENING WITH SKIES POSSIBLY BREAKING OUT ABOUT 00Z. BUT STRATUS WILL
QUICKLY REDEVELOP THIS EVENING. CEILINGS WILL GRADUALLY FALL
OVERNIGHT WITH A LAYER FORMING 007-010 AROUND 12Z. AT THIS POINT
WILL LIMIT VIS RESTRICTIONS TO 4SM -DZ/BR 13Z-17Z...BUT THERE IS A
30 PERCENT CHANCE THAT CEILINGS AND VISIBILITIES WILL BE LOWER.
CONDITIONS WILL LIFT TO BKN025-030 BKN-OVC050 AROUND 20Z. ALBRECHT
&&
MARINE...ONSHORE PRESSURE GRADIENTS ARE SLOWLY DEVELOPING THIS
AFTERNOON AND WESTERLY WINDS THROUGH THE STRAIT OF JUAN DE FUCA ARE
AROUND 10 KT. WHILE CONFIDENCE IN SMALL CRAFT ADVISORY CONDITIONS IN
THE STRAIT IS LOW...WILL MAINTAIN A LOW END SMALL CRAFT ADVISORY
THERE TO MAINTAIN CONTINUITY...MAINTAIN CONSISTENCY WITH CANADIAN
FORECASTERS...AND SINCE THE MM5 INSISTS THAT THE PROCESS WILL
ACCELERATE EARLY THIS EVENING. FLOW WILL WEAKEN AGAIN TOWARD MORNING
AS MARINE CLOUDS REDEVELOP IN THE INTERIOR AND AS A STRETCHING
FRONTAL SYSTEM APPROACHES FROM THE WEST.
HIGH PRESSURE WILL BUILD IN THE OFFSHORE WATERS AND PRESSURE
GRADIENTS WILL INCREASE AGAIN LATER SATURDAY AS AN UPPER LEVEL
DISTURBANCE MOVES ACROSS THE AREA. BUT AT THIS TIME IT DOES NOT
APPEAR THAT SMALL CRAFT ADVISORY CONDITIONS WILL DEVELOP IN THE
STRAIT.
A SERIES OF WEAK DISTURBANCES WILL MAINTAIN LIGHT TO MODERATE
ONSHORE FLOW SUNDAY INTO MONDAY NIGHT. HIGH PRES WILL SETTLE INTO
THE AREA TUE. A WARM FRONT ASSOCIATED WITH A WEAKENING LOW WILL
MOVE THROUGH THE WATERS LATE TUE NIGHT OR WED. ALBRECHT
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.
&&
$$
WEATHER.GOV/SEATTLE
000
FXUS66 KPQR 192150
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
300 PM PDT FRI SEP 19 2008
.SYNOPSIS...AN UPPER LEVEL LOW PRESSURE AREA OFF THE NORTHERN
CALIFORNIA COAST WILL WEAKEN TO AN UPPER LEVEL TROUGH AND
MOVE INTO NORTHERN CALIF AND SOUTHERN OREGON TONIGHT. INFRARED
SATELLITE IMAGERY SHOWS CLOUDS ROTATING NORTH FROM THAT WEATHER
SYSTEM AND NATIONAL WEATHER SERVICE DOPPLER THOSE COULD PRODUCE SOME
LIGHT PRECIPITATION OVER THE CASCADES AND FOOTHILLS AND EAST PART OF
THE COLUMBIA GORGE THIS EVENING AND SATURDAY. ANOTHER WEAK LOW
PRESSURE SYSTEM FROM THE GULF OF ALASKA WILL BRUSH BY THE NORTH
PART OF THE FORECAST AREA SATURDAY AND COULD PRODUCE SOME LIGHT
PRECIPITATION NEAR THE NORTH COAST SATURDAY. THAT SYSTEM WILL KEEP
DIGGING SOUTH INTO THE FORECAST AREA BRINGING A FEW SHOWERS TO THE
AREA THIS WEEKEND AND EARLY NEXT WEEK WITH THE BEST PROSPECTS OF
MEASURABLE PRECIPITATION LATE SUNDAY INTO MONDAY IN THE NORTH PART OF
THE FORECAST AREA.
&&
.SHORT TERM...INFRARED SATELLITE IMAGERY SHOWS AN UPPER LEVEL LOW
PRESSURE AREA CENTERED NEAR 40N 125.5W OFF THE NORTHERN CALIFORNIA
COAST MOVING EAST AND ROTATING CLOUDS NORTH OVER THE FORECAST AREA
EARLY THIS AFTERNOON AND NATIONAL WEATHER SERVICE RADAR DOPPLER RADAR
SHOWS SHOWERS FROM THE LOW ROTATING ACROSS EASTERN OREGON AND INTO
THE CASCADES. MOST OF THE MARINE STATUS IN THE WILLAMETTE VALLEY
HAS BROKEN APART AND LIFTED OUT AND WHAT IS LEFT WILL CONTINUE TO
THIN RAPIDLY AND LIFT OUT OVER THE NEXT SEVERAL HOURS TO BE REPLACED
BY MIDDLE AND HIGH CLOUDS FROM THE APPROACHING UPPER LEVEL LOW. THE
LOW ALOFT WILL WEAKEN TO A NEGATIVE TILT DIFFLUENT UPPER LEVEL TROUGH
AS IT COMES INLAND TONIGHT WITH SOME SHOWERS CONTINUING OVER THE EAST
SIDE OF THE FORECAST AREA. A WEAK UPPER LEVEL SHORTWAVE WILL MOVE
ACROSS THE FORECAST AREA SATURDAY WITH LOW CHANCES FOR SHOWERS OVER
THE NORTHERN COAST ZONES. A LEFT JET SEGMENT EXIT REGION WILL MOVE
INTO THE FORECAST AREA ADDING DYNAMICS TO A MORE ENERGETIC UPPER
LEVEL TROUGH DIGGING INTO THE FORECAST AREA SUNDAY INTO MONDAY WITH
BETTER POSSIBILITY OF SHOWERS...EXPECT THE BEST PROSPECTS OF
MEASURABLE RAIN ON THE NORTH COAST/COAST RANGE AND WILLAPA HILLS WITH
THAT WEATHER SYSTEM. WILLSON
.LONG TERM...LONG RANGE MODELS CONTINUE TO SHOW A LOT OF VARIABILITY
IN THE EXTENDED TIME PERIOD. THE 12Z RUN OF THE GFS INTRODUCES A
CUT-OFF LOW SLIDING THROUGH OUR AREA TUESDAY INTO WEDNESDAY...WHICH
IS OUT OF PHASE WITH PREVIOUS RUNS AND CURRENT THINKING. HAVE KEPT
FORECAST MORE IN LINE WITH PREVIOUS RUNS OF GFS AND ECMWF FOR TIME
BEING UNTIL ALL MID RANGE MODELS BEGIN TO SHOW SOME AGREEMENT.
SHOULD SEE MODERATE TEMPERATURES AND CLOUDY SKIES THROUGH MUCH OF
THE LATTER HALF OF NEXT WEEK. BROWN
&&
.AVIATION...AT 2130Z ONE PATCH OF STRATUS CLOUDS LEFT IN THE CENTRAL
WILLAMETTE FVALLEY. VFR CONDITIONS WILL CONTINUE THIS AFTERNOON AND
EVENING. NOT MUCH LOW CLOUDS OFFSHORE BUT EXPECT THEM TO REFORM LATE
TONIGHT WITH AREAS OF IFR CIGS AND VISIBILITY ALONG THE COAST AFTER
08Z. SOME LOW CLOUDS MAY RE FORM OVER THE INLAND VALLEYS TOMORROW
FOR AREAS OF MVFR DURING THE MORNING IN THE ONSHORE FLOW. WS
KPDX AND APPROACHES...VFR CONDITIONS WITH HIGH CLOUDS THROUGH
TONIGHT. POSSIBLE MVFR CIGS 13Z TO 20Z TOMORROW.
&&
.MARINE...WEAK HIGH PRESSURE OVER THE COASTAL WATERS WILL CAUSE
LIGHT WINDS/SEAS TO CONTINUE INTO SAT. SWELL AT AOUND 5 FEET.
OTHERWISE SEAS SHOULD BE LESS THAN 5 FT. THE LIGHT SWELL IS ALLOWING
THE COLUMBIA RIVER BAR TO REMAIN FREE OF ADVISORIES DESPITE THE
STRONG ASTRONOMICAL EVENING EBB CURRENTS THIS WEEK. INCREASING NW
WINDS/SEAS LIKELY LATER SUN NIGHT AND MON AS HIGH PRES BUILDS IN
BEHIND A WEAK GULF OF ALASKA COLD FRONT. WS
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR/WA...NONE.
&&
.PRELIMINARY POINT POPS (PROBABILITY OF MEASURABLE PRECIPITATION)
AST 122222 PDX 111221 SLE 111221 EUG 111221
2
$$
MORE WEATHER INFORMATION ONLINE AT...
http://weather.gov/portland
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KOTX 192124
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
224 PM PDT FRI SEP 19 2008
.SYNOPSIS...
A DEEP UPPER LEVEL SYSTEM WILL MOVE BY TO OUR SOUTHEAST OVER THE
NEXT DAY OR TWO...RESULTING IN DRASTICALLY COOLER CONDITIONS AND
RAIN ACROSS A LARGE PORTION OF THE INLAND NORTHWEST. SLIGHTLY
BELOW NORMAL TEMPERATURES WILL PREVAIL THROUGH NEXT WEEK.
&&
.DISCUSSION...
TONIGHT THROUGH MONDAY...A HIGH VEIL OF CLOUDS HAS BEEN STREAMING
IN AND WILL LOWER AHEAD OF AN UPPER LEVEL SYSTEM ONLY NOW COMING ON
SHORE INTO NORTHERN CALIFORNIA. IN ADDITION TO THIS...SMOKE AND/OR
HAZE HAS BEEN A PERSISTENT FEATURE OF NOTE OVER THE CWA THROUGH
THE DAY...AND THIS WILL LIKELY CONTINUE UNTIL SOME MIXING OR
PRECIPITATION OCCURS...WHICH WILL BE SATURDAY OR SATURDAY NIGHT
FOR MOST LOCATIONS.
MODEL SOLUTIONS HAVE TRENDED STRONGLY IN LINE WITH THE ECMWF
THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK IN SLIGHTLY
WEAKENING/OPENING UP THE SYSTEM THAT IS COMING ON SHORE RIGHT NOW
AS IT TRAVERSES THE BASE OF THE MEAN LONGWAVE TROUGH THAT IS
GRADUALLY APPROACHING THE PACIFIC NORTHWEST. THE NET RESULT IS A
TRACK FOR THE SYSTEM THROUGH CENTRAL IDAHO AND INTO CENTRAL
MONTANA THROUGH SUNDAY NIGHT. THE GFS...CANADIAN...AND VIRTUALLY
ALL ENSEMBLE MEMBERS OF THE GFS SUPPORT THE ECMWF IN THIS
TRACK...SO THE CONSENSUS WAS HARD TO ARGUE WITH. THE NAM SOLUTION
WAS THE SLOW AND DEEP OUTLIER...TRACKING A MORE CLOSED MID-LEVEL
SYSTEM ACROSS SOUTHERN IDAHO THROUGH SUNDAY...MAKING IT ABOUT 5
DEGREES LATITUDE SOUTH AND 5 DEGREES LONGITUDE WEST OF THE MODEL
CONSENSUS. THE RESULT IS MUCH LESS NORTHWARD SPREAD OF
PRECIPITATION AND LIFT ACROSS THE AREA SATURDAY EVENING...AND MUCH
LESS QPF AT ANY POINT. HOWEVER...SINCE THE CONSENSUS LIFTED FAIRLY
GOOD LIFT THROUGH THE AREA...POPS FOR ESPECIALLY SATURDAY NIGHT
AND SUNDAY HAVE BEEN BOOSTED IN MANY LOCATIONS TO ACCOUNT FOR
STRONG Q-VECTOR CONVERGENCE AHEAD OF THE TROUGH THAT TRAVERSES THE
AREA WITH A GOOD LOW LEVEL MOISTURE SURGE AHEAD OF IT AS EVIDENT
BY A STRONG THETA-E RIDGE AT 850 MB AND 700 MB AS WELL AS MIXING
RATIOS IN THE LOW LEVELS APPROACHING 8 G/KG. FRONTAL LIFT IN A
RATHER DEEP LAYER FROM 850 MB UP TO 500 MB IS VERY IMPRESSIVE AND
ADDITIONAL HELP FROM THE DIVERGENT RIGHT ENTRANCE REGION OF A
STRONGLY CURVED UPPER JET STREAK TO OUR NORTH SHOULD HELP TO GIVE
FAIRLY GOOD COVERAGE TO THE RAIN SHIELD BY SATURDAY NIGHT ACROSS
MOST OF THE EASTERN HALF OF THE CWA.
IN THE WAKE OF SATURDAY NIGHT`S SYSTEM...ADDITIONAL SHORT WAVES
AND ASSOCIATED VORTICITY MAXIMA ARE SET TO ROUND THE BASE OF THE
MEAN LONG WAVE TROUGH...LIKELY AFFECTING MAINLY THE SOUTHEAST AND
EASTERN PORTIONS OF THE CWA...YIELDING UNSETTLED AND SHOWERY
CONDITIONS MAINLY ACROSS MOUNTAIN LOCATIONS. AND WITH TROUGHING
MOVING IN...SNOW LEVELS WILL LIKELY FALL IN MANY AREAS FROM 5500
FEET ACROSS THE CASCADES TO ABOUT 7500 FEET IN THE IDAHO PANHANDLE
BY MONDAY. BECAUSE OF THIS...HIGH TEMPERATURES WILL ALSO FALL
OFF...LIKELY BARELY HOLDING ONTO 60F IN SPOKANE BY THE LATTER HALF
OF THE WEEKEND. /FRIES
MONDAY NIGHT THROUGH FRIDAY...LONG-WAVE MODEL AGREEMENT IS GOOD
TO FAIR...BUT SHORT-WAVE MODEL AGREEMENT AND CONSISTENCY IS FAIR
TO POOR. THE LONG-WAVE TROUGH OVER THE WEST RETREATS INTO CANADA
BY TUESDAY NIGHT...AS A SHARPER SHORT-WAVE TROUGH ON ITS EAST SIDE
MIGRATES TOWARD THE GREAT LAKES. THIS LEAVES A ZONAL FLOW (OR
BROAD BUT LOW-GRADE TROUGH) OVER THE PACIFIC NW THROUGH WEDNESDAY
NIGHT. THIS IS FOLLOWED BY A SUGGESTION OF LOW-GRADE SHORT-WAVE
RIDGING TOWARD THE END OF THE PERIOD AHEAD OF AN APPROACHING
SHORT-WAVE TROUGH. HOWEVER THE SHORT-WAVE DISAGREEMENTS COME INTO
PLAY FROM THE START OF THE PERIOD AND DEGRADES OVERALL FORECAST
CONFIDENCE. THE 12Z GFS IS QUICKER TO TRANSITION TO THE ZONAL FLOW
THAN OTHER MODELS AND BRINGS THE WAVE (NOW TRACKING EAST OF THE
DATELINE) INTO THE AREA QUICKER AND SLIGHTLY DEEPER AND FURTHER
SOUTH THAN OTHER MODELS. THIS DIVERGES FROM SEVERAL OF THE
PREVIOUS RUNS OF THE GFS...AND IS QUICKER THAN THE GEFS. SO THE
FORECAST WILL LEAN AWAY FROM THE 12Z GFS ATTM. THE ECMWF IS
QUICKER TO THE DEVELOP THE END-OF-PERIOD-WAVE THAN THE OTHER
MODELS. A BLEND IS USED FOR THIS TIME FRAME.
LOOK FOR A CONTINUED RISK FOR SHOWERS OVER THE EASTERN MTN ZONES
AND NEAR THE CASCADES MONDAY NIGHT AND TUESDAY...WITH THE EXITING
SHORT-WAVE. THE NEXT FRONTAL WAVE APPROACHES THE REGION FOR
TUESDAY NIGHT INTO WEDNESDAY NIGHT. LEANING TOWARD THE ECMWF AND
PREVIOUS RUNS OF THE GFS...THIS WILL BRING AN INCREASE IN CLOUDS
TO THE CWA AND A RENEWED CHANCE FOR PRECIP AT THE CASCADES AND
NORTHERN CWA. SOME PRECIP RISK WILL ALSO SPILL OVER INTO THE IDAHO
PANHANDLE AND ERN WA. WEAK SHORT-WAVE RIDGING TOWARD THE END OF
THE PERIOD WILL NUDGE THE MOISTURE NORTH...BUT CONTINUE TO BRING
SOME RISK FOR PRECIP ACROSS THE CASCADES AND NEAR THE CANADIAN
BORDER.
TEMPERATURES ARE PROJECTED TO BE BELOW AVERAGE AT THE START OF
THIS PERIOD...MODERATING CLOSER TO AVERAGE BY THE END AS 850 TEMPS
PUSH TOWARD THE UPPER SINGLE DIGITS/LOWER TEENS AND 1000/500
THICKNESSES RECOVER FROM NEAR 550 DAM TO NEAR 560 DAM. /JCOTE
&&
.AVIATION...
SOME AREAS OF HAZE ARE EVIDENT AROUND THE AREA THIS MORNING...WHICH
HAVE OCCASIONALLY SHOWN ON OBS FROM KDEW AND KPUW.
OTHERWISE...SCATTERED TO BROKEN MID-LEVEL CLOUD DECKS WILL PREVAIL
THROUGH THE DAY WITH THE POSSIBILITY OF SOME VIRGA THIS
AFTERNOON...THOUGH NSW SEEMS TO BE THE MOST LIKELY SCENARIO AT ALL
TAF SITES WITH VFR CONDITIONS THROUGH 18Z SATURDAY. /FRIES
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 58 69 50 62 47 60 / 0 30 80 50 10 20
COEUR D`ALENE 54 70 49 60 46 59 / 0 30 80 70 20 30
PULLMAN 52 66 47 63 46 60 / 10 50 70 30 20 30
LEWISTON 61 70 55 67 52 66 / 10 60 60 10 20 20
COLVILLE 46 73 45 65 41 62 / 0 10 60 30 20 20
SANDPOINT 47 71 46 58 44 56 / 0 20 80 80 30 30
KELLOGG 54 69 49 56 45 55 / 0 50 80 80 50 50
MOSES LAKE 57 74 49 72 47 69 / 10 20 10 10 10 10
WENATCHEE 58 73 52 71 50 63 / 10 20 10 10 10 10
OMAK 51 76 48 73 46 65 / 0 10 20 10 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
000
FXUS66 KOTX 191801
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1100 AM PDT FRI SEP 19 2008
.SYNOPSIS...
A STRONG RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE INLAND
NORTHWEST RESULTING IN ANOTHER DAY OF UNSEASONABLY WARM WEATHER
FRIDAY. THE RIDGE WILL BEGIN TO SLOWLY BREAK DOWN THROUGH THE
WEEKEND AS AN OFFSHORE TROUGH MOVES INLAND. THIS TROUGH WILL BRING
A GRADUAL COOLING TREND AS WELL AS INCREASING CHANCES OF
PRECIPITATION.
&&
.DISCUSSION...
UPDATE...VISIBLE IMAGERY HAS BEGUN TO ROLL IN NOW...AND A LARGE
AMOUNT OF ALTOCUMULUS CASTELLATUS HAS BEEN REVEALED THAT WASN`T
READILY DISCERNIBLE ON THE IR IMAGERY OVERNIGHT. LAPSE RATES ARE
FAIRLY STEEP FROM THE TOP OF THE MORNING INVERSION UP TO 575 MB OR
SO AND AGAIN ABOVE 450 MB...HOWEVER IT SEEMS MOST OF THE ACCUS IS
LIKELY AT THE TOP OF THE LOWER INSTABILITY LEVEL...WHERE THE ONLY
AREA EVEN NEARLY SATURATED ON THE 12Z KOTX SOUNDING
EXISTS...AROUND 600 MB. BELOW THIS LEVEL...DEWPOINT DEPRESSIONS
TOP OUT NEAR 27C...SO A VERY DRY LOWER 400 MB EXISTS TO SAY THE
LEAST. THE RATHER IMPRESSIVE MID-LEVEL LAPSE RATES AND EARLY
MORNING CLOUD SIGNATURES WILL LIKELY ALLOW FOR SOME VIRGA THIS
AFTERNOON AS THE BUILDUPS FLARE A BIT...HOWEVER THE DRY LOWER
ATMOSPHERE WILL ERADICATE ANY PRECIPITATION THAT COMES OUT OF THE
CLOUDS BEFORE IT TOUCHES THE GROUND. ADDITIONALLY...UPPER LEVEL
LIFT IN ASSOCIATION WITH THE LOW COMING INTO THE NORTHERN
CALIFORNIA COAST REMAINS TO OUR SOUTH AND WEST THROUGH THE
DAY...SO WITH A LACK OF ANY SYNOPTIC FORCING...WHATEVER ACTIVITY
THAT MAY INITIATE FROM THE MID-LEVELS WILL LIKELY BE RATHER SHORT
LIVED.
TEMPERATURES FOR TODAY LOOK SIMILAR TO YESTERDAY...WITH THE
EASTERN CWA LIKELY THE WARMEST PART OF THE ENTIRE AREA. ACROSS THE
CASCADES...TIGHT TEMPERATURE GRADIENTS AT 925 AND 850 MB SUGGEST A
DECENT MARINE PUSH TOWARD THE CASCADES...SO TEMPERATURES ALONG THE
CREST ARE LIKELY TO BE THE ONLY ONES IN THE CWA COOLER THAN
YESTERDAY. OTHERWISE...HIGHS APPROACHING RECORD VALUES STILL SEEM
POSSIBLE ACROSS THE NORTHERN ZONES...WITH MUCH OF THE CWA A DOZEN
DEGREES ABOVE NORMAL. /FRIES
&&
.AVIATION...
SOME AREAS OF HAZE ARE EVIDENT AROUND THE AREA THIS MORNING...WHICH
HAVE OCCASIONALLY SHOWN ON OBS FROM KDEW AND KPUW.
