[top]
000
FXUS65 KBOI 200231
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
830 PM MDT FRI SEP 19 2008
.DISCUSSION...AFTERNOON FORECAST HANDLING THE CURRENT SITUATION
WELL. SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED THROUGHOUT
THE SOUTHERN HALF OF OUR CWA AS UPPER LOW APPROACHES FROM NRN CALIF.
THE SHOWERS HAVE BEEN ADVANCING NORTH/NORTHWEST INTO OUR REMAINING
ZONES. PROGS SHOW THE AIR MASS REMAINING UNSTABLE THROUGH SATURDAY
WITH THE GREATEST INSTABILITY IN OUR ERN ZONES IN IDAHO. RADAR AND
LIGHTNING DETECTORS CONTINUE TO SHOW THUNDERSTORMS MOVING NWWD
ACROSS THE NEVADA/IDAHO BORDER THIS EVENING. BOI RAOB HAS MOISTENED
WITH .68 INCH PRECIPITABLE WATER AT 00Z TODAY VS .54 INCH AT 12Z
THIS MORNING...AND .26 INCH AT 00Z YESTERDAY. MOST OF THE MOISTENING
TODAY WAS ABOVE 12000 FEET AND LOWER LEVELS WERE STILL VERY DRY.
INITIAL SHOWERS MOISTENED THE MID LEVELS AND SHOWERS LATER ON WILL
MOISTEN THE AIR AT LOWER LEVELS THROUGH THE NIGHT. BY SATURDAY
MORNING THE LOW LEVELS SHOULD BE MOIST ENOUGH FOR RAIN TO REACH THE
GROUND EVERYWHERE...HEAVIEST IN THE BOISE AND WEST CENTRAL IDAHO
MOUNTAINS. ALSO...MUCH COOLER SATURDAY AS THE UPPER LOW AND
RAIN-COOLED AIR REPLACE TODAY/S HOT DRY AIR MASS. A FIRE WEATHER
RED FLAG WARNING WAS ISSUED LATE THIS AFTERNOON FOR TONIGHT FOR
LIGHTNING. THIS WARNING WILL BE CONTINUED...BUT CONDITIONS SHOULD
IMPROVE BY MORNING AS THE AIR MASS AND FUELS MOISTEN.
&&
.AVIATION...VFR WILL PREDOMINATE WITH ISOLATED MVFR CEILINGS AND
PERIODS OF MOUNTAIN OBSCURATION IN RAIN SHOWERS AND ISOLATED
THUNDERSTORMS TONIGHT. SHOWERS WILL INCREASE IN COVERAGE SATURDAY
MORNING AND CONTINUE THROUGH THE DAY. THUNDERSTORMS WILL BE
ISOLATED. SURFACE WINDS WILL BE LIGHT TO MODERATE SOUTHWEST TO
NORTHWEST. WINDS ALOFT WILL BE MODERATE SOUTHWEST.
&&
.PREV DISCUSSION...
SHORT TERM...TONIGHT THROUGH SUNDAY...STRONG UPPER LEVEL SYSTEM
STILL HEADED RIGHT FOR SE OREGON AND SW IDAHO. SHOWERS AND
THUNDERSTORMS HAVE DEVELOPED THIS AFTERNOON...MAINLY OVER SOUTHERN
OWYHEE AND SOUTHERN TWIN FALLS COUNTIES. THESE SHOWERS AND STORMS
ARE EXPECTED TO INCREASE IN AREAL COVERAGE OVERNIGHT AND ON
SATURDAY. MOISTURE CONTINUES TO INCREASE...WITH PWATS FORECAST TO
RISE ABOVE ONE INCH OVER MUCH OF THE AREA ON SATURDAY. ALONG WITH
HPC...WE LIKED THE WAY THE ECMWF HAS CONSISTENTLY HANDLED THIS
SYSTEM...AND USED IT HEAVILY FOR TIMING AND MOISTURE GUIDANCE. HAVE
GONE WELL ABOVE MAV AND MET GUIDANCE POPS FOR LATE TONIGHT AND
SATURDAY IN THE WEST CENTRAL AND BOISE MTNS...AND IN BAKER COUNTY
OREGON. THE HIGHER TERRAIN IN THESE AREAS IS GOING TO GET WET.
CHANCES IN THE VALLEYS ARE NOT AS HIGH...BUT STILL CONSIDERABLE.
TEMPS OVERNIGHT WILL NOT GET TOO COOL BECAUSE OF WIND AND CLOUD
COVER. ON SATURDAY...TEMPS WILL BE QUITE COOL. A COLD FRONT WILL
SWEEP THROUGH...AND CLOUD COVER AND PRECIPITATION COMBINE TO HELP
KEEP THINGS FROM WARMING. AS THE CLOUD COVER DIMINISHES SATURDAY
NIGHT FOR MOST AREAS...WE WILL HAVE GOOD CONDITIONS FOR COOLING
SUNDAY MORNING. HIGHS ON SUNDAY WILL STRUGGLE INTO THE LOWER 70S IN
THE VALLEYS...AND MAKE IT INTO THE 50S FOR MOST OF THE MOUNTAIN
AREAS. AS A FINAL NOTE...SOME ISOLATED SPOTS IN THE MOUNTAINS WILL
GET HEAVY RAIN...AS IN OVER A HALF INCH. IF ONE OF THESE SPOTS
HAPPENS TO BE ON AN AREA AFFECTED BY RECENT FOREST FIRE
BURNS...MUDSLIDES MAY RESULT.
LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...SECONDARY REINFORCING WAVE
SLATED TO MOVE IN BEHIND THE CURRENT TROUGH ON MONDAY. LATEST
GUIDANCE IS NOT AS IMPRESSIVE WITH PRECIPITATION AMOUNTS AS
PREVIOUS RUNS AND KEEP THE BULK OF THE MOISTURE TO THE NORTH.
HIGHEST POPS ARE FOCUSED THROUGH THE WEST CENTRAL AND BOISE
MOUNTAINS ON MONDAY. THE MODELS HAVE CHANGED TUESDAY ONWARD IN
THAT THEY ARE NOW SHOWING THE NORTHWEST UNDER A MOIST ZONAL FLOW.
THE 12Z GFS EVEN BRINGS PRECIPITATION THROUGH WA/ORE/ID ON
WEDNESDAY. PREVIOUS RUNS HAD A DRY RIDGE BUILDING INTO THE REGION.
WHILE NOT BUYING INTO A WET SOLUTION...HAVE TRENDED POPS AND
TEMPERATURES TOWARD CLIMATOLOGY TO ACCOUNT FOR THE UNCERTAINTY.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...RED FLAG WARNING UNTIL 12Z SATURDAY FOR LIGHTNING IN THE
WESTERN TWIN FALLS BLM...FIRE WEATHER ZONE 418.
OR...NONE.
&&
$$
WEATHER.GOV/BOISE
DISCUSSION...LC
AVIATION.....JT
PREV SHORT TERM...SP
PREV LONG TERM....DF/DD
000
FXUS65 KBOI 200230
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
830 PM MDT FRI SEP 19 2008
.DISCUSSION...AFTERNOON FORECAST HANDLING THE CURRENT SITUATION
WELL. SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED THROUGHOUT
THE SOUTHERN HALF OUR CWA AS UPPER LOW APPROACHES FROM NRN CALIF.
THE SHOWERS HAVE BEEN ADVANCING NORTH/NORTHWEST INTO OUR REMAINING
ZONES. PROGS SHOW THE AIR MASS REMAINING UNSTABLE THROUGH SATURDAY
WITH THE GREATEST INSTABILITY IN OUR ERN ZONES IN IDAHO. RADAR AND
LIGHTNING DETECTORS CONTINUE TO SHOW THUNDERSTORMS MOVING NWWD
ACROSS THE NEVADA/IDAHO BORDER THIS EVENING. BOI RAOB HAS MOISTENED
WITH .68 INCH PRECIPITABLE WATER AT 00Z TODAY VS .54 INCH AT 12Z
THIS MORNING...AND .26 INCH AT 00Z YESTERDAY. MOST OF THE MOISTENING
TODAY WAS ABOVE 12000 FEET AND LOWER LEVELS WERE STILL VERY DRY.
INITIAL SHOWERS MOISTENED THE MID LEVELS AND SHOWERS LATER ON WILL
MOISTEN THE AIR AT LOWER LEVELS THROUGH THE NIGHT. BY SATURDAY
MORNING THE LOW LEVELS SHOULD BE MOIST ENOUGH FOR RAIN TO REACH THE
GROUND EVERYWHERE...HEAVIEST IN THE BOISE AND WEST CENTRAL IDAHO
MOUNTAINS. ALSO...MUCH COOLER SATURDAY AS THE UPPER LOW AND
RAIN-COOLED AIR REPLACE TODAY/S HOT DRY AIR MASS. A FIRE WEATHER
RED FLAG WARNING WAS ISSUED LATE THIS AFTERNOON FOR TONIGHT FOR
LIGHTNING. THIS WARNING WILL BE CONTINUED...BUT CONDITIONS SHOULD
IMPROVE BY MORNING AS THE AIR MASS AND FUELS MOISTEN.
&&
.AVIATION...VFR WILL PREDOMINATE WITH ISOLATED MVFR CEILINGS AND
PERIODS OF MOUNTAIN OBSCURATION IN RAIN SHOWERS AND ISOLATED
THUNDERSTORMS TONIGHT. SHOWERS WILL INCREASE IN COVERAGE SATURDAY
MORNING AND CONTINUE THROUGH THE DAY. THUNDERSTORMS WILL BE
ISOLATED. SURFACE WINDS WILL BE LIGHT TO MODERATE SOUTHWEST TO
NORTHWEST. WINDS ALOFT WILL BE MODERATE SOUTHWEST.
&&
.PREV DISCUSSION...
SHORT TERM...TONIGHT THROUGH SUNDAY...STRONG UPPER LEVEL SYSTEM
STILL HEADED RIGHT FOR SE OREGON AND SW IDAHO. SHOWERS AND
THUNDERSTORMS HAVE DEVELOPED