OTHERWISE...SCATTERED TO BROKEN MID-LEVEL CLOUD DECKS WILL PREVAIL
THROUGH THE DAY WITH THE POSSIBILITY OF SOME VIRGA THIS
AFTERNOON...THOUGH NSW SEEMS TO BE THE MOST LIKELY SCENARIO AT ALL
TAF SITES WITH VFR CONDITIONS THROUGH 18Z SATURDAY. /FRIES
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 87 55 72 50 68 47 / 0 0 30 40 20 20
COEUR D`ALENE 89 53 72 50 66 46 / 0 0 30 50 40 30
PULLMAN 87 51 72 48 68 45 / 0 10 30 30 20 30
LEWISTON 93 62 78 56 74 53 / 0 20 30 30 10 20
COLVILLE 90 48 76 45 69 41 / 0 0 30 50 40 30
SANDPOINT 79 48 71 47 64 44 / 0 0 30 50 50 30
KELLOGG 88 50 70 50 61 46 / 0 10 40 50 50 40
MOSES LAKE 86 56 78 50 75 47 / 0 10 20 10 10 20
WENATCHEE 86 59 76 52 74 51 / 0 10 20 10 10 20
OMAK 88 55 76 48 75 46 / 0 0 20 10 10 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
000
FXUS66 KSEW 191636
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
930 AM PDT FRI SEP 19 2008
.SYNOPSIS...ONSHORE FLOW WILL KEEP CLOUDY AND COOL CONDITIONS OVER
THE AREA TODAY. A WEAK WEATHER SYSTEM WILL MOVE THROUGH THE REGION
THIS WEEKEND. A SHARPER COOLER UPPER LEVEL TROUGH WILL ARRIVE SUNDAY
NIGHT. AN UNSETTLED WEATHER PATTERN IS LIKELY NEXT WEEK.
&&
.SHORT TERM...STRATUS LAYER IS A LITTLE THICKER ACROSS W WA THIS
MORNING ALTHOUGH LATEST VISIBLE SATELLITE IMAGE DOES SHOW SOME
BREAKS ALONG THE COAST. THE INTERIOR LOOKS SOCKED IN ONCE AGAIN WITH
NOT A LOT OF HOPE FOR SUNSHINE THIS AFTERNOON...ESPECIALLY SINCE WE
WILL SEE INCREASING MID/HIGH LEVEL CLOUDS STREAMING IN. ANY BREAKS
WILL BE BRIEF SO WILL STICK WITH A MOSTLY CLOUDY FORECAST ACROSS THE
BOARD. TEMPERATURES WILL REMAIN ON THE COOL SIDE WITH HIGHS ONLY IN
THE LOW/MID 60S. MEANWHILE...UPPER TROUGH WILL MOVE INTO N CA THIS
MORNING WITH BEST DYNAMICS STAYING SOUTH OF THE CWA. MODELS TRY TO
SHOW SOME SHOWERS IN THE CASCADES THIS AFTERNOON AND EVENING...BUT
PRECIP AMOUNTS WILL REMAIN LIGHT.
UPPER TROUGH WILL MOVE INTO E ORE ON SAT...BUT COULD STILL SEE AREAS
OF LIGHT DRIZZLE IN OUR AREA THROUGH THE MORNING...WITH CLOUDY AND
COOL CONDITIONS CONTINUING. ANOTHER TROUGH WILL AFFECT THE AREA ON
SUN...WITH HIGHER CHANCES FOR PRECIP AS WEAK COLD FRONT PASSES
THROUGH. 33
.LONG TERM...PREVIOUS DISCUSSION...THE LATEST GFS HAS HEIGHTS RISING
100M MON NITE AND TUE WITH NO PRECIP...BUT DECENT ZONAL FLOW. A
SYSTEM SPLIT UP BETWEEN THE SRN AND NRN STREAMS SHOWS UP TUE NITE
BUT IS MUCH DRIER THAN YDYS SOLUTION BUT I THINK WILL PROBABLY TREND
BACK TO LOOKING WET. THE STRENGTH OF THE JET SUGGESTS WE ARE HEADING
BACK INTO AN ACTIVE WEATHER PATTERN. THE WRF EXTENSION SHOWS A LOT
OF SHOWER ACTIVITY AND A PSCZ ON MONDAY IN THE FAIRLY STRONG ONSHORE
FLOW BEHIND THE TROF...THE 84HR WRF VALID 12Z MON LOOKS GOOD FOR
SHOWERS AND PSCZ. THEN TUE IS MOSTLY DRY EXCEPT FOR MAYBE SCT
SHOWERS IN THE MOUNTAINS. THE UW`S WRF EXTENSION HAS SGFNT RAIN OVER
SW WA WED AS A 1016MB LOW REACHES THE SOUTH COAST...THAT IS PROBABLY
THE REMNANTS OF OLD TROPICAL MOISTURE WHICH HAS CROSSED THE PAC...IT
IS THE SRN STREAM SYSTEM IN THE GFS...BUT THE MODELS DO NOT SHOW IT
DEEPENING AS IT COMES IN. STILL...FOR NOW THE BEST CHANCE FOR PRECIP
LOOKS TO BE MON WITH SHOWERS AND AND WED FOR A RAIN EVENT. FCST
HASN`T YET BEEN PUSHED THAT DIRECTION. 19
&&
.AVIATION...A WEAK UPPER LEVEL TROUGH OF LOW PRESSURE ALOFT...
EXTENDING NORTHWEST FROM A CUT OFF LOW OFF THE NORTHERN CALIFORNIA
COAST...IS MOVING EAST INTO THE AREA SLOWER THAN PREVIOUSLY
EXPECTED. THIS SLOWER MOVEMENT WILL RESULT IN THE PERSISTENCE OF A
HIGHLY STABLE AND MOIST BOUNDARY LAYER IN THE INTERIOR.
AN EXTENSIVE AREA OF LOW LEVEL MOISTURE OVER THE INTERIOR TODAY WILL
BE SLOW TO LIFT. WHILE LOWER LAYERS BELOW 010 WILL LIFT ABOUT 18Z
WITH HIGHLY FILTERED MID SEP INSOLATION...LOCAL TOOLS BASED ON CLOUD
REPORTS FROM PIREPS AT KSEA AND KBFI SHOW THAT WE WILL HAVE A TOUGH
TIME BREAKING OUT TODAY. CONDITIONS HAVE BROKEN SOMEWHAT ALONG THE
COAST. SO DIFFERENTIAL BOUNDARY LAYER HEATING BETWEEN THE INTERIOR
AND COASTAL AREAS THIS AFTERNOON WILL LIKELY DIMINISH THE
PROBABILITY OF ONSHORE FLOW THIS AFTERNOON. THIS WOULD RESULT IN THE
REDEVELOPMENT OVERNIGHT OF WIDESPREAD IFR CONDITIONS IN THE INTERIOR
THAT WOULD PERSIST THROUGH SAT MORNING.
KSEA...CEILINGS WILL SLOWLY LIFT WITH ABOVE IFR AROUND 18Z AND TO
025 AROUND 22Z. VIS LIMITATIONS IN -DZ BR WILL IMPROVE ABOUT 18Z.
SURFACE WIND MAINLY LIGHT NWLY. GRADUALLY LOWERING CONDITIONS TO
P6SM BKN-OVC020 07Z AND TO 3-5SM -DZ BR BKN005 OVC009 13Z-18Z SAT AS
MOISTURE FILLS IN OVERNIGHT WITH STABLE CONDITIONS AND VERY LIGHT
FLOW. ALBRECHT
&&
MARINE...ONSHORE PRESSURE GRADIENTS WILL BE SLOWER TO DEVELOP THAN
PREVIOUSLY ANTICIPATED. WITH LOW CONFIDENCE...WILL MAINTAIN THE LOW
END SMALL CRAFT ADVISORY FOR THE CENTRAL AND EAST STRAIT FOR LATE
THIS AFTERNOON AND EVENING...BUT WILL CONSIDER DROPPING IT LATER
THIS AFTERNOON IF PRESSURE GRADIENTS DO NOT START INCREASING.
HIGH PRESSURE WILL BUILD IN THE OFFSHORE WATERS AND PRESSURE
GRADIENTS WILL INCREASE LATER SATURDAY AS AN UPPER LEVEL DISTURBANCE
MOVES ACROSS THE AREA. A SERIES OF WEAK DISTURBANCES WILL MAINTAIN
THE ONSHORE FLOW SUNDAY INTO MONDAY. A WEAKENING FRONT AND POSSIBLE
WEAK SURFACE LOW CENTER IS EXPECTED TO APPROACH THE COAST TUE.
ALBRECHT
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.
&&
$$
WEATHER.GOV/SEATTLE
000
FXUS66 KPQR 191604
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
900 AM PDT FRI SEP 19 2008
.SYNOPSIS...UPPER AIR SOUNDINGS SHOW A THINNER LAYER OF MARINE
STRATUS OVER THE FORECAST AREA THIS MORNING THAT WILL LIFT OUT AND
BREAK APART BY AFTERNOON. AN UPPER LEVEL LOW PRESSURE AREA OFF
THE NORTHERN CALIFORNIA IS WILL WEAKEN TO AN UPPER LEVEL TROUGH AND
MOVE INTO NORTHERN CALIF AND SOUTHERN OREGON TONIGHT. INFRARED
SATELLITE IMAGERY SHOWS CLOUDS ROTATING NORTH FROM THAT WEATHER
SYSTEM AND THOSE COULD PRODUCE SOME LIGHT PRECIPITATION OVER THE
CASCADES AND FOOTHILLS THIS AFTERNOON AND SATURDAY. ANOTHER WEAK LOW
PRESSURE SYSTEM FROM THE GULF OF ALASKA WILL BRUSH BY THE NORTH
PART OF THE FORECAST AREA SATURDAY AND COULD PRODUCE SOME LIGHT
PRECIPITATION NEAR THE NORTH COAST SATURDAY. THAT SYSTEM WILL KEEP
DIGGING SOUTH INTO THE FORECAST AREA BRINGING A FEW SHOWERS TO THE
AREA THIS WEEKEND AND EARLY NEXT WEEK WITH THE BEST PROSPECTS OF
MEASURABLE PRECIPITATION LATE SUNDAY INTO MONDAY IN THE NORTH PART OF
THE FORECAST AREA.
&&
.SHORT TERM...INFRARED SATELLITE IMAGERY AN UPPER LOW NEAR 40N 127.5W
OFF THE NORTHERN CALIFORNIA COAST ROTATING MID AND HIGHER CLOUDS OVER
THE FORECAST AREA EARLY THIS MORNING. MARINE STRATUS OVER THE
FORECAST AREA IS THINNER THIS MORNING AND WILL BREAK APART AND LIFT
OUT EARLY AFTERNOON. THE INCREASE IN LAPSE RATES AS AN UPPER LOW
APPROACHES NORTHERN CALIFORNIA/SOUTHERN OREGON AND THE UPPER LEVEL
RIDGE AXIS SHIFTS FARTHER TO THE EAST WILL ALSO CONTRIBUTE TO
BREAKING UP THE STRATUS. THE UPPER LEVEL LOW WILL WEAKEN TO A
NEGATIVE TILT DIFFLUENT UPPER LEVEL TROUGH AS IT COMES INLAND AND
COULD SEE SOME SHOWERS OVER THE CASCADES AS THE MID LEVEL MOISTURE
AND SOME INSTABILITY DEVELOPS THERE THIS AFTERNOON. A WEAK UPPER
LEVEL SHORTWAVE WILL MOVE ACROSS THE FORECAST AREA SATURDAY WITH LOW
CHANCES FOR SHOWERS OVER THE NORTHERN COAST ZONES. A LEFT JET
SEGMENT EXIT REGION WILL MOVE INTO THE FORECAST AREA ADDING DYNAMICS
TO A MORE ENERGETIC UPPER LEVEL TROUGH DIGGING INTO THE FORECAST AREA
SUNDAY INTO MONDAY WITH BETTER POSSIBILITY OF SHOWERS...EXPECT THE
BEST PROSPECTS OF MEASURABLE RAIN ON THE NORTH COAST/COAST RANGE AND
WILLAPA HILLS WITH THAT WEATHER SYSTEM. WILLSON
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
LONG RANGE MODELS CONTINUE TO SHOW A LOT OF VARIABILITY IN THE
EXTENDED TIME PERIOD. SHOWERS TAPER OFF MONDAY AS THE UPPER LEVEL
TROUGH MOVES OFF TO THE EAST OF THE FORECAST AREA...WITH A FEW
SHOWERS LINGERING OVER THE CASCADES. CONFIDENCE IS LOW FOR THE
REMAINDER OF THE FORECAST AS MODELS TREND TOWARD 180 DEGREES OUT OF
PHASE AT TIMES. WILLSON
&&
.AVIATION...MVFR CIGS ACROSS THE INLAND VALLEYS THIS MORNING. MARINE
INVERSION IS SHALLOWER TODAY AND THE STRATUS DECK OVER THE INLAND
VALLEYS IS ONLY AROUND 1000 FEET THICK. EXPECT THESE CLOUDS SCATTER
OUT IN MOST AREAS AROUND 19Z. SOME PATCHY FOG ALONG THE COAST THIS
MORNING AND A FEW AREAS OF STRATUS ARE BEING BROKEN UP BY THE UPPER
LOW LIFTING NORTHEAST ACROSS THE AREA TODAY. ONSHORE FLOW WILL
REMAIN IN PLACE TONIGHT SO EXPECT MVFR STRATUS TO RETURN TO THE
VALLEYS LATER TONIGHT. WS
KPDX AND APPROACHES...MVFR CIGS EXPECTED TO REMAIN IN PLACE THROUGH
THIS MORNING...WITH IMPROVEMENT TO VFR BY AFTERNOON.
&&
.MARINE...WEAK HIGH PRESSURE OVER THE COASTAL WATERS WILL CAUSE
LIGHT WINDS/SEAS TO CONTINUE INTO SAT. SOME 4-5 FT W-SW SWELL MAY
SNEAK INTO SOUTHERN WATERS TODAY FROM THE LOW PRES SYSTEM
APPROACHING THE NORTHERN CALIFORNIA COAST. OTHERWISE SEAS SHOULD BE
LESS THAN 5 FT. THE LIGHT SWELL IS ALLOWING THE COLUMBIA RIVER BAR
TO REMAIN FREE OF ADVISORIES DESPITE THE STRONG ASTRONOMICAL EVENING
EBB CURRENTS THIS WEEK. INCREASING NW WINDS/SEAS LIKELY LATER SUN
AND MON AS HIGH PRES BUILDS IN BEHIND A WEAK GULF OF ALASKA COLD
FRONT. RW
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR/WA...NONE.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR/WA...NONE.
&&
.PRELIMINARY POINT POPS (PROBABILITY OF MEASURABLE PRECIPITATION)
AST 11222 PDX 11112 SLE 11112 EUG 11112
$$
MORE WEATHER INFORMATION ONLINE AT...
http://weather.gov/portland
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KOTX 191547
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
847 AM PDT FRI SEP 19 2008
.SYNOPSIS...
A STRONG RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE INLAND
NORTHWEST RESULTING IN ANOTHER DAY OF UNSEASONABLY WARM WEATHER
FRIDAY. THE RIDGE WILL BEGIN TO SLOWLY BREAK DOWN THROUGH THE
WEEKEND AS AN OFFSHORE TROUGH MOVES INLAND. THIS TROUGH WILL BRING
A GRADUAL COOLING TREND AS WELL AS INCREASING CHANCES OF
PRECIPITATION.
&&
.DISCUSSION...
UPDATE...VISIBLE IMAGERY HAS BEGUN TO ROLL IN NOW...AND A LARGE
AMOUNT OF ALTOCUMULUS CASTELLATUS HAS BEEN REVEALED THAT WASN`T
READILY DISCERNIBLE ON THE IR IMAGERY OVERNIGHT. LAPSE RATES ARE
FAIRLY STEEP FROM THE TOP OF THE MORNING INVERSION UP TO 575 MB OR
SO AND AGAIN ABOVE 450 MB...HOWEVER IT SEEMS MOST OF THE ACCUS IS
LIKELY AT THE TOP OF THE LOWER INSTABILITY LEVEL...WHERE THE ONLY
AREA EVEN NEARLY SATURATED ON THE 12Z KOTX SOUNDING
EXISTS...AROUND 600 MB. BELOW THIS LEVEL...DEWPOINT DEPRESSIONS
TOP OUT NEAR 27C...SO A VERY DRY LOWER 400 MB EXISTS TO SAY THE
LEAST. THE RATHER IMPRESSIVE MID-LEVEL LAPSE RATES AND EARLY
MORNING CLOUD SIGNATURES WILL LIKELY ALLOW FOR SOME VIRGA THIS
AFTERNOON AS THE BUILDUPS FLARE A BIT...HOWEVER THE DRY LOWER
ATMOSPHERE WILL ERADICATE ANY PRECIPITATION THAT COMES OUT OF THE
CLOUDS BEFORE IT TOUCHES THE GROUND. ADDITIONALLY...UPPER LEVEL
LIFT IN ASSOCIATION WITH THE LOW COMING INTO THE NORTHERN
CALIFORNIA COAST REMAINS TO OUR SOUTH AND WEST THROUGH THE
DAY...SO WITH A LACK OF ANY SYNOPTIC FORCING...WHATEVER ACTIVITY
THAT MAY INITIATE FROM THE MID-LEVELS WILL LIKELY BE RATHER SHORT
LIVED.
TEMPERATURES FOR TODAY LOOK SIMILAR TO YESTERDAY...WITH THE
EASTERN CWA LIKELY THE WARMEST PART OF THE ENTIRE AREA. ACROSS THE
CASCADES...TIGHT TEMPERATURE GRADIENTS AT 925 AND 850 MB SUGGEST A
DECENT MARINE PUSH TOWARD THE CASCADES...SO TEMPERATURES ALONG THE
CREST ARE LIKELY TO BE THE ONLY ONES IN THE CWA COOLER THAN
YESTERDAY. OTHERWISE...HIGHS APPROACHING RECORD VALUES STILL SEEM
POSSIBLE ACROSS THE NORTHERN ZONES...WITH MUCH OF THE CWA A DOZEN
DEGREES ABOVE NORMAL. /FRIES
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES THROUGH 12Z SAT AS
STRONG RIDGE RESIDES OVER THE INLAND NW TODAY. BY TONIGHT...THE
RIDGE WILL GIVE WAY TO A TROF APPROACHING FROM THE SW...BUT ALL THIS
WILL DO IS GRADUALLY THICKEN AND INCREASE MID AND HI LEVEL CLOUDS
OVERNIGHT. FX
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 87 55 72 50 68 47 / 0 0 30 40 20 20
COEUR D`ALENE 89 53 72 50 66 46 / 0 0 30 50 40 30
PULLMAN 87 51 72 48 68 45 / 0 10 30 30 20 30
LEWISTON 93 62 78 56 74 53 / 0 20 30 30 10 20
COLVILLE 90 48 76 45 69 41 / 0 0 30 50 40 30
SANDPOINT 79 48 71 47 64 44 / 0 0 30 50 50 30
KELLOGG 88 50 70 50 61 46 / 0 10 40 50 50 40
MOSES LAKE 86 56 78 50 75 47 / 0 10 20 10 10 20
WENATCHEE 86 59 76 52 74 51 / 0 10 20 10 10 20
OMAK 88 55 76 48 75 46 / 0 0 20 10 10 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
000
FXUS66 KOTX 191217
AFDOTX
AREA FORECAST DISCUSSION...UPDATED AVIATION SECTION
NATIONAL WEATHER SERVICE SPOKANE WA
512 AM PDT FRI SEP 19 2008
.SYNOPSIS...
A STRONG RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE INLAND
NORTHWEST RESULTING IN ANOTHER DAY OF UNSEASONABLY WARM WEATHER
FRIDAY. THE RIDGE WILL BEGIN TO SLOWLY BREAK DOWN THROUGH THE
WEEKEND AS AN OFFSHORE TROUGH MOVES INLAND. THIS TROUGH WILL BRING
A GRADUAL COOLING TREND AS WELL AS INCREASING CHANCES OF
PRECIPITATION.
&&
.DISCUSSION...
TODAY AND TONIGHT...LOOKS LIKE ANOTHER UNSEASONABLY WARM DAY
AWAITS THE INLAND NW...AS OFFSHORE LOW IS TAKING ITS TIME TO SWING
INLAND. AS OF 09Z...THE LOW WAS CENTERED NEAR 40/128...WHICH WAS
ACCURATELY PORTRAYED BY THE 00Z/06Z MODEL RUNS. BY 00Z THIS
AFTERNOON...ALL THE SHORT RANGE MODELS BRING THIS LOW INTO THE NW
CORNER OF CALIFORNIA. IMPACT OF THIS INLAND SURGE TODAY WILL BE
MINIMAL OVER OUR CWA. LOW-LEVEL THERMAL FIELDS SHOW LITTLE CHANGE VS.
YESTERDAY WHILE SIGNIFICANT MOISTURE AND LIFTING WILL FAIL TO MAKE
IT THIS FAR NORTH. THE MODELS CORRECTLY BACKED OFF ON THE CHANCES
FOR PRECIPITATION OVER OUR CWA THIS AFTERNOON. MODEL CAPES BARELY
REGISTER OVER THE INLAND NW TODAY AND AS SUCH FEEL CHANCES OF
MEASURABLE PRECIPITATION WILL BE NEXT TO NOTHING. THE CLOSEST AREA
OF PRECIPITATION WILL LIKELY FORM OVER NC OREGON WHERE DECENT
DESTABILIZATION COMBINES WITH MODERATE UPPER LEVEL DIFLUENCE. AS
PREVIOUSLY MENTIONED...LOW-LEVEL THERMAL FIELDS VARY LITTLE FROM
YESTERDAY...SUGGESTING ANOTHER DAY OF MAX TEMPS RANGING FROM 10-15
DEGREES ABOVE SEASONAL NORMALS. A FEW LOCATIONS EXTENDING FROM THE
OKANOGAN HIGHLANDS TO THE NORTHERN ID PANHANDLE COULD EVEN SEE
RECORD BREAKING WARMTH.
FOR TONIGHT...THE CHANCES FOR PRECIP SHOULD INCREASE AA BIT AS THE
AFOREMENTIONED 500 MB LOW BEGINS TO PHASE WITH WITH A NORTHERN
STREAM TROF...CURRENTLY CENTERED NEAR 145W. THIS GIVES THE OVERALL
500 MB PATTERN A NEGATIVELY TILTED TROF ORIENTATION. TYPICALLY
NEGATIVELY TILTED TROFS LEAD TO A GOOD CHANCE OF CONVECTION AS THE
ANTECEDENT WARM RIDGE BREAKS DOWN. HOWEVER IN THIS CASE IT LOOKS
LIKE ONE OF THE KEY INGREDIENTS...POTENTIAL INSTABILITY...IS
LACKING. ALSO THERE ARE SIGNS THAT MOST OF THE SIGNIFICANT HEIGHT
FALLS WILL REMAIN BOTTLED UP WELL TO OUR SOUTH. THE GFS IS THE
MOST NORTHERN OF THE SOLUTIONS AND SEEMS TO HAVE ITS QPF FIELDS
TAINTED BY A CONVECTIVE VORT LOBES INITIATING THIS EVENING OVER THE
CENTRAL CASCADES AND NE CORNER OF OREGON. THE DPROG/DT OF THESE
FEATURES IS QUITE SUSPECT. THAT BEING SAID...THE CHANCES FOR
MEASURABLE PRECIP OVERNIGHT LOOK RATHER SMALL...ESPECIALLY
CONSIDERING HOW DRY THE IN SITU AIRMASS IS. FOR NOW WE WILL KEEP
THE BEST CHANCES OF PRECIP OVER OUR EXTREME SE ZONES AND NEAR THE
CASCADES DUE TO THE LIKELY PROXIMITY OF THE MOISTURE PLUME AHEAD
OF THE INCOMING NEGATIVELY TILTED TROF. FX
SATURDAY THROUGH SUNDAY NIGHT...AN UPPER LEVEL TROUGH WILL TAKE ON A
NEGATIVE TILT AS IT SWINGS THROUGH THE REGION OVER THE WEEKEND.
MODELS HAVE BEEN JUMPING AROUND WITH THE TRACK OF THE CORE OF THE
SHORTWAVE ENERGY OVER THE PAST SEVERAL RUNS. 24 HOURS AGO THE TRACK
WAS RIGHT ACROSS THE INLAND NORTHWEST INDICATING A GOOD CHANCE OF
SHOWERS FOR MUCH OF THE FORECAST AREA. NOW THE PAST COUPLE OF RUNS
DROP THE TRACK FARTHER SOUTH WITH LESS OF AN IMPACT ON THE CWA. THE
PREVIOUS FORECAST PACKAGE TRIMMED POPS BACK A BIT ACROSS THE BASIN
AND THE NORTHERN ZONES ON SATURDAY MORNING AND THE LATEST MODEL
TRENDS STILL SUPPORT THIS. THE BEST CHANCE OF SHOWERS WILL BE ACROSS
THE EASTERN ZONES SATURDAY AFTERNOON AND EVENING AS THE TROUGH AXIS
PIVOTS OVER THE REGION. TEMPERATURES WILL BE CONSIDERABLY COOLER ON
SATURDAY COMPARED TO FRIDAYS READINGS THEN CONTINUE THE COOLING
TREND ON SUNDAY AS CLOUDS AND PRECIPITATION LIMIT DAYTIME HEATING.
MONDAY THROUGH THURSDAY...COOL AND SOMEWHAT UNSETTLED CONDITIONS
WILL CONTINUE ACROSS THE REGION THROUGH THE EXTENDED FORECAST
PERIOD. THE THREAT OF PRECIPITATION WILL DIMINISH AS THE REGION
TRANSITIONS TO NORTHWEST FLOW ALOFT BY MONDAY NIGHT WITH SHOWERS
LIMITED TO THE EASTERN ZONES FAVORABLE TO NW UPSLOPE FLOW. AFTER A
COOL START OF THE WORKWEEK TEMPERATURES WILL REBOUND CLOSER TO
SEASONAL NORMALS. /KELCH
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES THROUGH 12Z SAT AS
STRONG RIDGE RESIDES OVER THE INLAND NW TODAY. BY TONIGHT...THE
RIDGE WILL GIVE WAY TO A TROF APPROACHING FROM THE SW...BUT ALL THIS
WILL DO IS GRADUALLY THICKEN AND INCREASE MID AND HI LEVEL CLOUDS
OVERNIGHT. FX
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 87 55 72 50 68 47 / 0 0 30 40 20 20
COEUR D`ALENE 89 53 72 50 66 46 / 0 0 30 50 40 30
PULLMAN 87 51 72 48 68 45 / 0 10 30 30 20 30
LEWISTON 93 62 78 56 74 53 / 0 20 30 30 10 20
COLVILLE 90 48 76 45 69 41 / 0 0 30 50 40 30
SANDPOINT 79 48 71 47 64 44 / 0 0 30 50 50 30
KELLOGG 87 50 70 50 61 46 / 0 10 40 50 50 40
MOSES LAKE 86 56 78 50 75 47 / 0 10 20 10 10 20
WENATCHEE 86 59 76 52 74 51 / 0 10 20 10 10 20
OMAK 88 55 76 48 75 46 / 0 0 20 10 10 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
000
FXUS66 KOTX 191012
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
312 AM PDT FRI SEP 19 2008
.SYNOPSIS...
A STRONG RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE INLAND
NORTHWEST RESULTING IN ANOTHER DAY OF UNSEASONABLY WARM WEATHER
FRIDAY. THE RIDGE WILL BEGIN TO SLOWLY BREAK DOWN THROUGH THE
WEEKEND AS AN OFFSHORE TROUGH MOVES INLAND. THIS TROUGH WILL BRING
A GRADUAL COOLING TREND AS WELL AS INCREASING CHANCES OF
PRECIPITATION.
&&
.DISCUSSION...
TODAY AND TONIGHT...LOOKS LIKE ANOTHER UNSEASONABLY WARM DAY
AWAITS THE INLAND NW...AS OFFSHORE LOW IS TAKING ITS TIME TO SWING
INLAND. AS OF 09Z...THE LOW WAS CENTERED NEAR 40/128...WHICH WAS
ACCURATELY PORTRAYED BY THE 00Z/06Z MODEL RUNS. BY 00Z THIS
AFTERNOON...ALL THE SHORT RANGE MODELS BRING THIS LOW INTO THE NW
CORNER OF CALIFORNIA. IMPACT OF THIS INLAND SURGE TODAY WILL BE
MINIMAL OVER OUR CWA. LOW-LEVEL THERMAL FIELDS SHOW LITTLE CHANGE VS.
YESTERDAY WHILE SIGNIFICANT MOISTURE AND LIFTING WILL FAIL TO MAKE
IT THIS FAR NORTH. THE MODELS CORRECTLY BACKED OFF ON THE CHANCES
FOR PRECIPITATION OVER OUR CWA THIS AFTERNOON. MODEL CAPES BARELY
REGISTER OVER THE INLAND NW TODAY AND AS SUCH FEEL CHANCES OF
MEASURABLE PRECIPITATION WILL BE NEXT TO NOTHING. THE CLOSEST AREA
OF PRECIPITATION WILL LIKELY FORM OVER NC OREGON WHERE DECENT
DESTABILIZATION COMBINES WITH MODERATE UPPER LEVEL DIFLUENCE. AS
PREVIOUSLY MENTIONED...LOW-LEVEL THERMAL FIELDS VARY LITTLE FROM
YESTERDAY...SUGGESTING ANOTHER DAY OF MAX TEMPS RANGING FROM 10-15
DEGREES ABOVE SEASONAL NORMALS. A FEW LOCATIONS EXTENDING FROM THE
OKANOGAN HIGHLANDS TO THE NORTHERN ID PANHANDLE COULD EVEN SEE
RECORD BREAKING WARMTH.
FOR TONIGHT...THE CHANCES FOR PRECIP SHOULD INCREASE AA BIT AS THE
AFOREMENTIONED 500 MB LOW BEGINS TO PHASE WITH WITH A NORTHERN
STREAM TROF...CURRENTLY CENTERED NEAR 145W. THIS GIVES THE OVERALL
500 MB PATTERN A NEGATIVELY TILTED TROF ORIENTATION. TYPICALLY
NEGATIVELY TILTED TROFS LEAD TO A GOOD CHANCE OF CONVECTION AS THE
ANTECEDENT WARM RIDGE BREAKS DOWN. HOWEVER IN THIS CASE IT LOOKS
LIKE ONE OF THE KEY INGREDIENTS...POTENTIAL INSTABILITY...IS
LACKING. ALSO THERE ARE SIGNS THAT MOST OF THE SIGNIFICANT HEIGHT
FALLS WILL REMAIN BOTTLED UP WELL TO OUR SOUTH. THE GFS IS THE
MOST NORTHERN OF THE SOLUTIONS AND SEEMS TO HAVE ITS QPF FIELDS
TAINTED BY A CONVECTIVE VORT LOBES INITIATING THIS EVENING OVER THE
CENTRAL CASCADES AND NE CORNER OF OREGON. THE DPROG/DT OF THESE
FEATURES IS QUITE SUSPECT. THAT BEING SAID...THE CHANCES FOR
MEASURABLE PRECIP OVERNIGHT LOOK RATHER SMALL...ESPECIALLY
CONSIDERING HOW DRY THE IN SITU AIRMASS IS. FOR NOW WE WILL KEEP
THE BEST CHANCES OF PRECIP OVER OUR EXTREME SE ZONES AND NEAR THE
CASCADES DUE TO THE LIKELY PROXIMITY OF THE MOISTURE PLUME AHEAD
OF THE INCOMING NEGATIVELY TILTED TROF. FX
SATURDAY THROUGH SUNDAY NIGHT...AN UPPER LEVEL TROUGH WILL TAKE ON A
NEGATIVE TILT AS IT SWINGS THROUGH THE REGION OVER THE WEEKEND.
MODELS HAVE BEEN JUMPING AROUND WITH THE TRACK OF THE CORE OF THE
SHORTWAVE ENERGY OVER THE PAST SEVERAL RUNS. 24 HOURS AGO THE TRACK
WAS RIGHT ACROSS THE INLAND NORTHWEST INDICATING A GOOD CHANCE OF
SHOWERS FOR MUCH OF THE FORECAST AREA. NOW THE PAST COUPLE OF RUNS
DROP THE TRACK FARTHER SOUTH WITH LESS OF AN IMPACT ON THE CWA. THE
PREVIOUS FORECAST PACKAGE TRIMMED POPS BACK A BIT ACROSS THE BASIN
AND THE NORTHERN ZONES ON SATURDAY MORNING AND THE LATEST MODEL
TRENDS STILL SUPPORT THIS. THE BEST CHANCE OF SHOWERS WILL BE ACROSS
THE EASTERN ZONES SATURDAY AFTERNOON AND EVENING AS THE TROUGH AXIS
PIVOTS OVER THE REGION. TEMPERATURES WILL BE CONSIDERABLY COOLER ON
SATURDAY COMPARED TO FRIDAYS READINGS THEN CONTINUE THE COOLING
TREND ON SUNDAY AS CLOUDS AND PRECIPITATION LIMIT DAYTIME HEATING.
MONDAY THROUGH THURSDAY...COOL AND SOMEWHAT UNSETTLED CONDITIONS
WILL CONTINUE ACROSS THE REGION THROUGH THE EXTENDED FORECAST
PERIOD. THE THREAT OF PRECIPITATION WILL DIMINISH AS THE REGION
TRANSITIONS TO NORTHWEST FLOW ALOFT BY MONDAY NIGHT WITH SHOWERS
LIMITED TO THE EASTERN ZONES FAVORABLE TO NW UPSLOPE FLOW. AFTER A
COOL START OF THE WORKWEEK TEMPERATURES WILL REBOUND CLOSER TO
SEASONAL NORMALS. /KELCH
&&
.AVIATION...
EXPECT MIDDLE AND HI CLOUD CEILINGS TO INCREASE FROM THE SW AS THE
NEXT UPPER LOW NOW OFF THE OREGON COAST MOVES STEADILY NE. THOUGH
PCPN IS NOT EXPECTED THROUGH THIS FCST CYCLE BY 06Z SAT...CEILINGS
SHOULD LOWER TO 10-13K FT AGL AFT 0Z SAT ALONG AND SOUTH OF A LINE
FROM KEAT...TO KMWH AND KLWS. BZ
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 87 55 72 50 68 47 / 0 0 30 40 20 20
COEUR D`ALENE 89 53 72 50 66 46 / 0 0 30 50 40 30
PULLMAN 87 51 72 48 68 45 / 0 10 30 30 20 30
LEWISTON 93 62 78 56 74 53 / 0 20 30 30 10 20
COLVILLE 90 48 76 45 69 41 / 0 0 30 50 40 30
SANDPOINT 79 48 71 47 64 44 / 0 0 30 50 50 30
KELLOGG 87 50 70 50 61 46 / 0 10 40 50 50 40
MOSES LAKE 86 56 78 50 75 47 / 0 10 20 10 10 20
WENATCHEE 86 59 76 52 74 51 / 0 10 20 10 10 20
OMAK 88 55 76 48 75 46 / 0 0 20 10 10 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
000
FXUS66 KPQR 190958
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
256 AM PDT FRI SEP 19 2008
.SYNOPSIS...A PACIFIC WEATHER SYSTEM WILL MOVE INTO NORTHERN
CALIFORNIA FRIDAY AND WEAKEN WITH THE ASSOCIATED TROUGH OF LOW
PRESSURE MOVING INTO THE FORECAST AREA FRIDAY EVENING. THIS WEATHER
SYSTEM WILL SLOWLY MOVE EAST SATURDAY...WITH ANOTHER LOW PRESSURE
SYSTEM FROM THE GULF OF ALASKA DIGGING SOUTH INTO THE FORECAST AREA
BRINGING A FEW SHOWERS TO THE AREA LATE THIS WEEKEND AND EARLY NEXT
WEEK.
&&
.SHORT TERM...AN UPPER LOW OFF THE NORTHERN CALIFORNIA COAST IS
ROTATING HIGHER CLOUDS OVER THE FORECAST AREA EARLY THIS MORNING. A
BREAK IN THE HIGHER CLOUDS IS OFFERING A PEEK A THE LEFTOVER MARINE
STRATUS BELOW. APPEARS FAIRLY SOLID CLOUD COVER OVER THE NORTH COAST
ZONES AND INTO THE WILLAMETTE VALLEY...ROUGHLY I-5 WESTWARD. AS THE
UPPER LOW MOVES FURTHER INLAND OVER NORTHERN CALIFORNIA/SOUTHERN
OREGON EXPECT IT THE AID IN BREAKING UP THE STRATUS. COULD SEE SOME
SHOWERS OVER THE CASCADES AS THE HIGH LEVEL MOISTURE AND SOME
INSTABILITY DEVELOPS THIS AFTERNOON. MODELS ARE WEAKER WITH THE
INSTABILITY SO HAVE DROPPED MENTION OF THUNDERSTORMS OVER THE
CASCADES FOR THIS AFTERNOON AND EARLY EVENING. A WEAK UPPER LEVEL
SHORTWAVE WILL MOVE ACROSS THE FORECAST AREA SATURDAY WITH LOW
CHANCES FOR SHOWERS OVER THE NORTHERN COAST ZONES. A MORE ENERGETIC
UPPER LEVEL TROUGH WILL MOVE INTO THE FORECAST AREA SUNDAY WITH THE
POSSIBILITY OF SOME SHOWERS WITH THE BEST PROSPECTS ON THE NORTH
COAST/COAST RANGE AND WILLAPA HILLS.
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...LONG RANGE
MODELS CONTINUE TO SHOW A LOT OF VARIABILITY IN THE EXTENDED TIME
PERIOD. SHOWERS TAPER OFF MONDAY AS THE UPPER LEVEL TROUGH MOVES OFF
TO THE EAST OF THE FORECAST AREA...WITH A FEW SHOWERS LINGERING OVER
THE CASCADES. CONFIDENCE IS LOW FOR THE REMAINDER OF THE FORECAST AS
MODELS TREND TOWARD 180 DEGREES OUT OF PHASE AT TIMES. WILLSON
&&
.AVIATION...AREAS OF MVFR MARINE STRATUS SLOWLY EXPANDING EARLY
TODAY...BUT IMPEDED BY AN UPPER LEVEL SYSTEM APPROACHING THE
NORTHERN CALIFORNIA COAST WHICH HAS PROVIDED BETTER MIXING OF THE
MARINE LAYER. HOWEVER THERE SHOULD BE ENOUGH COOLING IN THE LOW
LEVELS TO ALLOW STRATUS TO REDEVELOP IN MOST AREAS BY DAYBREAK. SLOW
LIFTING/BREAKING UP OF THE MARINE MVFR DECK EXPECTED BY MIDDAY/EARLY
AFTERNOON. RW
KPDX AND APPROACHES...MVFR CIGS EXPECTED TO REMAIN IN PLACE THROUGH
MIDDAY...WITH SLOW IMPROVEMENT TO VFR EXPECTED BY 21Z.
&&
.MARINE...WEAK HIGH PRESSURE OVER THE COASTAL WATERS WILL CAUSE
LIGHT WINDS/SEAS TO CONTINUE INTO SAT. SOME 4-5 FT W-SW SWELL MAY
SNEAK INTO SOUTHERN WATERS TODAY FROM THE LOW PRES SYSTEM
APPROACHING THE NORTHERN CALIFORNIA COAST. OTHERWISE SEAS SHOULD BE
LESS THAN 5 FT. THE LIGHT SWELL IS ALLOWING THE COLUMBIA RIVER BAR
TO REMAIN FREE OF ADVISORIES DESPITE THE STRONG ASTRONOMICAL EVENING
EBB CURRENTS THIS WEEK. INCREASING NW WINDS/SEAS LIKELY LATER SUN
AND MON AS HIGH PRES BUILDS IN BEHIND A WEAK GULF OF ALASKA COLD
FRONT. RW
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR/WA...NONE.
&&
.PRELIMINARY POINT POPS (PROBABILITY OF MEASURABLE PRECIPITATION)
AST 11122 PDX 11112 SLE 11112 EUG 11112
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KSEW 190946 AAA
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
230 AM PDT FRI SEP 19 2008
.SYNOPSIS...ONSHORE FLOW WILL KEEP CLOUDS AND PATCHY DRIZZLE OVER
WESTERN WASHINGTON THIS MORNING. A WEAK WEATHER SYSTEM WILL MOVE
THROUGH THE REGION THIS WEEKEND. A SHARPER COOLER UPPER LEVEL TROUGH
WILL ARRIVE SUNDAY NIGHT. AN UNSETTLED WEATHER PATTERN IS LIKELY
NEXT WEEK.
&&
.SHORT TERM...THE STRATUS MAY BREAK UP THIS AFTERNOON BUT IT SHOULD
STILL STAY ON THE COOL SIDE TODAY WITH MOST PLACES IN THE 60S. FOR
THE MORNING...WITH A LITTLE DRIZZLE AT NUW I HAVE PUT PATCHY MORNING
DRIZZLE INTO THE FCST. THE CHANCE OF MEASURABLE PRECIP INCREASES A
BIT OVER THE WEEKEND BUT THE TROF MOSTLY MOVES THRU OREGON AND OVER
WA IS WEAK SO POPS ARE IN THE CHANCE CATEGORY. THE NAM LOOKS SIMILAR
TO YESTERDAY GENERATING A BAND OF PRECIP OFF THE CASCADES EARLY SAT
MORNING THEN STREAKING IT NNW THRU SAT MORNING SO THAT MIGHT BE
WORTH LIKELY POPS IF IT PERSISTS IN TODAYS MODEL RUN. THE CHANCE FOR
PRECIP IS PROBABLY THE GREATEST LATE IN THE WEEKEND AS THE COOLEST
AIR ALOFT AND SHARPER TROF ARRIVES...PROBABLY SUN NITE. 19
.LONG TERM...THE LATEST GFS HAS HEIGHTS RISING 100M MON NITE AND TUE
WITH NO PRECIP...BUT DECENT ZONAL FLOW. A SYSTEM SPLIT UP BETWEEN
THE SRN AND NRN STREAMS SHOWS UP TUE NITE BUT IS MUCH DRIER THAN
YDYS SOLUTION BUT I THINK WILL PROBABLY TREND BACK TO LOOKING WET.
THE STRENGTH OF THE JET SUGGESTS WE ARE HEADING BACK INTO AN ACTIVE
WEATHER PATTERN. THE WRF EXTENSION SHOWS A LOT OF SHOWER ACTIVITY
AND A PSCZ ON MONDAY IN THE FAIRLY STRONG ONSHORE FLOW BEHIND THE
TROF...THE 84HR WRF VALID 12Z MON LOOKS GOOD FOR SHOWERS AND PSCZ.
THEN TUE IS MOSTLY DRY EXCEPT FOR MAYBE SCT SHOWERS IN THE
MOUNTAINS. THE UW`S WRF EXTENSION HAS SGFNT RAIN OVER SW WA WED AS A
1016MB LOW REACHES THE SOUTH COAST...THAT IS PROBABLY THE REMNANTS
OF OLD TROPICAL MOISTURE WHICH HAS CROSSED THE PAC...IT IS THE SRN
STREAM SYSTEM IN THE GFS...BUT THE MODELS DO NOT SHOW IT DEEPENING
AS IT COMES IN. STILL...FOR NOW THE BEST CHANCE FOR PRECIP LOOKS TO
BE MON WITH SHOWERS AND AND WED FOR A RAIN EVENT. FCST HASN`T YET
BEEN PUSHED THAT DIRECTION. 19
&&
.AVIATION...A WEAKENING UPPER LEVEL RIDGE WILL REMAIN IN PLACE OVER
THE NORTHWEST THROUGH TODAY BEFORE GIVING WAY TO A WEAK TROUGH. THE
FLOW ALOFT WILL BE LIGHT SOUTH TO SOUTHEAST. THE SURFACE PRESSURE
GRADIENT ACROSS THE STATE WILL INCREASE OVER THE NEXT 24 HOURS
RESULTING IN STEADILY INCREASING ONSHORE FLOW.
THE DEEP MARINE LAYER WILL REMAIN ENTRENCHED OVER WESTERN WASHINGTON
AND LITTLE CHANGE IS EXPECTED OVER THE NEXT 24 HOURS WITH RESPECT TO
THIS MARINE LAYER. THEREFORE PLENTY OF STRATUS TO DEAL WITH INTO
SATURDAY. SOME BREAKUP IN THE LOW CLOUD COVER IS POSSIBLE TONIGHT
AND SATURDAY AS THE WEAK UPPER TROUGH PASSES OVERHEAD.
KSEA...LITTLE CHANGE IN THE SKY COVER EXPECTED THROUGH MOST OF THE
DAY. THE LOW CLOUD DECK WILL GRADUALLY LIFT THROUGH THE DAY AND
POSSIBLE BREAKUP SOME THIS AFTERNOON. HOWEVER...IT WILL LIKELY FILL
BACK IN THIS EVENING. WITH INCREASING NEGATIVE GRADIENTS IN THE
SOUND EXPECT A LIGHT NORTH WIND TO DEVELOP THIS MORNING AND REMAIN
INTO THE AFTERNOON HOURS. CERNIGLIA
&&
MARINE...ONSHORE FLOW WILL INCREASE THROUGH THE DAY TODAY AS THE
PRESSURE GRADIENT INCREASES ACROSS THE STATE. THE MAIN RESULT WILL
BE ENHANCED FLOW DOWN THE STRAIT LATER THIS AFTERNOON AND EVENING.
LIGHT TO MODERATE ONSHORE FLOW WILL CONTINUE THROUGH THE WEEKEND AS
A SERIES OF UPPER TROUGH PASS ACROSS THE REGION. A WEAKENING FRONT
AND POSSIBLE WEAK SURFACE LOW CENTER IS EXPECTED TO APPROACH THE
COAST TUE. CERNIGLIA
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.
&&
$$
WEATHER.GOV/SEATTLE
000
FXUS66 KSEW 190905
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
230 AM PDT FRI SEP 19 2008
.SYNOPSIS...ONSHORE FLOW WILL KEEP CLOUDS AND PATCHY DRIZZLE OVER
WESTERN WASHINGTON THIS MORNING. A WEAK WEATHER SYSTEM WILL MOVE
THROUGH THE REGION THIS WEEKEND. A SHARPER COOLER UPPER LEVEL TROUGH
WILL ARRIVE SUNDAY NIGHT. AN UNSETTLED WEATHER PATTERN IS LIKELY
NEXT WEEK.
&&
.SHORT TERM...THE STRATUS MAY BREAK UP THIS AFTERNOON BUT IT SHOULD
STILL STAY ON THE COOL SIDE TODAY WITH MOST PLACES IN THE 60S. FOR
THE MORNING...WITH A LITTLE DRIZZLE AT NUW I HAVE PUT PATCHY MORNING
DRIZZLE INTO THE FCST. THE CHANCE OF MEASURABLE PRECIP INCREASES A
BIT OVER THE WEEKEND BUT THE TROF MOSTLY MOVES THRU OREGON AND OVER
WA IS WEAK SO POPS ARE IN THE CHANCE CATEGORY. THE NAM LOOKS SIMILAR
TO YESTERDAY GENERATING A BAND OF PRECIP OFF THE CASCADES AROUND
MIDNIGHT SAT NIGHT AND THEN STREAKING IT NNW THRU SAT MORNING SO
THAT MIGHT BE WORTH LIKELY POPS IF IT PERSISTS IN TODAYS MODEL RUN.
THE CHANCE FOR PRECIP IS PROBABLY THE GREATEST LATE IN THE WEEKEND
AS THE COOLEST AIR ALOFT AND SHARPER TROF ARRIVES...PROBABLY SUN
NITE. 19
.LONG TERM...THE LATEST GFS HAS HEIGHTS RISING 100M MON NITE AND TUE
WITH NO PRECIP...BUT DECENT ZONAL FLOW. A SYSTEM SPLIT UP BETWEEN
THE SRN AND NRN STREAMS SHOWS UP TUE NITE BUT IS MUCH DRIER THAN
YDYS SOLUTION BUT I THINK WILL PROBABLY TREND BACK TO LOOKING WET.
THE STRENGTH OF THE JET SUGGESTS WE ARE HEADING BACK INTO AN ACTIVE
WEATHER PATTERN. 19
&&
.AVIATION...A WEAKENING UPPER LEVEL RIDGE WILL REMAIN IN PLACE OVER
THE NORTHWEST THROUGH TODAY BEFORE GIVING WAY TO A WEAK TROUGH. THE
FLOW ALOFT WILL BE LIGHT SOUTH TO SOUTHEAST. THE SURFACE PRESSURE
GRADIENT ACROSS THE STATE WILL INCREASE OVER THE NEXT 24 HOURS
RESULTING IN STEADILY INCREASING ONSHORE FLOW.
THE DEEP MARINE LAYER WILL REMAIN ENTRENCHED OVER WESTERN WASHINGTON
AND LITTLE CHANGE IS EXPECTED OVER THE NEXT 24 HOURS WITH RESPECT TO
THIS MARINE LAYER. THEREFORE PLENTY OF STRATUS TO DEAL WITH INTO
SATURDAY. SOME BREAKUP IN THE LOW CLOUD COVER IS POSSIBLE TONIGHT
AND SATURDAY AS THE WEAK UPPER TROUGH PASSES OVERHEAD.
KSEA...LITTLE CHANGE IN THE SKY COVER EXPECTED THROUGH MOST OF THE
DAY. THE LOW CLOUD DECK WILL GRADUALLY LIFT THROUGH THE DAY AND
POSSIBLE BREAKUP SOME THIS AFTERNOON. HOWEVER...IT WILL LIKELY FILL
BACK IN THIS EVENING. WITH INCREASING NEGATIVE GRADIENTS IN THE
SOUND EXPECT A LIGHT NORTH WIND TO DEVELOP THIS MORNING AND REMAIN
INTO THE AFTERNOON HOURS. CERNIGLIA
&&
MARINE...ONSHORE FLOW WILL INCREASE THROUGH THE DAY TODAY AS THE
PRESSURE GRADIENT INCREASES ACROSS THE STATE. THE MAIN RESULT WILL
BE ENHANCED FLOW DOWN THE STRAIT LATER THIS AFTERNOON AND EVENING.
LIGHT TO MODERATE ONSHORE FLOW WILL CONTINUE THROUGH THE WEEKEND AS
A SERIES OF UPPER TROUGH PASS ACROSS THE REGION. A WEAKENING FRONT
AND POSSIBLE WEAK SURFACE LOW CENTER IS EXPECTED TO APPROACH THE
COAST TUE. CERNIGLIA
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.
&&
$$
WEATHER.GOV/SEATTLE
000
FXUS66 KSEW 190901
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
200 AM PDT FRI SEP 19 2008
.SYNOPSIS...ONSHORE FLOW WILL CONTINUE...RESULTING IN QUITE A BIT OF
CLOUD COVER ACROSS MUCH OF THE AREA THROUGH FRIDAY. MEANWHILE...HIGH
PRESSURE ALOFT WILL MOVE EAST FRIDAY NIGHT...ALLOWING A WEAK LOW
PRESSURE SYSTEM TO MOVE OVER THE REGION ON SATURDAY. THIS WILL BE
FOLLOWED BY ANOTHER SYSTEM ON SUNDAY. THUS EXPECT UNSETTLED WEATHER
CONDITIONS FOR THIS WEEKEND.
&&
.SHORT TERM...THE STRATUS MAY BREAK UP THIS AFTERNOON (PIC1) BUT IT
SHOULD STILL STAY ON THE COOL SIDE TODAY WITH MOST PLACES IN THE
60S. FOR THE MORNING...WITH A LITTLE DRIZZLE AT NUW I HAVE PUT
PATCHY MORNING DRIZZLE INTO THE FCST. THE CHANCE OF MEASURABLE
PRECIP INCREASES A BIT OVER THE WEEKEND BUT THE TROF MOSTLY MOVES
THRU OREGON AND OVER WA IS WEAK SO POPS ARE IN THE CHANCE CATEGORY.
THE NAM LOOKS SIMILAR TO YESTERDAY GENERATING A BAND OF PRECIP OFF
THE CASCADES AROUND MIDNIGHT SAT NIGHT AND THEN STREAKING IT NNW
THRU SAT MORNING SO THAT MIGHT BE WORTH LIKELY POPS IF IT PERSISTS
IN TODAYS MODEL RUN (PIC2). THE CHANCE FOR PRECIP IS PROBABLY THE
GREATEST LATE IN THE WEEKEND AS THE COOLEST AIR ALOFT AND SHARPER
TROF ARRIVES...PROBABLY SUN NITE (PIC3). 19
.LONG TERM...THE LATEST GFS HAS HEIGHTS RISING 100M MON NITE AND TUE
WITH NO PRECIP...BUT DECENT ZONAL FLOW. A SYSTEM SPLIT UP BETWEEN
THE SRN AND NRN STREAMS SHOWS UP TUE NITE (PIC4) (PIC5) THAT IS MUCH
DRIER THAN YDYS SOLUTION BUT I THINK WILL PROBABLY TREND BACK TO
LOOKING WET. THE STRENGTH OF THE JET SUGGESTS WE ARE HEADING BACK
INTO AN ACTIVE WEATHER PATTERN (PIC6). 19
&&
.AVIATION...A WEAKENING UPPER LEVEL RIDGE WILL REMAIN IN PLACE OVER
THE NORTHWEST THROUGH TODAY (PIC10) BEFORE GIVING WAY TO A WEAK
TROUGH (PIC11). THE FLOW ALOFT WILL BE LIGHT SOUTH TO SOUTHEAST. THE
SURFACE PRESSURE GRADIENT ACROSS THE STATE WILL INCREASE OVER THE
NEXT 24 HOURS (PIC13)(PIC14) RESULTING IN STEADILY INCREASING
ONSHORE FLOW.
THE DEEP MARINE LAYER WILL REMAIN ENTRENCHED OVER WESTERN WASHINGTON
AND LITTLE CHANGE IS EXPECTED OVER THE NEXT 24 HOURS WITH RESPECT TO
THIS MARINE LAYER. THEREFORE PLENTY OF STRATUS TO DEAL WITH INTO
SATURDAY. SOME BREAKUP IN THE LOW CLOUD COVER IS POSSIBLE TONIGHT
AND SATURDAY AS THE WEAK UPPER TROUGH PASSES OVERHEAD.
KSEA...LITTLE CHANGE IN THE SKY COVER EXPECTED THROUGH MOST OF THE
DAY. THE LOW CLOUD DECK WILL GRADUALLY LIFT THROUGH THE DAY AND
POSSIBLE BREAKUP SOME THIS AFTERNOON. HOWEVER...IT WILL LIKELY FILL
BACK IN THIS EVENING. WITH INCREASING NEGATIVE GRADIENTS IN THE
SOUND EXPECT A LIGHT NORTH WIND TO DEVELOP THIS MORNING AND REMAIN
INTO THE AFTERNOON HOURS. CERNIGLIA
&&
MARINE...ONSHORE FLOW WILL INCREASE THROUGH THE DAY TODAY
(PIC13)(PIC14) AS THE PRESSURE GRADIENT INCREASES ACROSS THE STATE.
THE MAIN RESULT WILL BE ENHANCED FLOW DOWN THE STRAIT LATER THIS
AFTERNOON AND EVENING. LIGHT TO MODERATE ONSHORE FLOW WILL CONTINUE
THROUGH THE WEEKEND AS A SERIES OF UPPER TROUGH PASS ACROSS THE
REGION. A WEAKENING FRONT AND POSSIBLE WEAK SURFACE LOW CENTER IS
EXPECTED TO APPROACH THE COAST TUE. CERNIGLIA
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT.
&&
$$
WEATHER.GOV/SEATTLE
000
FXUS66 KOTX 190506 AAA
AFDOTX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SPOKANE WA
1006 PM PDT THU SEP 18 2008
...UPDATED AVIATION...
.SYNOPSIS...
A STRONG RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE INLAND
NORTHWEST RESULTING IN ANOTHER DAY OF UNSEASONABLY WARM WEATHER
FRIDAY. THE RIDGE WILL BEGIN TO SLOWLY BREAK DOWN BY LATE FRIDAY
AND THROUGH THE WEEKEND AS AN OFFSHORE TROUGH MOVES INLAND. THIS
TROUGH WILL BRING A GRADUAL COOLING TREND AS WELL AS INCREASING
CHANCES OF PRECIPITATION.
&&
.PREV DISCUSSION... /ISSUED 420 PM PDT THU SEP 18 2008/
TONIGHT THROUGH SUNDAY...MODELS IN GOOD AGREEMENT THROUGH THE NEXT
12 HOURS. UPPER LEVEL RIDGE CONTINUES TO DOMINATE THE WEATHER FOR
THE NEXT 12-24 HOURS. THE THERMAL TROUGH HASN`T MOVED MUCH OVER THE
LAST 24 HOURS AND WON`T MOVE MUCH OVER THE NEXT 24 HOURS. THIS
TRANSLATES TO CONTINUED MOSTLY CLEAR SKIES...WITH JUST SOME HIGH
CLOUDS MOVING ACROSS. MIDSLOPE TEMPERATURES WILL ONCE AGAIN BE WARM
OVERNIGHT WITH POOR RH RECOVERIES...AND THE PROTECTED VALLEYS ACROSS
THE NORTH WILL BE COOL. THE MAIN FORECAST CHALLENGE TODAY IS JUST
WHAT TO EXPECT THIS WEEKEND. THIS MORNING THE GFS AND ECMWF AGREED
ON THE IDEA OF SWINGING A NEGATIVELY TILTED TROUGH ACROSS US
SATURDAY AND SATURDAY NIGHT RESULTING IN SOME DECENT RAIN FOR MOST
OF EASTERN WA AND NORTH ID. NOW THE 12Z RUNS HAVE FLIPPED BACK TO
THE IDEAS THEY HAD A DAY AND A HALF AGO OF KEEPING THIS CLOSED LOW
TO THE SOUTH...AND TAKING IT ACROSS SOUTHERN OREGON AND NORTHERN
CA/NV. MODELS TYPICALLY HAVE THESE KINDS OF PROBLEMS DURING THE
TRANSITION PERIOD FROM SUMMER TO FALL...AND GIVEN WE ARE GOING FROM
AN UNUSUALLY WARM STATIONARY RIDGE TO A COOL PROGRESSIVE TROUGH-LIKE
SCENARIO I AM NOT SURPRISED BY THE POOR RUN TO RUN CONSISTENCY. THE
12Z CANADIAN IS SIMILAR TO THE 12Z ECMWF AND GFS IN KEEPING THE LOW
TO THE SOUTH...AND HAVE TRIED TO TREND THE FORECAST IN THAT
DIRECTION. WHAT DOES THIS MEAN? WELL THE BEST CHANCE FOR SHOWERS
LOOKS TO BE SATURDAY NIGHT AND SUNDAY ACROSS EXTREME EASTERN WA AND
NORTH ID. GIVEN THE PATH OF THE LOW HAVE ALSO TAKEN OUT ALL MENTION
OF THUNDER. TEMPERATURES GO FROM 10-15 DEGREES ABOVE AVERAGE FRIDAY
TO RIGHT AROUND AVERAGE BY SUNDAY. /NISBET
SUN NIGHT TO MON NIGHT...THE NW REMAINS UNDER A LONG-WAVE TROUGH.
A MODERATE SHORT-WAVE PIVOTS ACROSS THE CWA SUN NIGHT...FOLLOWED
BY A COUPLE WEAKER WAVES LATE MON/MON NIGHT WITH A WNW FLOW. LOOK
FOR A CONTINUE RISK FOR PRECIP OVER THE CASCADES AND ERN THIRD OF
THE CWA. CHANCES WILL BE BEST SUN NIGHT...DWINDLING TO MTN ZONES
MON NIGHT. TUES...HIGH PRESSURE BRIEFLY BUILDS IN. JUST A SLIGHT
CHANCE FOR SHOWERS LINGERS IN THE MTNS. TUE NIGHT TO WED NIGHT...
A WARM FRONT LIFTS THROUGH...BRINGING A RISK FOR SHOWERS TO THE
CASCADES AND MTN ZONES...WHILE INCREASING CLOUDS OVER THE
REMAINDER OF THE CWA. THURSDAY...AN UPPER TROUGH/COLD FRONT PUSHES
TOWARD THE NW. THE 12Z GFS BRINGS IT INTO IDAHO ON THURSDAY. THE 12Z
ECMWF HOLDS IT OVER THE PACIFIC AND KEEPS A RIDGE OVER THE REGION.
GIVEN THE UNCERTAINTY...THERE WILL BE MAINLY A SLIGHT CHANCE FOR
SHOWERS IN THE VALLEYS AND CHANCE POPS IN THE MTNS. TEMPS EXPECTED
TO BE BELOW NORMAL AT THE START OF THE PERIOD...WARMING NEAR AVG BY
WEDNESDAY. THIS IS SUPPORTED BY 850 TEMPS NEAR 5 DEG C AND 1000/500
THICKNESSES NEAR 543-547 DAM MONDAY...MODERATING TOWARD THE LOWER
TEENS AND 560 DAM BY THURSDAY RESPECTIVELY. /JCOTE
&&
.AVIATION...
EXPECT MIDDLE AND HI CLOUD CEILINGS TO INCREASE FROM THE SW AS THE
NEXT UPPER LOW NOW OFF THE OREGON COAST MOVES STEADILY NE. THOUGH
PCPN IS NOT EXPECTED THROUGH THIS FCST CYCLE BY 06Z SAT...CEILINGS
SHOULD LOWER TO 10-13K FT AGL AFT 0Z SAT ALONG AND SOUTH OF A LINE
FROM KEAT...TO KMWH AND KLWS. BZ
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 54 87 56 72 49 69 / 0 0 0 30 40 20
COEUR D`ALENE 49 88 52 71 50 67 / 0 0 0 30 50 40
PULLMAN 49 88 51 72 49 69 / 0 0 20 30 30 20
LEWISTON 54 91 61 78 56 74 / 0 10 20 30 30 10
COLVILLE 44 86 42 74 45 71 / 0 0 0 30 50 30
SANDPOINT 41 81 45 70 48 63 / 0 0 0 30 50 50
KELLOGG 50 87 46 68 48 62 / 0 10 10 40 50 50
MOSES LAKE 52 87 57 76 51 76 / 0 0 10 20 10 10
WENATCHEE 57 85 57 75 52 75 / 0 0 10 20 10 10
OMAK 49 89 53 77 47 76 / 0 0 0 20 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
000
FXUS66 KSEW 190431
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
930 PM PDT THU SEP 18 2008
.SYNOPSIS...ONSHORE FLOW WILL CONTINUE...RESULTING IN QUITE A BIT OF
CLOUD COVER ACROSS MUCH OF THE AREA THROUGH FRIDAY. MEANWHILE...HIGH
PRESSURE ALOFT WILL MOVE EAST FRIDAY NIGHT...ALLOWING A WEAK LOW
PRESSURE SYSTEM TO MOVE OVER THE REGION ON SATURDAY. THIS WILL BE
FOLLOWED BY ANOTHER SYSTEM ON SUNDAY. THUS EXPECT UNSETTLED WEATHER
CONDITIONS FOR THIS WEEKEND.
&&
.SHORT TERM...
THE LOW CLOUDS STUBBORNLY PERSISTED OVER MUCH OF THE AREA DESPITE
FLAT OR WEAK OFFSHORE FLOW. THE TOPS WERE RUNNING NEAR 4500 FT...
HENCE THE CLOUDS IN THE CASCADE PASSES. LIGHT FLOW COMBINED WITH A
FAIRLY STRONG TEMP INVERSION PREVENTED MUCH MIXING TODAY...RESULTING
IN LACK OF SUNSHINE AT MANY AREAS AS WELL AS NOTICEABLY COOLER
TEMPS. FOR EXAMPLE...SEA-TAC WAS FOURTEEN DEGREES COOLER THAN
YESTERDAY WITH A HIGH OF ONLY 60 DEGREES. THE NORMAL HIGH FOR TODAY
IS 69 DEGREES.
MEANWHILE...AN UPPER RIDGE WITH THE AXIS OVER THE INTERIOR W WILL
MAINTAIN A SLY FLOW ALOFT OVER THE AREA THRU FRI. AS FAR AS THE
SENSIBLE WEATHER WAS CONCERNED...IT SHOULD BE FAIRLY SIMILAR TO
TODAY. ALTHOUGH THERE MAY BE PEAKS OF SUNSHINE ACROSS THE INTERIOR
LOWLANDS IN THE AFTERNOON DUE TO SOME INCREASE IN MIXING. THIS
SHOULD RESULT IN DAYTIME TEMPS CLOSER TO NORMAL.
THE UPPER RIDGE WILL FINALLY SHIFT FARTHER EWD FRI NIGHT...ALLOWING
AN UPPER TROF TO MOVE OVER THE REGION. THIS TROF WILL BRING A THREAT
OF SHOWERS TO THE CWA LATE FRI NIGHT AND SATURDAY. THE ONSHORE
GRADIENT WILL ALSO TIGHTEN ON SATURDAY...SO THERE WAS A QUESTION AS
TO HOW SUNSHINE WILL ACTUALLY BE PRESENT.
EXPECT ANOTHER UPPER TROF TO DIG SWD ACROSS THE AREA ON SUNDAY...
THEREBY KEEPING CONDITIONS COOL AND UNSETTLED.
.LONG TERM FROM THE PREV DISCUSSION...SHOWER CHANCE CONTINUES MONDAY
OVER CERTAIN AREAS. A STRONGER SYSTEM ARRIVES TUESDAY THROUGH
THURSDAY THOUGH IT LOOKS LIKE THE FOCUS WILL BE IN BRITISH COLUMBIA.
IF THE UPPER RIDGE BUILDS A LITTLE MORE THEN POPS CAN BE REMOVED FOR
THIS PERIOD EXCEPT FOR THE FAR NORTH. RIGHT NOW MOS POPS ARE IN THE
CHANCE CATEGORY AND IT SEEMS OK TO KEEP POPS IN THE FORECAST. SLOW
WARMING TREND IF THE RIDGE BUILDS. BURKE
&&
.AVIATION...A WEAKENING UPPER LEVEL RIDGE REMAINS IN PLACE OVER THE
NORTHWEST WITH SOUTHERLY FLOW ALOFT. WEAK SURFACE HIGH PRESSURE JUST
OFFSHORE WILL MAINTAIN THE ONSHORE FLOW THROUGH FRIDAY.
DEEP MARINE LAYER REMAINS FIRMLY ENTRENCHED OVER WESTERN WASHINGTON
AND LITTLE CHANGE IS EXPECTED OVER THE NEXT 24 HOURS WITH RESPECT TO
THE MARINE LAYER. THEREFORE PLENTY OF STRATUS TO DEAL WITH INTO
SATURDAY WITH GENERALLY LIGHT WINDS.
KSEA...LITTLE CHANGE IN THE SKY COVER THIS EVENING WITH MVFR CIGS IN
LOW STRATUS PERSISTING. WINDS WILL BR LIGHT AND VARIABLE. BRIEF
BREAK IN THE STRATUS POSSIBLE FRI AFTERNOON. CERNIGLIA
&&
MARINE...ONSHORE FLOW WILL PERSIST OVER W WA TONIGHT WITH HI PRES
ALONG THE COAST AND LOW PRES EAST OF THE CASCADES. WITH PRESSURE
GRADIENTS DIMINISHING TONIGHT WINDS WILL BECOME LIGHT. ONSHORE
PRESSURE GRADIENTS WILL INCREASE OVER THE WEEKEND AFFECTING MAINLY
THE STRAIT WITH SCA WINDS LIKELY LATE IN THE AFTERNOON AND EARLY IN
THE EVENING HOURS. CERNIGLIA
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA.
$$
WEATHER.GOV/SEATTLE
000
FXUS66 KPQR 190353
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
900 PM PDT THU SEP 18 2008
.SYNOPSIS...A PACIFIC WEATHER SYSTEM WILL MOVE INTO NORTHERN
CALIFORNIA FRIDAY AND WEAKEN WITH THE ASSOCIATED TROUGH OF LOW
PRESSURE MOVING INTO THE FORECAST AREA FRIDAY EVENING. THIS WEATHER
SYSTEM WILL SLOWLY MOVE EAST SATURDAY...WITH ANOTHER LOW PRESSURE
SYSTEM FROM THE GULF OF ALASKA DIGGING SOUTH INTO THE FORECAST AREA
BRINGING A FEW SHOWERS TO THE AREA LATE THIS WEEKEND AND EARLY NEXT
WEEK.
&&
.SHORT TERM...SURFACE OBSERVATIONS STILL SHOW LOW CLOUDS OVER
THE NORTHERN ZONES...HOWEVER LOW CLOUDS ARE BEING OBSCURED ON
SATELLITE IMAGERY LOOPS BY MID AND HIGH CLOUDS ROTATING AROUND AN
OFFSHORE LOW PRESSURE CENTER NEAR 42N 132W. THE LOW IS MOVING SLOWLY
TOWARD THE SOUTHEAST AND IS EXPECTED TO MOVE ONTO THE NORTHERN
CALIFORNIA COAST FRIDAY AFTERNOON AND WEAKEN WITH SHOWERS OVER THE
CASCADES. COULD POSSIBLY SEE A THUNDERSTORM NEAR THE CREST OF THE
LANE COUNTY CASCADES UNDER DIFFLUENT FLOW ALOFT FRI AND FRI EVENING
AS THE UPPER LEVELS COOL AND LAPSE RATES STEEPEN THERE. STEERING FLOW
COULD BRING SOME CELLS FROM CENTRAL OREGON WHERE LOWER LAYERS WILL BE
WARMER AND ROTATE THEM BACK WEST TO THE CASCADES CREST.
THE ASSOCIATED UPPER LEVEL TROUGH WILL MOVE ACROSS THE FORECAST AREA
FRIDAY NIGHT/SATURDAY. EXPECT A SLIGHT CHANCE OF SHOWERS OVER THE
NORTHERN ZONES SATURDAY AS THE UPPER LEVEL TROUGH MOVES THROUGH THE
AREA.
AN UPPER LEVEL TROUGH WILL MOVE INTO THE FORECAST AREA SUNDAY WITH
THE POSSIBILITY OF SOME SHOWERS AND THE BEST PROSPECTS ON THE NORTH
COAST RANGE AND WILLAPA HILLS. LIKENS
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...LONG RANGE
MODELS CONTINUE TO SHOW A LOT OF VARIABILITY IN THE EXTENDED TIME
PERIOD. SHOWERS TAPER OFF MONDAY AS THE UPPER LEVEL TROUGH MOVES OFF
TO THE EAST OF THE FORECAST AREA...WITH A FEW SHOWERS LINGERING OVER
THE CASCADES. CONFIDENCE IS LOW FOR THE REMAINDER OF THE FORECAST AS
MODELS TREND TOWARD 180 DEGREES OUT OF PHASE AT TIMES. WILLSON
&&
.AVIATION...MVFR MARINE STRATUS HELD ACROSS THE PORTLAND METRO
TERMINALS ALL DAY THURSDAY...WHILE CLEARING AT KEUG/KSLE/KONP.
SUSPECT LOW CLOUDS WILL BE SLOW TO REFORM IN THE AREAS THAT CLEARED
OUT TODAY...AS THE UPPER LEVEL SYSTEM APPROACHES NORTHERN CALIFORNIA
PROVIDES BETTER MIXING OF THE MARINE LAYER. HOWEVER EVENTUALLY THERE
SHOULD BE ENOUGH COOLING IN THE LOW LEVELS TO ALLOW STRATUS TO
REDEVELOP IN MOST AREAS BY DAYBREAK. FURTHER NORTH...MVFR CIGS
SHOULD LINGER THROUGH FRI MORNING...WITH SLOW LIFTING/BREAKING UP OF
THE MARINE MVFR DECK EXPECTED BY MIDDAY/EARLY AFTERNOON. WEAGLE
KPDX AND APPROACHES...MVFR CIGS EXPECTED TO REMAIN IN PLACE THROUGH
MIDDAY FRIDAY...WITH SLOW IMPROVEMENT TO VFR EXPECTED BY 21Z.
&&
.MARINE...WEAK HIGH PRESSURE OVER THE COASTAL WATERS WILL CAUSE
LIGHT WINDS/SEAS TO CONTINUE INTO SATURDAY. SOME 4-5 FT W-SW SWELL
MAY SNEAK INTO SOUTHERN WATERS FRIDAY FROM THE LOW PRESSURE SYSTEM
APPROACHING THE NORTHERN CALIFORNIA COAST. OTHERWISE SEAS SHOULD BE
LESS THAN 5 FT. THE LIGHT SWELL IS ALLOWING THE COLUMBIA RIVER BAR
TO REMAIN FREE OF ADVISORIES DESPITE THE STRONG ASTRONOMICAL 3-4 KT
EVENING EBB CURRENTS THIS WEEK. INCREASING NW WINDS/SEAS LIKELY
SUN/MON AS HIGH PRESSURE BUILDS IN BEHIND A WEAK GULF OF ALASKA COLD
FRONT. WEAGLE
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR/WA...NONE.
&&
.PRELIMINARY POINT POPS (PROBABILITY OF MEASURABLE PRECIPITATION)
AST 111122 PDX 111112 SLE 111112 EUG 111112
$$
MORE WEATHER INFORMATION ONLINE AT...
Http://weather.gov/portland
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KOTX 182322 AAA
AFDOTX
AREA FORECAST DISCUSSION...UPDATED AVIATION DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
420 PM PDT THU SEP 18 2008
.SYNOPSIS...
A STRONG RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE INLAND
NORTHWEST...RESULTING IN ANOTHER DAY OF UNSEASONABLY WARM WEATHER
FRIDAY. THE RIDGE WILL BEGIN TO SLOWLY BREAK DOWN BY LATE FRIDAY
NIGHT AND THROUGH THE WEEKEND...AS AN OFFSHORE TROUGH MOVES INLAND.
THIS TROUGH WILL BRING A GRADUAL COOLING TREND...AS WELL AS
INCREASING CHANCES OF PRECIPITATION...THROUGH THE WEEKEND.
&&
.DISCUSSION...
TONIGHT THROUGH SUNDAY...MODELS IN GOOD AGREEMENT THROUGH THE NEXT
12 HOURS. UPPER LEVEL RIDGE CONTINUES TO DOMINATE THE WEATHER FOR
THE NEXT 12-24 HOURS. THE THERMAL TROUGH HASN`T MOVED MUCH OVER THE
LAST 24 HOURS AND WON`T MOVE MUCH OVER THE NEXT 24 HOURS. THIS
TRANSLATES TO CONTINUED MOSTLY CLEAR SKIES...WITH JUST SOME HIGH
CLOUDS MOVING ACROSS. MIDSLOPE TEMPERATURES WILL ONCE AGAIN BE WARM
OVERNIGHT WITH POOR RH RECOVERIES...AND THE PROTECTED VALLEYS ACROSS
THE NORTH WILL BE COOL. THE MAIN FORECAST CHALLENGE TODAY IS JUST
WHAT TO EXPECT THIS WEEKEND. THIS MORNING THE GFS AND ECMWF AGREED
ON THE IDEA OF SWINGING A NEGATIVELY TILTED TROUGH ACROSS US
SATURDAY AND SATURDAY NIGHT RESULTING IN SOME DECENT RAIN FOR MOST
OF EASTERN WA AND NORTH ID. NOW THE 12Z RUNS HAVE FLIPPED BACK TO
THE IDEAS THEY HAD A DAY AND A HALF AGO OF KEEPING THIS CLOSED LOW
TO THE SOUTH...AND TAKING IT ACROSS SOUTHERN OREGON AND NORTHERN
CA/NV. MODELS TYPICALLY HAVE THESE KINDS OF PROBLEMS DURING THE
TRANSITION PERIOD FROM SUMMER TO FALL...AND GIVEN WE ARE GOING FROM
AN UNUSUALLY WARM STATIONARY RIDGE TO A COOL PROGRESSIVE TROUGH-LIKE
SCENARIO I AM NOT SURPRISED BY THE POOR RUN TO RUN CONSISTENCY. THE
12Z CANADIAN IS SIMILAR TO THE 12Z ECMWF AND GFS IN KEEPING THE LOW
TO THE SOUTH...AND HAVE TRIED TO TREND THE FORECAST IN THAT
DIRECTION. WHAT DOES THIS MEAN? WELL THE BEST CHANCE FOR SHOWERS
LOOKS TO BE SATURDAY NIGHT AND SUNDAY ACROSS EXTREME EASTERN WA AND
NORTH ID. GIVEN THE PATH OF THE LOW HAVE ALSO TAKEN OUT ALL MENTION
OF THUNDER. TEMPERATURES GO FROM 10-15 DEGREES ABOVE AVERAGE FRIDAY
TO RIGHT AROUND AVERAGE BY SUNDAY. /NISBET
SUN NIGHT TO MON NIGHT...THE NW REMAINS UNDER A LONG-WAVE TROUGH.
A MODERATE SHORT-WAVE PIVOTS ACROSS THE CWA SUN NIGHT...FOLLOWED
BY A COUPLE WEAKER WAVES LATE MON/MON NIGHT WITH A WNW FLOW. LOOK
FOR A CONTINUE RISK FOR PRECIP OVER THE CASCADES AND ERN THIRD OF
THE CWA. CHANCES WILL BE BEST SUN NIGHT...DWINDLING TO MTN ZONES
MON NIGHT. TUES...HIGH PRESSURE BRIEFLY BUILDS IN. JUST A SLIGHT
CHANCE FOR SHOWERS LINGERS IN THE MTNS. TUE NIGHT TO WED NIGHT...
A WARM FRONT LIFTS THROUGH...BRINGING A RISK FOR SHOWERS TO THE
CASCADES AND MTN ZONES...WHILE INCREASING CLOUDS OVER THE
REMAINDER OF THE CWA. THURSDAY...AN UPPER TROUGH/COLD FRONT PUSHES
TOWARD THE NW. THE 12Z GFS BRINGS IT INTO IDAHO ON THURSDAY. THE 12Z
ECMWF HOLDS IT OVER THE PACIFIC AND KEEPS A RIDGE OVER THE REGION.
GIVEN THE UNCERTAINTY...THERE WILL BE MAINLY A SLIGHT CHANCE FOR
SHOWERS IN THE VALLEYS AND CHANCE POPS IN THE MTNS. TEMPS EXPECTED
TO BE BELOW NORMAL AT THE START OF THE PERIOD...WARMING NEAR AVG BY
WEDNESDAY. THIS IS SUPPORTED BY 850 TEMPS NEAR 5 DEG C AND 1000/500
THICKNESSES NEAR 543-547 DAM MONDAY...MODERATING TOWARD THE LOWER
TEENS AND 560 DAM BY THURSDAY RESPECTIVELY. /JCOTE
&&
.AVIATION...
VFR CONDITIONS EXPECTED AT TAF SITES THROUGH 00Z SATURDAY. A RIDGE
OF HIGH PRESSURE WILL DOMINATE UNTIL LATE FRIDAY...WHEN AN OFFSHORE
TROUGH BEGINS TO MOVE IN. LOOK FOR SOME PASSING MID/HIGH CLOUDS
THROUGH FRIDAY MORNING...WITH CLOUDS STARTING TO INCREASE FROM THE
SW FRIDAY AFTERNOON (INTO SATURDAY). /JCOTE
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 54 87 56 72 49 69 / 0 0 0 30 40 20
COEUR D`ALENE 47 88 52 71 50 67 / 0 0 0 30 50 40
PULLMAN 49 88 51 72 49 69 / 0 0 20 30 30 20
LEWISTON 56 91 61 78 56 74 / 0 10 20 30 30 10
COLVILLE 44 86 42 74 45 71 / 0 0 0 30 50 30
SANDPOINT 41 81 45 70 48 63 / 0 0 0 30 50 50
KELLOGG 50 87 46 68 48 62 / 0 10 10 40 50 50
MOSES LAKE 52 87 57 76 51 76 / 0 0 10 20 10 10
WENATCHEE 57 85 57 75 52 75 / 0 0 10 20 10 10
OMAK 51 89 53 77 47 76 / 0 0 0 20 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
000
FXUS66 KSEW 182211
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 PM PDT THU SEP 18 2008
.SYNOPSIS...MARINE STRATUS WILL CONTINUE TO COVER MOST OF WESTERN
WASHINGTON TONIGHT AND FRIDAY.A WEAK UPPER TROUGH WILL MOVE THROUGH
THE AREA FRIDAY NIGHT AND SATURDAY. AN UNSETTLED WEATHER PATTERN MAY
PERSIST INTO NEXT WEEK.
&&
.SHORT TERM...IT APPEARS THE MARINE STRATUS OVER WESTERN WASHINGTON
IS GOING NOWHERE. HAVE CHANGED FORECAST TO INDICATE MOSTLY CLOUDY
CONDITIONS TONIGHT AND FRIDAY. TEMPS A BIT LOWER TOO.
EURO AND GFS HAVE A FEW SHOWERS FRIDAY AND FRIDAY NIGHT IN THE
MOUNTAINS ASSOCIATED WITH A WEAK SYSTEM MOVING ONSHORE INTO OREGON.
HAVE ADOPTED/KEPT THIS IDEA. SHOWER CHANCE MORE WIDESPREAD SATURDAY
AND SUNDAY AS A WEAK SYSTEM MOVES INTO WASHINGTON. NONE OF THESE
WILL BE BIG QPF EVENTS BUT THERE WILL BE SOME SHOWERS AROUND AND
CHANCE POPS ARE APPROPRIATE. HIGH TEMPS WILL BE CLOSE TO SEASONAL
NORMS...IN THE 60S MAINLY. BURKE
.LONG TERM...SHOWER CHANCE CONTINUES MONDAY OVER CERTAIN AREAS. A
STRONGER SYSTEM ARRIVES TUESDAY THROUGH THURSDAY THOUGH IT LOOKS
LIKE THE FOCUS WILL BE IN BRITISH COLUMBIA. IF THE UPPER RIDGE
BUILDS A LITTLE MORE THEN POPS CAN BE REMOVED FOR THIS PERIOD EXCEPT
FOR THE FAR NORTH. RIGHT NOW MOS POPS ARE IN THE CHANCE CATEGORY AND
IT SEEMS OK TO KEEP POPS IN THE FORECAST. SLOW WARMING TREND IF THE
RIDGE BUILDS. BURKE
&&
.AVIATION...LOWLANDS STILL REMAINED SOCKED THIS AFTERNOON WITH
3000-4000 FT THICK STRATUS LAYER OVER THE AREA. ANY BREAKOUTS LOOK
DOUBTFUL...OR VERY BRIEF AT THIS POINT. DECENT PRES GRADIENT ACROSS
THE CASCADES WITH INCREASING ONSHORE FLOW WILL KEEP LOW CLOUDS OVER
THE AREA...WITH CIGS IN THE MVFR RANGE. CLOSED LOW OVER 40N/130W
WILL MOVE INTO N CA FRI WITH DRY FORECAST CONTINUING FOR W WA. WILL
BE TOUGH TO BREAK OUT OF THE STRATUS ONCE AGAIN FRI AFTERNOON. ANY
SUNBREAKS WILL BE SHORT LIVED. 33
KSEA...LITTLE CHANGE IN THE SKY COVER THIS EVENING WITH MVFR CIGS IN
LOW STRATUS PERSISTING. WINDS WILL STAY LIGHT SOUTHERLY. BRIEF BREAK
IN THE STRATUS POSSIBLE FRI AFTERNOON...ALTHOUGH ALSO EXPECTING
INCREASING MID/HIGH LEVEL CLOUDS OVER THE AREA. 33
&&
.MARINE...ONSHORE FLOW WILL PERSIST OVER W WA TONIGHT WITH HI PRES
ALONG THE COAST AND LOW PRES EAST OF THE CASCADES. EXPECTING A WLY
SURGE THROUGH THE STRAIT THIS EVENING WITH WINDS EASING AFTER
MIDNIGHT. ONSHORE FLOW WILL INCREASE OVER THE WEEKEND AS STRONG 1030
MB HIGH PRES CENTER OVER THE N PAC SHIFTS EAST INTO THE OFFSHORE
WATERS. MAIN EFFECT WILL BE MODERATE WLY WINDS THROUGH THE STRAIT OF
JUAN DE FUCA DURING THE LATE AFTERNOON AND EVENING HOURS. 33
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT OF JUAN DE FUCA.
&&
$$
WEATHER.GOV/SEATTLE
000
FXUS66 KPQR 182137
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
300 PM PDT THU SEP 18 2008
.SYNOPSIS...THICK MARINE CLOUDS HAVE BEGUN TO BREAK APART THIS
AFTERNOON...MOST RAPIDLY DECREASING OVER THE SOUTH PART OF THE
FORECAST AREA. CLOUDS BUT WILL REFORM AND MOVE INLAND AGAIN LATER
TONIGHT. THE NEXT PACIFIC WEATHER SYSTEM WILL MOVE INTO NORTHERN
CALIFORNIA FRIDAY AND WEAKEN WITH ONLY PORTION OF THE TROUGH MOVING
INTO THE FORECAST AREA FRIDAY EVENING. THAT WILL BRING SCATTERED
SHOWERS TO AT LEAST THE MOUNTAINS OF OUR FORECAST AREA. THIS WEATHER
SYSTEM WILL SLOWLY MOVE EAST SATURDAY BUT ANOTHER LOW PRESSURE FROM
THE GULF OF ALASKA WILL SETTLE SOUTH INTO THE FORECAST AREA AND MAY
BRING A FEW SHOWERS TO THE AREA AGAIN LATE THIS WEEKEND AND EARLY
NEXT WEEK BRINGING TEMPERATURES TO AROUND SEASONAL NORMALS.
&&
.SHORT TERM...AFTERNOON SATELLITE VISIBLE IMAGERY LOOPS SHOW THE
THICK CLOUD LAYER OVER THE FORECAST AREA BREAKING APART...MOST
RAPIDLY IN THE SOUTH. CLOUDS WILL MOVE BACK IN AND THICKEN AGAIN
TONIGHT. SATELLITE IMAGERY SHOWS A LOW PRESSURE ARE ALOFT OFF THE
CALIFORNIA COAST CENTERED NEAR 39.5N 132W MOVING SLOWLY TOWARD THE
SOUTHEAST. THIS LOW WILL APPROACH THE NORTHERN CALIFORNIA COAST LATER
TONIGHT...AND WILL MOVE ONSHORE FRIDAY AND WEAKEN WITH AN UPPER
TROUGH PORTION MOVING ACROSS THE FORECAST AREA FRIDAY. THE TRACK
APPEARS A BIT SOUTH OF PREVIOUS MODEL RUNS. THE MAIN FORCING WILL BE
NEAR THE CASCADES AND THE CURRENT FORECAST OF SHOWERS ON THE
CASCADES LOOKS GOOD AND POSSIBLY A LITTLE THUNDER NEAR THE CREST OF
THE LANE COUNTY CASCADES UNDER DIFFLUENT FLOW ALOFT FRI AND FRI
EVENING AS UPPER LEVELS COOL AND LAPSE RATES STEEPEN THERE. STEERING
FLOW COULD BRING SOME CELLS FROM CENTRAL OREGON WHERE LOWER LAYERS
WILL BE WARMER AND ROTATE THEM BACK WEST TO THE CASCADES CREST.
EXPECT A SLIGHT CHANCE OF SHOWERS OVER THE NORTHERN ZONES SATURDAY AS
THE UPPER LEVEL TROUGH MOVES THROUGH THE AREA. WILLSON
.LONG TERM...LONG RANGE MODELS CONTINUE TO SHOW A LOT OF VARIABILITY
IN THE EXTENDED TIME PERIOD. LOOKS LIKE AN UPPER LEVEL TROUGH WILL
MOVE INTO THE FORECAST AREA SUNDAY WITH THE POSSIBILITY OF SOME
SHOWERS AND THE BEST PROSPECTS ON THE NORTH COAST RANGE AND WILLAPA
HILLS. HAVE ADJUSTED GRIDS THERE AND SHOWERS TAPER OFF MONDAY AS THE
UPPER LEVEL TROUGH MOVES OFF TO THE EAST OF THE FORECAST AREA...WITH
A FEW SHOWERS LINGERING OVER THE CASCADES. CONFIDENCE IS LOW FOR THE
REMAINDER OF THE FORECAST AS MODELS TREND TOWARD 180 DEGREES OUT OF
PHASE AT TIMES. WILLSON
&&
.AVIATION...MARINE STRATUS SLOWLY BURNING BACK THIS AFTERNOON WITH
SOUTH WILLAMETTE VALLEY CLEARING FIRST. EXPECT MOST VALLY LOCATIONS
TO CLEAR BY LATER THIS AFTERNOON AND MVFR STRATUS WILL REFORM
OVERNIGHT IN THE SAME AREAS. COAST WILL STAY IN THE MVFR STRATUS
WITH POSSIBLE BRIEF CLEARING ALONG CENTERAL COAST. THE ONSHORE FLOW
WILL WEAKEN SOME OVERNIGHT AND EARLY FRIDAY SO MARINE CLOUDS ARE
EXPECTED TO BURN OFF A LITTLE EARLIER ON FRIDAY. NEXT THING TO
WATCH FOR IS SLIGHT POSSIBILITY OF SOME SHOWERS IN NOTHERN OREGON
CASCADES FRIDAY AFTERNOON AS MOISTURE FROM LOW OFF NORTHERN CA COAST
DRIFTS NORTH.
KPDX AND APPROACHES...MVFR CEILINGS SHOULD BREAK OUT AROUND 22Z-23Z
THEN REFORM AROUND MIDNIGHT. MVFR CLOUDS SHOULD BURN OFF A LITTLE
EARLIER ON FRIDAY THAN TODAY AS ONSHORE GRADIENTS RELAX A LITTLE.
SKT
&&
.MARINE...WEAK HIGH PRES WILL REMAIN ALONG OR JUST OFF THE COAST
THROUGH EARLY FRI. A LOW PRESS 400 NM SW OF CAPE BLANCO WILL WEAKEN
AS IT APPROACHES THE NORTHERN CA COAST FRI...AND SHOULD HAVE LITTLE
IMPACT ON OUR WATERS. ANOTHER WEAK COLD FRONT WILL MOVE THROUGH THE
COASTAL WATERS EARLY SUNDAY. GRADIENTS WILL REMAIN FAIRLY WEAK
THROUGH SAT...THEN PICK UP FROM THE NORTHWEST LATER SUNDAY AS HIGH
PRESS BUILDS IN BEHIND THE FRONT. SEAS WILL REMAIN BELOW 4-6 FEET
THROUGH SUNDAY THEN BEGIN TO INCREASE EARLY NEXT WEEK. EBBS REMAIN
STRONG FOR COLUMBIA RIVER BAR...BUT SEAS REMAIN LIGHT SO NO
ADVISORIES. SKT
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR/WA...NONE.
&&
.PRELIMINARY POINT POPS (PROBABILITY OF MEASURABLE PRECIPITATION)
AST 111122 PDX 111112 SLE 111112 EUG 111112
$$
MORE WEATHER INFORMATION ONLINE AT...
http://weather.gov/portland
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KOTX 182122
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
222 PM PDT THU SEP 18 2008
.SYNOPSIS...
A STRONG RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE INLAND
NORTHWEST RESULTING IN ANOTHER DAY OF UNSEASONABLY WARM WEATHER FRIDAY.
THE RIDGE WILL BEGIN TO SLOWLY BREAK DOWN BY LATE FRIDAY NIGHT AND
THROUGH THE WEEKEND AS AN OFFSHORE TROUGH MOVES INLAND. THIS
TROUGH WILL BRING A GRADUAL COOLING TREND AS WELL AS INCREASING
CHANCES OF PRECIPITATION THROUGH THE WEEKEND.
&&
.DISCUSSION...
TONIGHT THROUGH SUNDAY...MODELS IN GOOD AGREEMENT THROUGH THE NEXT
12 HOURS. AFTER THAT IT IS JUST AN EDUCATED GUESS. UPPER LEVEL
RIDGE CONTINUES TO DOMINATE THE WEATHER FOR THE NEXT 12-24 HOURS.
THE THERMAL TROUGH HASN`T MOVED MUCH OVER THE LAST 24 HOURS AND
WON`T MOVE MUCH OVER THE NEXT 24 HOURS. THIS TRANSLATES TO
CONTINUED MOSTLY CLEAR SKIES...WITH JUST SOME HIGH CLOUDS MOVING
ACROSS. MIDSLOPE TEMPERATURES WILL ONCE AGAIN BE WARM OVERNIGHT
WITH POOR RH RECOVERIES...AND THE PROTECTED VALLEYS ACROSS THE
NORTH WILL BE COOL. THE MAIN FORECAST CHALLENGE TODAY IS JUST WHAT
TO EXPECT THIS WEEKEND?? THIS MORNING THE GFS AND ECMWF AGREED ON
THE IDEA OF SWINGING A NEGATIVELY TILTED TROUGH ACROSS US SATURDAY
AND SATURDAY NIGHT RESULTING IN SOME DECENT RAIN FOR MOST OF
EASTERN WA AND NORTH ID. NOW THE 12Z RUNS HAVE FLIPPED BACK TO THE
IDEAS THEY HAD A DAY AND A HALF AGO OF KEEPING THIS CLOSED LOW TO
THE SOUTH...AND TAKING IT ACROSS SOUTHERN OREGON AND NORTHERN
CA/NV. MODELS TYPICALLY HAVE THESE KINDS OF PROBLEMS DURING THE
TRANSITION PERIOD FROM SUMMER TO FALL...AND GIVEN WE ARE GOING
FROM AN UNUSUALLY WARM STATIONARY RIDGE TO A COOL PROGRESSIVE
TROUGH-LIKE SCENARIO I AM NOT SURPRISED BY THE POOR RUN TO RUN
CONSISTENCY. THE 12Z CANADIAN IS SIMILAR TO THE 12Z ECMWF AND GFS
IN KEEPING THE LOW TO THE SOUTH...AND HAVE TRIED TO TREND THE
FORECAST IN THAT DIRECTION. WHAT DOES THIS MEAN? WELL THE BEST
CHANCE FOR SHOWERS LOOKS TO BE SATURDAY NIGHT AND SUNDAY ACROSS
EXTREME EASTERN WA AND NORTH ID. GIVEN THE PATH OF THE LOW HAVE
ALSO TAKEN OUT ALL MENTION OF THUNDER. TEMPERATURES GO FROM 10-15
DEGREES ABOVE AVERAGE FRIDAY TO RIGHT AROUND AVERAGE BY SUNDAY.
/NISBET
SUN NIGHT TO MON NIGHT...THE NW REMAINS UNDER A LONG-WAVE TROUGH.
A MODERATE SHORT-WAVE PIVOTS ACROSS THE CWA SUN NIGHT...FOLLOWED
BY A COUPLE WEAKER WAVES LATE MON/MON NIGHT WITH A WNW FLOW. LOOK
FOR A CONTINUE RISK FOR PRECIP OVER THE CASCADES AND ERN THIRD OF
THE CWA. CHANCES WILL BE BEST SUN NIGHT...DWINDLING TO MTN ZONES
MON NIGHT. TUES...HIGH PRESSURE BRIEFLY BUILDS IN. JUST A SLIGHT
CHANCE FOR SHOWERS LINGERS IN THE MTNS. TUE NIGHT TO WED NIGHT...
A WARM FRONT LIFTS THROUGH...BRINGING A RISK FOR SHOWERS TO THE
CASCADES AND MTN ZONES...WHILE INCREASING CLOUDS OVER THE
REMAINDER OF THE CWA. THURSDAY...AN UPPER TROUGH/COLD FRONT PUSHES
TOWARD THE NW. THE 12Z GFS BRINGS IT INTO IDAHO. THE 12Z ECMWF
HOLDS IT OVER THE PACIFIC AND KEEPS A RIDGE OVER THE REGION. GIVEN
THE UNCERTAINTY ...THERE WILL BE MAINLY A SLIGHT CHANCE FOR
SHOWERS IN THE VALLEYS AND CHANCE POPS IN THE MTNS. TEMPS EXPECTED
TO BE BELOW NORMAL AT THE START OF THE PERIOD...WARMING NEAR AVG
BY WED. THIS IS SUPPORTED BY 850 TEMPS NEAR 5 DEG C AND 1000/500
THICKNESSES NEAR 543-547 DAM MONDAY...MODERATING TOWARD THE LOWER
TEENS AND 560 DAM BY THURSDAY RESPECTIVELY. /JCOTE
&&
.AVIATION...
VFR WX CAN BE EXPECTED AT ALL TAF SITES THROUGH AT 18Z FRI AS STRONG
UPPER LEVEL RIDGE REMAINS CENTERED OVER EASTERN WA AND NORTH ID.
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 54 87 56 72 49 69 / 0 0 0 30 40 20
COEUR D`ALENE 47 88 52 71 50 67 / 0 0 0 30 50 40
PULLMAN 49 88 51 72 49 69 / 0 0 20 30 30 20
LEWISTON 56 91 61 78 56 74 / 0 10 20 30 30 10
COLVILLE 44 86 42 74 45 71 / 0 0 0 30 50 30
SANDPOINT 41 81 45 70 48 63 / 0 0 0 30 50 50
KELLOGG 50 87 46 68 48 62 / 0 10 10 40 50 50
MOSES LAKE 52 87 57 76 51 76 / 0 0 10 20 10 10
WENATCHEE 57 85 57 75 52 75 / 0 0 10 20 10 10
OMAK 51 89 53 77 47 76 / 0 0 0 20 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
000
FXUS66 KOTX 181728
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1028 AM PDT THU SEP 18 2008
.SYNOPSIS...
A STRONG RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE INLAND
NORTHWEST TODAY RESULTING IN YET ANOTHER DAY OF UNSEASONABLY WARM
WEATHER. THE RIDGE WILL BEGIN TO SLOWLY BREAK DOWN BY LATE FRIDAY
AND THROUGH THE WEEKEND AS AN OFFSHORE TROUGH MOVES INLAND. THIS
TROUGH WILL BRING A GRADUAL COOLING TREND AS WELL AS INCREASING
CHANCES OF PRECIPITATION THROUGH THE WEEKEND.
&&
.DISCUSSION...
TODAY AND TONIGHT...WATER VAPOR LOOPS THIS MORNING SUGGEST NOT
MUCH HAS CHANGED OVER THE INLAND NORTHWEST DURING THE PAST 24
HOURS. THE UPPER LEVEL LOW WHICH WAS LOCATED ALONG 140W YESTERDAY
MORNING HAS SINCE SLID TOWARD 135W WITH A DEEP SOUTHERLY FLOW
AHEAD OF IT. MEANWHILE...UPPER LEVEL RIDGING REMAINS FIRMLY
ENTRENCHED OVER MOST OF THE INLAND NW...AND REALLY SEE NO REASON
FOR THIS TO CHANGE TODAY AS THE LOW IS ONLY EXPECTED TO NEAR 130W
BY LATE AFTERNOON. THE DEEPENING SOUTHERLY FLOW IS EXPECTED TO
BRING A GRADUAL DESTABILIZATION TREND...HOWEVER CLOSE INSPECTION
OF THE DIFFERENTIAL COOLING TRENDS...SUGGESTS THAT NONE OF THE
DESTABILIZATION WILL REALLY IMPACT OUR CWA TODAY. 500 MB TEMP
FALLS AND ASSOCIATED DESTABILIZATION WILL LIKELY REMAIN CONFINED WEST
AND SOUTH OF OUR CWA. IF CONVECTION WERE TO FIRE...BOTH THE NAM
AND GFS SUGGEST THE BEST CHANCES WOULD OCCUR NEAR THE NORTH
CASCADES...HOWEVER MODEL SOUNDING DATA SUGGESTS THE POTENTIAL
INSTABILITY LAYER IS VERY HIGH BASED AND GENERALLY TOO SHALLOW TO
PROVIDE MUCH MORE THAN A FEW ELEVATED ACCAS BUILDUPS. THE OTHER
AREA OF CONCERN TODAY IS OVER THE SE CORNER OF THE CWA...WHERE
ANOTHER ELEVATED LAYER OF POTENTIAL INSTABILITY IS BEING TAPPED
INTO BY A WEAK SHORTWAVE TROF CURRENTLY OVER EAST CENTRAL OREGON.
THIS IS LIKELY THE CAUSE OF THE SCATTERED CLOUDS OVER EASTERN
OREGON AND SE WA. DESPITE THE CLOUDINESS...RADAR RETURNS HAVE
PROVED SCANT SINCE 08Z AND SUSPECT THIS TREND WILL CONTINUE AS THE
AFOREMENTIONED SHORTWAVE CONTINUES TO LIFT NNE AND WEAKEN AS IT
DOES. MODEL SOUNDING DATA ONCE AGAIN SUGGESTS THAT MAIN IMPACT OF
THIS SYSTEM WILL BE SOME CLOUDS...HOWEVER DRY SURFACE DEWPOINTS
AND AN INCREASING STABILITY TREND THROUGH THE DAY WILL GENERALLY
PREVENT ANY CONVECTION FROM FIRING OVER OUR CWA. FOR TONIGHT THE
THREAT OF CONVECTION LOOKS TOO SMALL TO MENTION IN THE GRIDS AS
THE UPPER LEVEL RIDGE REMAINS PARKED OVER THE INLAND NW.
TEMPERATURES TODAY WILL BE SIMILAR TO YESTERDAY AS LOW-LEVEL
THERMAL RIDGE REMAINS CENTERED OVER EASTERN WASHINGTON. LOW-LEVEL
THICKNESS FIELDS ARE ON PAR WITH YESTERDAYS VALUES AND SUGGEST 24
HOUR TEMPERATURE CHANGES WILL BE RATHER INSIGNIFICANT ...EXCEPT
WEST OF THE CASCADE CREST. CONSEQUENTLY WE ARE LOOKING AT YET
ANOTHER DAY WITH HIGH TEMPS RANGING ANYWHERE FROM 10-15 DEGREES
ABOVE NORMALS FOR THIS TIME OF YEAR. MOST OF TODAYS FORECAST HIGHS
WILL COME IN BELOW RECORD LEVELS...HOWEVER READINGS ACROSS THE
NORTHERN TIER OF ZONES FROM OMAK TO COLVILLE AND BONNERS FERRY
WILL COME CLOSE. FX
FRIDAY THROUGH SATURDAY NIGHT...THE RIDGE WILL HOLD ON FOR ONE MORE
DAY OF ABOVE NORMAL TEMPERATURES BEFORE THE UPPER LEVEL
LOW...PRESENTLY CENTERED NEAR 135W...WILL APPROACH THE REGION AND
NUDGE THE RIDGE AXIS TO OUR EAST. AS THE TROUGH STARTS TO SWING
ASHORE SOME MID LEVEL MOISTURE WILL MOVE IN FROM THE SOUTH RIDING
ALONG THE WEST SIDE OF THE RIDGE. WHILE IT MAY TAKE A WHILE TO
MOISTEN THE LOWER LEVELS THERE SHOULD BE ENOUGH POTENTIAL
INSTABILITY FOR ISOLATED THUNDERSTORMS TO DEVELOP ACROSS THE
SOUTHEAST CORNER OF THE FORECAST AREA FRIDAY AFTERNOON AND EVENING.
MODELS CONTINUE THE TREND OF SHIFTING THE TRACK OF THE SHORTWAVE
THROUGH FARTHER NORTH WITH THE BULK OF THE ENERGY IMPACTING THE
INLAND NORTHWEST RATHER THAN SLIDING TO OUR SOUTH. POPS HAVE BEEN
INCREASED ACROSS THE FORECAST AREA FOR SATURDAY AS THE NEGATIVELY
TILTED TROUGH MOVES THROUGH THE REGION. TEMPERATURES WILL BE QUITE A
BIT COOLER WITH MOST VALLEY LOCATIONS IN THE 70S.
SUNDAY THROUGH WEDNESDAY...COOL AND UNSETTLED CONDITIONS WILL
PREVAIL ACROSS THE REGION THROUGH THE EXTENDED FORECAST PERIOD AS
THE TROUGHY PATTERN CONTINUES. POPS REMAIN CLOSE TO CLIMO WITH
TEMPERATURES REMAINING BELOW SEASONAL NORMALS. /KELCH
&&
.AVIATION...
VFR WX CAN BE EXPECTED AT ALL TAF SITES THROUGH AT 18Z FRI AS STRONG
UPPER LEVEL RIDGE REMAINS CENTERED OVER EASTERN WA AND NORTH ID.
LOCALIZED GUSTY WINDS WILL CONTINUE ACROSS THE WENATCHEE VALLEY
THROUGH THE EVENING.
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 89 52 85 55 72 48 / 0 0 10 10 20 30
COEUR D`ALENE 87 48 86 53 71 48 / 0 0 10 10 20 30
PULLMAN 88 50 86 53 71 49 / 0 0 10 10 20 30
LEWISTON 91 58 88 61 77 54 / 0 0 10 10 20 20
COLVILLE 89 45 85 48 74 44 / 0 0 0 0 20 30
SANDPOINT 82 41 80 49 70 46 / 0 0 10 10 30 30
KELLOGG 89 52 86 51 68 46 / 0 0 10 10 40 40
MOSES LAKE 92 53 87 56 76 49 / 0 0 10 10 20 10
WENATCHEE 88 57 85 55 75 51 / 0 0 10 10 20 10
OMAK 91 51 88 53 76 47 / 0 0 0 10 20 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
000
FXUS66 KPQR 181557
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
900 AM PDT THU SEP 18 2008
.SYNOPSIS...MARINE CLOUDS HAVE INUNDATED THE FORECAST AREA THIS
MORNING PUSHING WILL UP INTO THE CASCADE VALLEYS. THE LAYER IS ABOUT
2000 FEET THICK AND WILL BE SLOW TO CLEAR TODAY. THE NEXT PACIFIC
WEATHER SYSTEM WILL MOVE INTO SOUTHERN OREGON AND NORTHERN CALIFORNIA
FRIDAY AND NORTHEAST INTO THE FORECAST AREA FRIDAY EVENING AND WILL
BRING SCATTERED SHOWERS TO AT LEAST THE MOUNTAINS OF OUR FORECAST
AREA. THIS WEATHER SYSTEM WILL SLOWLY MOVE EAST SATURDAY BUT ANOTHER
LOW PRESSURE FROM THE GULF OF ALASKA WILL SETTLE SOUTH INTO THE
FORECAST AREA AND MAY BRING A FEW SHOWERS TO THE AREA AGAIN LATE THIS
WEEKEND AND EARLY NEXT WEEK BRINGING TEMPERATURES TO AROUND SEASONAL
NORMALS.
&&
.SHORT TERM...THE SALEM UPPER AIR SOUNDING THIS MORNING SHOWED THE
TOP OF THE MARINE LAYER THAT INUNDATED THE FORECAST AREA AT AROUND
4500 FEET WITH MVFR BASES REPORTED ON OBSERVATIONS. THE MORNING
VISUAL SATELLITE IMAGERY SHOWS DENDRITIC PATTERNS WHERE THE MARINE
CLOUDS HAVE PUSHED WELL UP INTO THE CASCADE VALLEYS SO IT WILL BE A
VERY SLOW CLEAR OUT TODAY AND MAY HAVE A HARD TIME CLIMBING UP ACROSS
THE 70 DEGREE MARK THIS AFTERNOON. SATELLITE IMAGERY SHOWS THE NEXT
UPSTREAM SYSTEM OFF THE CALIFORNIA COAST CENTERED NEAR 40N 134W
MOVING SLOWLY SOUTHEAST. THIS LOW WILL APPROACHES THE SOUTHERN OREGON
AND NORTHERN CALIFORNIA COASTS LATER TODAY...AND WILL MOVE ONSHORE
LATE THURSDAY NIGHT AND FRIDAY AND INTO THE FORECAST AREA FRIDAY
NIGHT AND SATURDAY WEAKENING TO A DIFFLUENT NEGATIVE TILT UPPER LEVEL
TROUGH. THE MAIN FORCING WILL BE NEAR THE CASCADES AND THE CURRENT
FORECAST OF SHOWERS ON THE CASCADES LOOKS GOOD AND POSSIBLY A LITTLE
THUNDER NEAR THE CREST ON FRI AND FRI EVENING AS UPPER LEVELS COOL
AND LAPSE RATES STEEPEN THERE. STEERING FLOW COULD BRING SOME CELLS
FROM CENTRAL OREGON WHERE LOWER LAYERS WILL BE WARMER AND ROTATE THEM
BACK WEST TO THE CASCADES CREST. EXPECT A SLIGHT CHANCE OF SHOWERS
OVER THE NORTHERN ZONES SATURDAY AS THE UPPER LEVEL TROUGH MOVES
THROUGH THE AREA. WILLSON
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
LONG RANGE MODELS ARE SHOWING MORE VARIABILITY IN THE
EXTENDED TIME PERIOD. SHOWERS TAPER OFF SUNDAY AS THE UPPER LEVEL
TROUGH MOVES EAST OF THE FORECAST AREA...WITH A FEW SHOWERS OVER THE
CASCADES MONDAY. CONFIDENCE IS LOW FOR THE REMAINDER OF THE FORECAST.
MODELS VARY GREATLY IN THEIR SOLUTIONS...SO WILL KEEP TUE AND WED DRY
FOR NOW...UNTIL MODELS AGREE ON A SOLUTION.
&&
.AVIATION...SOLID MVFR STRATUS DECK WITH MVFR CEILINGS WILL COVER
AREAS W OF THE CASCADES THIS MORNING. INLAND AREAS WILL STRUGGLE TO
BREAK OUT DURING THE AFTERNOON AS STRATUS MODERATE ONSHORE FLOW
CONTINUES AND CURRENT CLOUD LAYER IS ABOUT 2K FT THICK WITH TOPS
JUST OVER 4K FT. MIGHT SEE SOME LIFTING OF CLOUD DECK AFTER 18Z AND
PARTIAL CLEARING AFTER ABOUT 21Z. COASTAL TERMINALS WILL LIKELY
REMAIN MVFR TODAY.
KPDX AND APPROACHES...MVFR CEILINGS AROUND 2000 FT THIS MORNING BUT
SHOULD REMAIN ABOVE IFR. CLOUDS ARE EXPECTED TO SLOWLY LIFT AND
BREAK UP DURING THE LATE AFTERNOON WITH VFR RETURNING TO THE KPDX
AREA AFTER NOON. SKT
&&
.MARINE...WEAK HIGH PRES WILL REMAIN IN THE VICINITY OF THE COASTAL
WATERS THROUGH EARLY FRI. LOW PRESS 500 NM W OF CAPE BLANCO WILL
WEAKEN AS IT APPROACHES THE NORTHERN CA/SOUTHERN OREGON COAST
FRI...AND SHOULD HAVE LITTLE IMPACT ON OUR WATERS. AN ASSOCIATED
WEAK COLD FRONT WILL MOVE THROUGH THE AREA FRI NIGHT OR SAT.
GRADIENTS WILL REMAIN FAIRLY WEAK THROUGH SAT...SO EXPECT MAINLY
LIGHT WINDS/SEAS FOR THE NEXT 2-3 DAYS. HIGH PRES BUILDING IN BEHIND
THE FRONT MAY CAUSE STRONGER N-NW WINDS TO DEVELOP BY SUN/MON. EBBS
REMAIN STRONG FOR COLUMBIA RIVER BAR...BUT SEAS REMAIN LIGHT SO NO
ADVISORIES. SKT
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR/WA...NONE.
&&
.PRELIMINARY POINT POPS (PROBABILITY OF MEASURABLE PRECIPITATION)
AST 11111 PDX 1111- SLE 1111- EUG 1111-
$$
MORE WEATHER INFORMATION ONLINE AT...
Http://weather.gov/portland
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KSEW 181546
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
830 AM PDT THU SEP 18 2008
.SYNOPSIS...LOW LEVEL ONSHORE FLOW BROUGHT MARINE STRATUS INTO
WESTERN WASHINGTON EARLY THIS MORNING. THE CLOUDS WILL BURN BACK
TOWARD THE COAST THIS AFTERNOON THEN MOVE INLAND AGAIN OVERNIGHT
THROUGH FRIDAY MORNING. A WEAK UPPER TROUGH WILL MOVE THROUGH THE
AREA FRIDAY NIGHT AND SATURDAY. AN UNSETTLED WEATHER PATTERN MAY
PERSIST INTO NEXT WEEK.
&&
.SHORT TERM...STRATUS COVERS MOST OF WESTERN WASHINGTON AND EXTENDS
UP THE CASCADE VALLEYS. HOWEVER THE CASCADE MOUNTAINS ARE BASICALLY
IN THE CLEAR. OLYMPICS WOULD BE CLEAR TOO EXCEPT THERE IS A FAIR BIT
OF CIRRUS OVERHEAD. PRESSURE GRADIENTS HAVE TURNED SLIGHTLY OFFSHORE
SO THE STRATUS HAS PROBABLY PENETRATED AS FAR AS IT WILL GO TODAY.
EXPECT CLEARING LATE THIS AFTERNOON...EARLY THIS EVENING FOR SOME
WESTERN AREAS. TEMPS WILL BE DOWN ABOUT 5 DEGREES FROM YESTERDAY.
PATTERN WILL BE SIMILAR FRIDAY WITH MORNING CLOUDS AND AFTERNOON
SUN. THE WEEKEND WILL NOT ONLY HAVE MARINE STRATUS...BUT ALSO SOME
HIGHER CLOUDS ASSOCIATED WITH AN UPPER LEVEL TROUGH SWINGING THROUGH
THE AREA. HIGH TEMPS WILL BE IN THE 60S. BOTH THE GFS AND NAM HAVE
CHANCE POPS FRIDAY NIGHT THROUGH SUNDAY. THIS IS NOT A BIG STORM BY
ANY MEANS BUT SCATTERED LIGHT SHOWERS ARE DEFINITELY A POSSIBILITY
AND THEY ARE IN THE FORECAST. BURKE
.LONG TERM...PREVIOUS DISCUSSION...NO CHANGE TO EXTENDED FORECAST
THIS SHIFT AND FORECAST IS CLOSE TO CLIMO WHICH IS OKAY AT THIS TIME
RANGE. IF THE MODELS HOLD TO THE 00Z SOLUTION HOWEVER THEN HIGHER
POPS MIGHT BE COMING FOR SUNDAY AND AGAIN BY WED. GFS HAS UPPER TROF
SUN WITH SHOWERS...AGAIN THE WRF EXTENSION LOOKS WET W/ A HALF AN
INCH OR MORE IN THE CASCADES AND FOOTHILLS AND NORTH INTERIOR. THE
GFS HAS ANOTHER TROF HANGING BACK IN THE NE PAC WHILE THE ECMWF
SHOWS A MORE CONSOLIDATED UPPER TROF MOVING THRU THE REGION ON
MONDAY. THEN BOTH MODELS SHOW A DIRTY RIDGE JUST OFFSHORE W/ 500MB
IN 570S. THE 00Z GFS HAS A SOAKING RAIN EVENT IN THE MOUNTAINS BY
WED. WRF EXTENSION SHOWS 1-2.5" IN THE MTNS IN 24HRS BUT LESS THAN A
QUARTER INCH LOWLANDS. FORECAST MAY HAVE SOME CATCHING UP TO DO IF
THE GFS PERSISTS WITH THIS IDEA. THE ECMWF IS SLOWER AND TAKES MORE
OF THE MOISTURE INTO B.C. BEFORE BRINGING RAIN INTO WRN WA THU. THAT
ADDRESSES THE WETTER POSSIBILITY. BUT IT IS ALSO A GOOD GUESS AT
THIS TIME RANGE THAT THE MODELS WILL NOW AMPLIFY THE FLOW A BIT MORE
AND THAT COULD KEEP SYSTEMS GOING TO THE NORTH OF WA. AS I SAID FOR
NOW FORECAST LOOKS FINE WITH SOME CLOUDS AND TEMPS IN THE 60S. 19
&&
.AVIATION...LOWLANDS REMAINED SOCKED IN THIS MORNING AS MARINE LAYER
MOVED IN OVERNIGHT. STRONG LOW LEVEL INVERSION KEEPING CIGS QUITE
LOW WITH IFR TO LIFR CONDITIONS REPORTED ACROSS THE INTERIOR.
ESTIMATED THICKNESS OF THE STRATUS LAYER IS 3000FT OVR PUGET SOUND
...BASED ON RECENT PILOT REPORTS AND ACARS SOUNDINGS. CEILING OVER
THE INTERIOR WILL GRADUALLY LIFT WITH BKN020-030 SKIES THIS
AFTERNOON 20-22Z...THEN SCT CLOUDS DURING THE LATE AFTERNOON AND
EARLY EVENING. THE COAST HOWEVER SHOULD REMAIN CLOUDY AND MVFR. LOW
CLOUDS WILL FILL BACK IN OVERNIGHT AS ONSHORE FLOW INCREASES. 33
KSEA...IFR CONDITIONS WILL CONTINUE THROUGH THE MORNING WITH LOWER
VIS AT TIMES IN BR. CIGS WILL GRADUALLY LIFT TODAY WITH A BREAKOUT
EXPECTED LATE AFTERNOON AND EARLY EVENING. STRATUS WILL FILL BACK IN
OVERNIGHT HOWEVER CIGS WILL BE HIGHER...BUT STILL IN THE MVFR RANGE.
WINDS TODAY EXPECTED TO REMAIN SOUTHERLY. 33
&&
.MARINE...ONSHORE FLOW ACROSS W WA WILL CONTINUE TODAY WITH HI PRES
ALONG THE COAST AND LOWER PRES E OF THE CASCADES. STRONGEST WINDS
WILL BE FOUND THROUGH THE STRAIT OF JUAN DE FUCA WITH WLY WINDS
RISING TO 15 TO 25 KT THIS AFTERNOON. ONSHORE FLOW PATTERN WILL
PERSIST OVER THE NEXT SEVERAL DAYS. 33
&&
.FIRE WEATHER...THE COOL...HUMID AND STABLE INFLUENCE OF THE MARINE
LAYER EXTENDS UP TO ABOUT 3500 TO 4000 FEET THIS MORNING. CONDITIONS
ARE STILL DRY ABOVE THAT...BUT THE KUIL AND KSLE SOUNDINGS FROM 12Z
BOTH SHOWED MID-LEVEL HAINES INDEX OF 4. EVEN ABOVE THE MARINE
LAYER...THE AIR MASS SHOULD CONTINUE TO SLOWLY STABILIZE TODAY. AS A
RESULT...THE RED FLAG WARNING WAS CANCELLED AROUND 730 AM THIS
MORNING. HANER
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT OF JUAN DE FUCA.
&&
$$
WEATHER.GOV/SEATTLE
000
FXUS66 KOTX 181222
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
516 AM PDT THU SEP 18 2008
.SYNOPSIS...
A STRONG RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE INLAND
NORTHWEST TODAY RESULTING IN YET ANOTHER DAY OF UNSEASONABLY WARM
WEATHER. THE RIDGE WILL BEGIN TO SLOWLY BREAK DOWN BY LATE FRIDAY
AND THROUGH THE WEEKEND AS AN OFFSHORE TROUGH MOVES INLAND. THIS
TROUGH WILL BRING A GRADUAL COOLING TREND AS WELL AS INCREASING
CHANCES OF PRECIPITATION THROUGH THE WEEKEND.
&&
.DISCUSSION...
TODAY AND TONIGHT...WATER VAPOR LOOPS THIS MORNING SUGGEST NOT
MUCH HAS CHANGED OVER THE INLAND NORTHWEST DURING THE PAST 24
HOURS. THE UPPER LEVEL LOW WHICH WAS LOCATED ALONG 140W YESTERDAY
MORNING HAS SINCE SLID TOWARD 135W WITH A DEEP SOUTHERLY FLOW
AHEAD OF IT. MEANWHILE...UPPER LEVEL RIDGING REMAINS FIRMLY
ENTRENCHED OVER MOST OF THE INLAND NW...AND REALLY SEE NO REASON
FOR THIS TO CHANGE TODAY AS THE LOW IS ONLY EXPECTED TO NEAR 130W
BY LATE AFTERNOON. THE DEEPENING SOUTHERLY FLOW IS EXPECTED TO
BRING A GRADUAL DESTABILIZATION TREND...HOWEVER CLOSE INSPECTION
OF THE DIFFERENTIAL COOLING TRENDS...SUGGESTS THAT NONE OF THE
DESTABILIZATION WILL REALLY IMPACT OUR CWA TODAY. 500 MB TEMP
FALLS AND ASSOCIATED DESTABILIZATION WILL LIKELY REMAIN CONFINED WEST
AND SOUTH OF OUR CWA. IF CONVECTION WERE TO FIRE...BOTH THE NAM
AND GFS SUGGEST THE BEST CHANCES WOULD OCCUR NEAR THE NORTH
CASCADES...HOWEVER MODEL SOUNDING DATA SUGGESTS THE POTENTIAL
INSTABILITY LAYER IS VERY HIGH BASED AND GENERALLY TOO SHALLOW TO
PROVIDE MUCH MORE THAN A FEW ELEVATED ACCAS BUILDUPS. THE OTHER
AREA OF CONCERN TODAY IS OVER THE SE CORNER OF THE CWA...WHERE
ANOTHER ELEVATED LAYER OF POTENTIAL INSTABILITY IS BEING TAPPED
INTO BY A WEAK SHORTWAVE TROF CURRENTLY OVER EAST CENTRAL OREGON.
THIS IS LIKELY THE CAUSE OF THE SCATTERED CLOUDS OVER EASTERN
OREGON AND SE WA. DESPITE THE CLOUDINESS...RADAR RETURNS HAVE
PROVED SCANT SINCE 08Z AND SUSPECT THIS TREND WILL CONTINUE AS THE
AFOREMENTIONED SHORTWAVE CONTINUES TO LIFT NNE AND WEAKEN AS IT
DOES. MODEL SOUNDING DATA ONCE AGAIN SUGGESTS THAT MAIN IMPACT OF
THIS SYSTEM WILL BE SOME CLOUDS...HOWEVER DRY SURFACE DEWPOINTS
AND AN INCREASING STABILITY TREND THROUGH THE DAY WILL GENERALLY
PREVENT ANY CONVECTION FROM FIRING OVER OUR CWA. FOR TONIGHT THE
THREAT OF CONVECTION LOOKS TOO SMALL TO MENTION IN THE GRIDS AS
THE UPPER LEVEL RIDGE REMAINS PARKED OVER THE INLAND NW.
TEMPERATURES TODAY WILL BE SIMILAR TO YESTERDAY AS LOW-LEVEL
THERMAL RIDGE REMAINS CENTERED OVER EASTERN WASHINGTON. LOW-LEVEL
THICKNESS FIELDS ARE ON PAR WITH YESTERDAYS VALUES AND SUGGEST 24
HOUR TEMPERATURE CHANGES WILL BE RATHER INSIGNIFICANT ...EXCEPT
WEST OF THE CASCADE CREST. CONSEQUENTLY WE ARE LOOKING AT YET
ANOTHER DAY WITH HIGH TEMPS RANGING ANYWHERE FROM 10-15 DEGREES
ABOVE NORMALS FOR THIS TIME OF YEAR. MOST OF TODAYS FORECAST HIGHS
WILL COME IN BELOW RECORD LEVELS...HOWEVER READINGS ACROSS THE
NORTHERN TIER OF ZONES FROM OMAK TO COLVILLE AND BONNERS FERRY
WILL COME CLOSE. FX
FRIDAY THROUGH SATURDAY NIGHT...THE RIDGE WILL HOLD ON FOR ONE MORE
DAY OF ABOVE NORMAL TEMPERATURES BEFORE THE UPPER LEVEL
LOW...PRESENTLY CENTERED NEAR 135W...WILL APPROACH THE REGION AND
NUDGE THE RIDGE AXIS TO OUR EAST. AS THE TROUGH STARTS TO SWING
ASHORE SOME MID LEVEL MOISTURE WILL MOVE IN FROM THE SOUTH RIDING
ALONG THE WEST SIDE OF THE RIDGE. WHILE IT MAY TAKE A WHILE TO
MOISTEN THE LOWER LEVELS THERE SHOULD BE ENOUGH POTENTIAL
INSTABILITY FOR ISOLATED THUNDERSTORMS TO DEVELOP ACROSS THE
SOUTHEAST CORNER OF THE FORECAST AREA FRIDAY AFTERNOON AND EVENING.
MODELS CONTINUE THE TREND OF SHIFTING THE TRACK OF THE SHORTWAVE
THROUGH FARTHER NORTH WITH THE BULK OF THE ENERGY IMPACTING THE
INLAND NORTHWEST RATHER THAN SLIDING TO OUR SOUTH. POPS HAVE BEEN
INCREASED ACROSS THE FORECAST AREA FOR SATURDAY AS THE NEGATIVELY
TILTED TROUGH MOVES THROUGH THE REGION. TEMPERATURES WILL BE QUITE A
BIT COOLER WITH MOST VALLEY LOCATIONS IN THE 70S.
SUNDAY THROUGH WEDNESDAY...COOL AND UNSETTLED CONDITIONS WILL
PREVAIL ACROSS THE REGION THROUGH THE EXTENDED FORECAST PERIOD AS
THE TROUGHY PATTERN CONTINUES. POPS REMAIN CLOSE TO CLIMO WITH
TEMPERATURES REMAINING BELOW SEASONAL NORMALS. /KELCH
&&
.AVIATION...
VFR WX CAN BE EXPECTED AT ALL TAF SITES THROUGH AT 12Z FRI AS STRONG
UPPER LEVEL RIDGE REMAINS CENTERED OVER EASTERN WA AND NORTH ID. FX
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 89 52 85 55 72 48 / 0 0 10 10 20 30
COEUR D`ALENE 87 48 86 53 71 48 / 0 0 10 10 20 30
PULLMAN 88 50 86 53 71 49 / 0 0 10 10 20 30
LEWISTON 91 58 88 61 77 54 / 0 0 10 10 20 20
COLVILLE 89 45 85 48 74 44 / 0 0 0 0 20 30
SANDPOINT 82 41 80 49 70 46 / 0 0 10 10 30 30
KELLOGG 89 52 86 51 68 46 / 0 0 10 10 40 40
MOSES LAKE 92 53 87 56 76 49 / 0 0 10 10 20 10
WENATCHEE 88 57 85 55 75 51 / 0 0 10 10 20 10
OMAK 91 51 88 53 76 47 / 0 0 0 10 20 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
000
FXUS66 KOTX 181016
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
316 AM PDT THU SEP 18 2008
.SYNOPSIS...
A STRONG RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE INLAND
NORTHWEST TODAY RESULTING IN YET ANOTHER DAY OF UNSEASONABLY WARM
WEATHER. THE RIDGE WILL BEGIN TO SLOWLY BREAK DOWN BY LATE FRIDAY
AND THROUGH THE WEEKEND AS AN OFFSHORE TROUGH MOVES INLAND. THIS
TROUGH WILL BRING A GRADUAL COOLING TREND AS WELL AS INCREASING
CHANCES OF PRECIPITATION THROUGH THE WEEKEND.
&&
.DISCUSSION...
TODAY AND TONIGHT...WATER VAPOR LOOPS THIS MORNING SUGGEST NOT
MUCH HAS CHANGED OVER THE INLAND NORTHWEST DURING THE PAST 24
HOURS. THE UPPER LEVEL LOW WHICH WAS LOCATED ALONG 140W YESTERDAY
MORNING HAS SINCE SLID TOWARD 135W WITH A DEEP SOUTHERLY FLOW
AHEAD OF IT. MEANWHILE...UPPER LEVEL RIDGING REMAINS FIRMLY
ENTRENCHED OVER MOST OF THE INLAND NW...AND REALLY SEE NO REASON
FOR THIS TO CHANGE TODAY AS THE LOW IS ONLY EXPECTED TO NEAR 130W
BY LATE AFTERNOON. THE DEEPENING SOUTHERLY FLOW IS EXPECTED TO
BRING A GRADUAL DESTABILIZATION TREND...HOWEVER CLOSE INSPECTION
OF THE DIFFERENTIAL COOLING TRENDS...SUGGESTS THAT NONE OF THE
DESTABILIZATION WILL REALLY IMPACT OUR CWA TODAY. 500 MB TEMP
FALLS AND ASSOCIATED DESTABILIZATION WILL LIKELY REMAIN CONFINED WEST
AND SOUTH OF OUR CWA. IF CONVECTION WERE TO FIRE...BOTH THE NAM
AND GFS SUGGEST THE BEST CHANCES WOULD OCCUR NEAR THE NORTH
CASCADES...HOWEVER MODEL SOUNDING DATA SUGGESTS THE POTENTIAL
INSTABILITY LAYER IS VERY HIGH BASED AND GENERALLY TOO SHALLOW TO
PROVIDE MUCH MORE THAN A FEW ELEVATED ACCAS BUILDUPS. THE OTHER
AREA OF CONCERN TODAY IS OVER THE SE CORNER OF THE CWA...WHERE
ANOTHER ELEVATED LAYER OF POTENTIAL INSTABILITY IS BEING TAPPED
INTO BY A WEAK SHORTWAVE TROF CURRENTLY OVER EAST CENTRAL OREGON.
THIS IS LIKELY THE CAUSE OF THE SCATTERED CLOUDS OVER EASTERN
OREGON AND SE WA. DESPITE THE CLOUDINESS...RADAR RETURNS HAVE
PROVED SCANT SINCE 08Z AND SUSPECT THIS TREND WILL CONTINUE AS THE
AFOREMENTIONED SHORTWAVE CONTINUES TO LIFT NNE AND WEAKEN AS IT
DOES. MODEL SOUNDING DATA ONCE AGAIN SUGGESTS THAT MAIN IMPACT OF
THIS SYSTEM WILL BE SOME CLOUDS...HOWEVER DRY SURFACE DEWPOINTS
AND AN INCREASING STABILITY TREND THROUGH THE DAY WILL GENERALLY
PREVENT ANY CONVECTION FROM FIRING OVER OUR CWA. FOR TONIGHT THE
THREAT OF CONVECTION LOOKS TOO SMALL TO MENTION IN THE GRIDS AS
THE UPPER LEVEL RIDGE REMAINS PARKED OVER THE INLAND NW.
TEMPERATURES TODAY WILL BE SIMILAR TO YESTERDAY AS LOW-LEVEL
THERMAL RIDGE REMAINS CENTERED OVER EASTERN WASHINGTON. LOW-LEVEL
THICKNESS FIELDS ARE ON PAR WITH YESTERDAYS VALUES AND SUGGEST 24
HOUR TEMPERATURE CHANGES WILL BE RATHER INSIGNIFICANT ...EXCEPT
WEST OF THE CASCADE CREST. CONSEQUENTLY WE ARE LOOKING AT YET
ANOTHER DAY WITH HIGH TEMPS RANGING ANYWHERE FROM 10-15 DEGREES
ABOVE NORMALS FOR THIS TIME OF YEAR. MOST OF TODAYS FORECAST HIGHS
WILL COME IN BELOW RECORD LEVELS...HOWEVER READINGS ACROSS THE
NORTHERN TIER OF ZONES FROM OMAK TO COLVILLE AND BONNERS FERRY
WILL COME CLOSE. FX
FRIDAY THROUGH SATURDAY NIGHT...THE RIDGE WILL HOLD ON FOR ONE MORE
DAY OF ABOVE NORMAL TEMPERATURES BEFORE THE UPPER LEVEL
LOW...PRESENTLY CENTERED NEAR 135W...WILL APPROACH THE REGION AND
NUDGE THE RIDGE AXIS TO OUR EAST. AS THE TROUGH STARTS TO SWING
ASHORE SOME MID LEVEL MOISTURE WILL MOVE IN FROM THE SOUTH RIDING
ALONG THE WEST SIDE OF THE RIDGE. WHILE IT MAY TAKE A WHILE TO
MOISTEN THE LOWER LEVELS THERE SHOULD BE ENOUGH POTENTIAL
INSTABILITY FOR ISOLATED THUNDERSTORMS TO DEVELOP ACROSS THE
SOUTHEAST CORNER OF THE FORECAST AREA FRIDAY AFTERNOON AND EVENING.
MODELS CONTINUE THE TREND OF SHIFTING THE TRACK OF THE SHORTWAVE
THROUGH FARTHER NORTH WITH THE BULK OF THE ENERGY IMPACTING THE
INLAND NORTHWEST RATHER THAN SLIDING TO OUR SOUTH. POPS HAVE BEEN
INCREASED ACROSS THE FORECAST AREA FOR SATURDAY AS THE NEGATIVELY
TILTED TROUGH MOVES THROUGH THE REGION. TEMPERATURES WILL BE QUITE A
BIT COOLER WITH MOST VALLEY LOCATIONS IN THE 70S.
SUNDAY THROUGH WEDNESDAY...COOL AND UNSETTLED CONDITIONS WILL
PREVAIL ACROSS THE REGION THROUGH THE EXTENDED FORECAST PERIOD AS
THE TROUGHY PATTERN CONTINUES. POPS REMAIN CLOSE TO CLIMO WITH
TEMPERATURES REMAINING BELOW SEASONAL NORMALS. /KELCH
&&
.AVIATION...
VFR WX CAN BE EXPECTED AT ALL TAF SITES THROUGH AT LEAST 06Z FRI. THE
ONLY NOTE OF INTEREST WILL BE AN INCREASE OF MID AND HI CLOUDS
MOVING N OUT OF OREGON AND INTO SERN WA. CEILINGS SHOULD NOT BE
ANY LOWER THAN 11-13K FT AGL FOR THE KLWS AN KPUW TAFS OVERNIGHT.
BZ
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 89 52 85 55 72 48 / 0 0 10 10 20 30
COEUR D`ALENE 87 48 86 53 71 48 / 0 0 10 10 20 30
PULLMAN 88 50 86 53 71 49 / 0 0 10 10 20 30
LEWISTON 91 58 88 61 77 54 / 0 0 10 10 20 20
COLVILLE 89 45 85 48 74 44 / 0 0 0 0 20 30
SANDPOINT 82 41 80 49 70 46 / 0 0 10 10 30 30
KELLOGG 89 52 86 51 68 46 / 0 0 10 10 40 40
MOSES LAKE 92 53 87 56 76 49 / 0 0 10 10 20 10
WENATCHEE 88 57 85 55 75 51 / 0 0 10 10 20 10
OMAK 91 51 88 53 76 47 / 0 0 0 10 20 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
000
FXUS66 KPQR 180958
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
254 AM PDT THU SEP 18 2008
.SYNOPSIS...ONSHORE FLOW USHERING MARINE CLOUDS WELL INLAND ACROSS
NORTHWEST OREGON AND SOUTHWEST WASHINGTON. THE NEXT PACIFIC WEATHER
SYSTEM NOW LOOKS AS THOUGH IT WILL MOVE INTO SOUTHERN OREGON AND
NORTHERN CALIFORNIA FRIDAY AND BRING SOME SCATTERED SHOWERS TO AT
LEAST THE MOUNTAINS OF OUR AREA. THIS SYSTEM WILL SLOWLY MOVE EAST
THROUGH SATURDAY...BUT ADDITIONAL LOW PRESSURE SYSTEMS MAY BRING A
FEW SHOWERS TO THE AREA AGAIN LATE THIS WEEKEND AND EARLY NEXT WEEK
BRINGING TEMPERATURES TO AROUND SEASONAL NORMALS.
&&
.SHORT TERM...MARINE CLOUDS HAVE PUSHED INLAND AND HAS ALMOST
COMPLETELY COVERED THE WILLAMETTE VALLEY AND THE LOWLANDS IN
SOUTHWEST WASHINGTON EARLY THIS MORNING. THE CLOUDS WILL ALSO PUSH
INTO THE LOWER CASCADES THIS MORNING. THIS WILL BRING ABOUT 6 TO 10
DEGREES COOLING OVER WED FOR INLAND AREAS BUT NOT TOO MUCH CHANGE FOR
THE COAST.
SATELLITE IMAGERY SHOWS THE NEXT UPSTREAM SYSTEM SPINNING OFF THE
CALIFORNIA COAST CENTERED AT 40N 135W. IT IS MOVING SLOWLY EAST AT
THIS TIME. THIS LOW APPROACHES THE SOUTHERN OREGON AND NORTHERN
CALIFORNIA COASTS LATER TODAY...AND WILL MOVE ONSHORE LATE THURSDAY
NIGHT AND FRIDAY. THE ONSHORE FLOW PERSISTS WITH A DEEP ENOUGH MARINE
LAYER SO SHOULD HAVE NIGHT AND MORNING CLOUDS WEST OF THE CASCADES.
NAM AND GFS MODELS MORE SIMILAR NOW WITH THE LOW SWINGING NE OVER THE
AREA FRI NIGHT AND SAT WHILE WEAKENING AS IT PUSHES INLAND. FOR NOW
CURRENT FORECAST OF SHOWERS ON THE CASCADES AND POSSIBLY A LITTLE
THUNDER NEAR THE CREST ON FRI AND FRI EVENING LOOK GOOD. STEERING
FLOW COULD BRING SOME CELLS FROM CENTRAL OREGON AND ROTATE BACK WEST
THE CASCADES CREST. EXPECT A SLIGHT CHANCE OF SHOWERS OVER THE
NORTHERN ZONES SATURDAY AS THE UPPER LEVEL TROUGH MOVES THROUGH THE
AREA.
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
LONG RANGE MODELS ARE SHOWING MORE VARIABILITY IN THE
EXTENDED TIME PERIOD. SHOWERS TAPER OFF SUNDAY AS THE UPPER LEVEL
TROUGH MOVES EAST OF THE FORECAST AREA...WITH A FEW SHOWERS OVER THE
CASCADES MONDAY. CONFIDENCE IS LOW FOR THE REMAINDER OF THE FORECAST.
MODELS VARY GREATLY IN THEIR SOLUTIONS...SO WILL KEEP TUE AND WED DRY
FOR NOW...UNTIL MODELS AGREE ON A SOLUTION.
&&
.AVIATION...SOLID MVFR STRATUS DECK WITH MVFR CEILINGS WILL COVER
AREAS W OF THE CASCADES THIS MORNING. INLAND AREAS WILL STRUGGLE TO
BREAK OUT DURING THE AFTERNOON...EXPECT VFR CONDITIONS WILL
EVENTUALLY DEVELOP AS WEAK SHORT WAVE RIDGING MOVES BACK OVER THE
AREA AHEAD OF THE UPPER LOW OFF THE COAST NEAR 135W. COASTAL
TERMINALS WILL LIKELY REMAIN MVFR TODAY.
KPDX AND APPROACHES...MVFR CEILINGS BELOW 2000 FT THIS MORNING BUT
SHOULD REMAIN ABOVE IFR. CLOUDS ARE EXPECTED TO SLOWLY LIFT AND
BREAK UP DURING THE AFTERNOON WITH VFR RETURNING TO THE KPDX AREA
AROUND MID AFTERNOON. RW
&&
.MARINE...WEAK HIGH PRES WILL REMAIN IN THE VECINITY OF THE COASTAL
WATERS THROUGH EARLY FRI. LOW PRESS 500 NM W OF CAPE BLANCO WILL
WEAKEN AS IT APPROACHES THE NORTHERN CA/SOUTHERN OREGON COAST
FRI...AND SHOULD HAVE LITTLE IMPACT ON OUR WATERS. AN ASSOCIATED
WEAK COLD FRONT WILL MOVE THROUGH THE AREA FRI NIGHT OR SAT.
GRADIENTS WILL REMAIN FAIRLY WEAK THROUGH SAT...SO EXPECT MAINLY
LIGHT WINDS/SEAS FOR THE NEXT 2-3 DAYS. HIGH PRES BUILDING IN BEHIND
THE FRONT MAY CAUSE STRONGER N-NW WINDS TO DEVELOP BY SUN/MON. EBBS
REMAIN STRONG FOR COLUMBIA RIVER BAR...BUT SEAS REMAIN LIGHT SO NO
ADVISORIES. RW
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR/WA...NONE.
&&
.PRELIMINARY POINT POPS (PROBABILITY OF MEASURABLE PRECIPITATION)
AST 11111 PDX 1111- SLE 1111- EUG 1111-
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KSEW 180938
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
230 AM PDT THU SEP 18 2008
.SYNOPSIS...LOW LEVEL ONSHORE FLOW BROUGHT MARINE STRATUS INTO
WESTERN WASHINGTON EARLY THIS MORNING. THE CLOUDS WILL BURN BACK
PARTWAY TOWARD THE COAST THIS AFTERNOON THEN MOVE INLAND AGAIN
OVERNIGHT THROUGH FRIDAY MORNING. A WEAK UPPER TROUGH WILL MOVE
THROUGH THE AREA FRIDAY NIGHT AND SATURDAY. AN UNSETTLED WEATHER
PATTERN MAY PERSIST INTO NEXT WEEK.
&&
.SHORT TERM...MARINE STRATUS OVER WRN WA....IN THE GRIDS I HAVE
PATCHY FOG ELEV BLO 500FT W/ AREAS FOG 500-3000FT. AT 2AM KPAE HAD
5SM BR OVC004...SO YOU WUD NEED TO BE ON AT LEAST 1000FT HILL TO BE
IN THE STRATUS AND AT 2AM THE BEST GUESS IS THAT THE MARINE AIR IS
ONLY 3000FT DEEP...KSMP AT 2AM WAS CLEAR AND 14C/08C SO STRATUS WAS
NOT TO THE CREST. UW MM5NAM 0-3KFT CLOUD MIXING RATIO PRODUCT SHOWS
THE STRATUS WILL PROBABLY NOT BURN OFF AT THE COAST AND MAY EVEN
BURN OFF SEATTLE SWD TDY. BIGGER PICTURE...UPPER LOW OFF CALIF AND
WA UNDER SLY FLOW ALF. OTHER THAN THE STRATUS NOT ENUF MSTR FOR
PRECIP YET. UPPER HEIGHTS FALL SLOWLY THRU FRI AND MODELS GENERATE
ONLY DRIBS AND DRABS OF PRECIP WHICH WOULD BE NOTHING MORE THAN
PATCHY DRIZZLE IN THE LATE NIGHT AND MORNING HOURS. BEST CHC FOR
SHOWERS IS FRI NIGHT/SAT MORNING AS REMNANT OF THE UPPER LOW KICKS
THRU WA AS WEAK TROF. HGTS/THICKNESS ONLY FALLS 100M THRU THE WHOLE
EVENT SO NOT SHOWING MORE THAN CHANCE POPS. HOWEVER...FLOW ALOFT
BACKS TO MORE SELY FRIDAY EVENING AND MODELS SHOW SOME PRECIP
BLOSSOMING OVER CASCADES. THE WETTEST SOLN IS THE WRF EXTENSION W/
24HR PRECIP ENDING 00Z SUN SHOWING A GOOD SOAKING RAIN IN THE
CENTRAL AND NRN CASCADES HOWEVER THE NAM SHOWS ONLY A RELATIVELY
SMALL AREA IN THE NORTH CASCADES W/ JUST 0.3" AM SAT. 19
.LONG TERM...NO CHANGE TO EXTENDED FCST THIS SHIFT AND FCST IS CLOSE
TO CLIMO WHICH IS OKAY AT THIS TIME RANGE. IF THE MODELS HOLD TO THE
00Z SOLN HOWEVER THEN HIGHER POPS MIGHT BE COMING FOR SUNDAY AND
AGAIN BY WED. GFS HAS UPPER TROF SUN WITH SHOWERS...AGAIN THE WRF
EXTENSION LOOKS WET W/ A HALF AN INCH OR MORE IN THE CASCADES AND
FOOTHILLS AND NORTH INTERIOR. THE GFS HAS ANOTHER TROF HANGING
BACK IN THE NE PAC WHILE THE ECMWF SHOWS A MORE CONSOLIDATED UPPER
TROF MOVING THRU THE REGION ON MONDAY. THEN BOTH MODELS SHOW A DIRTY
RIDGE JUST OFFSHORE W/ 500MB IN 570S. THE 00Z GFS HAS A SOAKING RAIN
EVENT IN THE MOUNTAINS BY WED. WRF EXTENSION SHOWS 1-2.5" IN THE
MTNS IN 24HRS BUT LESS THAN A QUARTER INCH LOWLANDS. FCST MAY HAVE
SOME CATCHING UP TO DO IF THE GFS PERSISTS WITH THIS IDEA. THE ECMWF
IS SLOWER AND TAKES MORE OF THE MOISTURE INTO B.C. BEFORE BRINGING
RAIN INTO WRN WA THU. THAT ADDRESSES THE WETTER POSSIBILITY. BUT IT
IS ALSO A GOOD GUESS AT THIS TIME RANGE THAT THE MODELS WILL NOW
AMPLIFY THE FLOW A BIT MORE AND THAT COULD KEEP SYSTEMS GOING TO THE
NORTH OF WA. AS I SAID FOR NOW FCST LOOKS FINE WITH SOME CLOUDS AND
TEMPS IN THE 60S. 19
&&
.AVIATION...A RIDGE OF HIGH PRESSURE REMAINS OVER THE AREA WITH
LIGHT SOUTHERLY ALOFT. LOW LEVEL ONSHORE FLOW HAS FORCED A MARNE
LAYER INLAND WITH STRATUS AND FOG. THIS WILL SLOWLY LIFT THROUGH THE
DAY AND BREAK UP LATER THIS AFTERNOON. STRATUS TOP REPORTS EARLY
THIS MORNING WOULD BE USEFUL IN TIMING THE BREAKOUT.
KSEA...STRATUS LAYER LIKELY ABOUT AS LOW AS IT WILL GET AND SHOULD
START LIFTING THROUGH THE MORNING HOURS AS THE MARINE LAYER DEEPENS
AND THE SUN SLOWLY WARMS THE SURFACE. EXPECTING IFR CIGS THROUGH
16Z-18Z...THEN LIFTING ABOVE 1000 FT. AT THIS POINT BEST GUESSTIMATE
OF BREAKOUT WOULD BE MID AFTERNOON. SW WINDS THROUGH MOST OF THE
DAY...TRENDING TOWARD WEST MID TO LATE AFTERNOON BEFORE SETTLING
BACK TO SW DURING THE EVENING. CERNIGLIA
&&
.MARINE...VARYING DEGREES OF ONSHORE FLOW WILL CONTINUE INTO THE
EARLY PART OF NEXT WEEK. AN UPPER TROUGH WILL CROSS THE REGION LATER
SUNDAY WHICH WILL INCREASE THE ONSHORE PRESSURE GRADIENT AFTER IT
PASSES BY. THE ENHANCED GRADIENT WILL CONTINUE THROUGH MONDAY. THE
MAIN AFFECT OF THIS ONSHORE FLOW WILL BE FELT IN THE STRAIT OF JUAN
DE FUCA WHERE THE WEST WINDS WILL REACH SCA CRITERIA MOST DAYS IN
THE LATE AFTERNOON INTO THE EVENING HOURS. CERNIGLIA
&&
.FIRE WEATHER...A LITTLE COOLER WITH HIGHER HUMIDITIES TODAY AS UPPER
LEVEL RIDGE AND SURFACE THERMAL TROUGH CONTINUE TO PUSH SLOWLY
EASTWARD. SOME HELP TODAY ALSO FROM THE DEBRIS CLOUDS AND SMOKE
MOVING NORTHWARD OUT OF OREGON. SHOULD BE ONE MORE WARM AND DRY DAY
THURSDAY IN THE MOUNTAINS BEFORE MARINE MOISTURE MOVES INLAND ENOUGH
TO COOL TEMPERATURES DOWN AND RAIN HUMIDITIES OUT OF RED FLAG
CRITERIA. END OF THE WEEK APPEARS COOLER WITH MORE CLOUDINESS AND A
SLIGHT CHANCE OF SHOWERS FRIDAY NIGHT...INTO THE WEEKEND. PRANGE
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FOR THE OLYMPIC AND CASCADE MOUNTAINS THROUGH
THURSDAY AFTERNOON.
SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT OF JUAN DE FUCA.
&&
$$
WEATHER.GOV/SEATTLE
000
FXUS66 KOTX 180552 AAB
AFDOTX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SPOKANE WA
1052 PM PDT WED SEP 17 2008
...UPDATED AVIATION...
.SYNOPSIS...
THE RIDGE OF HIGH PRESSURE THAT HAS BROUGHT DRY AND WARM
CONDITIONS TO THE INLAND NORTHWEST WILL SLOWLY BREAK DOWN OVER THE
NEXT SEVERAL DAYS RESULTING IN A GRADUAL COOLING TREND. TEMPERATURES
WILL RETURN TO NEAR NORMAL LEVELS BY THE WEEKEND.
&&
.PREV DISCUSSION... /ISSUED 807 PM PDT WED SEP 17 2008/
WITH THE MID-LEVELS MOISTENING SLIGHTLY AND LAPSE RATES ALOFT
SHOWING A SLOW BUT STEADY STABILIZING TREND...WE`VE ENDED THE RED
FLAG WARNING FOR HIGH HAINES AND RH. FILLING WEAK VORT MAX OVER
THE COLUMBIA BASIN THIS EVENING WILL REACH THE SRN BC/NE WA BORDER
LATER TONIGHT WITH NO PCPN EXPECTED. TO THE S...THE SHORT- WAVE
TROF OVER OREGON IS EXPECTED TO TRACK NE AND APPROACH EXTREME SE
WA LATE TONIGHT. THIS WILL BE OUR BEST CHANCE TO SEE PCPN TONIGHT.
BUT WITH THE VORT MAX MOVING THROUGH DIFLUENT STEERING FLOW...IT
TOO WILL LIKELY SHEAR AND WEAKEN. FOR NOW WE`LL LEAVE LOW POPS IN
THE SRN ZONES OVERNIGHT BUT KEEP AT LEAST PARTLY CLOUDY SKIES IN
THE FCST. BZ
TONIGHT THROUGH SATURDAY...DISTURBANCE VISIBLE AS A FIELD OF
INSTABILITY CLOUDS AS WELL AS ENHANCED LARGE FIRE DEVELOPMENT IN
OREGON CONTINUES TO WORK ITS WAY NORTHWARD. THIS DISTURBANCE WILL
REMAIN MARKED IN THE FORECAST PRIMARILY A AS ALTOCUMULUS CLOUDS
DRIFTING BY OVERNIGHT AND THURSDAY...WITH PERHAPS A VERY SMALL
AREA NEAR THE BLUE MOUNTAINS WHERE A SLIGHT CHANCE OF
THUNDERSTORMS REMAINS MENTIONED. THURSDAY NIGHT INTO FRIDAY A
CLOSED LOW APPROACHING IN A WEST TO EAST TRAJECTORY HAS BEEN
RESOLVED PASSING TO THE SOUTH OF THE FORECAST AREA IN DIFFERING
DISTANCES...WITH MOST MODEL RUNS OF THE PAST DEPICTING ITS PASSAGE
WELL TO THE SOUTH IN SUCH A WAY AS TO NOT HAVE AN IMPACT AND
WARRANT ANY POPS. CURRENT MODEL RUNS ARE PASSING IT CLOSER AND
SHOWING IT...OR SOME ENERGY EJECTED OUT BUT ASSOCIATED WITH
IT...HAVING AN IMPACT ON SENSIBLE WEATHER FOR EASTERN WASHINGTON
AND NORTHERN IDAHO. FOR NOW WILL STAY THE COURSE WITH PAST
FORECAST DEVELOPED WITH THE OLDER MODEL RUNS WHICH SHOWED LESS
IMPACT...THUS ANY THUNDER MENTION REMAINS OVER A SLIVER OF THE
EXTREME SOUTHERN PORTION OF THE FORECAST AREA ON FRIDAY. SIMILAR
THINKING IN TERMS OF RELYING ON OLDER RATHER THAN CURRENT MODELS
IN DEPICTING WEATHER FOR FRIDAY NIGHT AND SATURDAY STILL GOES AS
OLDER MODELS HINTED AT SOME ENERGY EJECTING INTO THE FORECAST AREA
FROM THIS LOW AS IT PASSED TO THE SOUTH BUT NOT WITH THE INTENSITY
OF THE CURRENT 12Z GFS CONSIDERING HOW MUCH PRECIP IS GENERATED
FOR SATURDAY IN THIS RECENT 12Z GFS RUN. RECORD HIGH TEMPS FOR
OMAK SEEM TO BE ON THE COOL SIDE FOR OKANOGAN VALLEY COMPARED TO
OTHERS LOCALES WHICH MAKE THE RECORD HIGH TEMPS FORECAST FOR THERE
TOMORROW STAND OUT SOMEWHAT...OTHERWISE FORECAST TEMPERATURES
CONTINUE THE GRADUAL COOL DOWN ASSOCIATED WITH THE LOSS OF THE
GENERAL LONGWAVE RIDGE. /PELATTI
SATURDAY NIGHT THROUGH WEDNESDAY...MODELS DEFINITELY COMING IN LINE
WITH THE IDEA OF THE TROUGH SWINGING THROUGH SATURDAY NIGHT AND
SUNDAY. SADLY...AM HESITANT TO GO GUNG-HO ON BOARD WITH THIS
SOLUTION GIVEN THE MODELS POOR PERFORMANCE TRYING TO FIGURE OUT
WHAT IS HAPPENING THIS WEEKEND AND EARLY NEXT WEEK. JUST A FEW
DAYS AGO THE MODELS WERE AGREEING WITH THE IDEA OF THE CLOSED LOW
REMAINING DOWN IN CALIFORNIA. SO HAVE STARTED TO TREND THE
FORECAST TOWARDS A COOL AND UNSETTLED PATTERN...AS MODELS SHOWING
ANOTHER TROUGH/WEATHER SYSTEM MOVING IN FOR MONDAY AS WELL.
INCREASED CLOUD COVER...LOWERED TEMPS A BIT MORE...AND INCREASED
CHANCE OF PRECIP THROUGH THE WEEKEND. MAX TEMPERATURES WILL BE
BELOW AVERAGE THROUGH THE PERIOD WHILE MIN TEMPS WILL BE AT OR
SLIGHTLY BELOW AVERAGE THROUGH EARLY NEXT WEEK. /NISBET
&&
.AVIATION...
VFR WX CAN BE EXPECTED AT ALL TAF SITES THROUGH AT LEAST 06Z FRI. THE
ONLY NOTE OF INTEREST WILL BE AN INCREASE OF MID AND HI CLOUDS
MOVING N OUT OF OREGON AND INTO SERN WA. CEILINGS SHOULD NOT BE
ANY LOWER THAN 11-13K FT AGL FOR THE KLWS AN KPUW TAFS OVERNIGHT.
BZ
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 54 86 53 84 53 74 / 0 10 10 10 10 20
COEUR D`ALENE 51 87 49 84 51 74 / 0 10 10 10 10 20
PULLMAN 51 88 48 83 50 74 / 0 10 10 10 10 20
LEWISTON 59 93 57 88 57 78 / 10 10 10 10 10 20
COLVILLE 44 87 45 85 46 75 / 0 10 10 0 0 10
SANDPOINT 40 83 43 80 47 73 / 0 10 10 10 10 20
KELLOGG 47 88 50 85 50 71 / 0 10 10 10 10 30
MOSES LAKE 53 89 51 87 54 78 / 0 10 10 10 0 10
WENATCHEE 58 88 57 85 55 77 / 0 0 0 10 10 0
OMAK 51 90 53 88 52 76 / 0 0 0 0 0 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
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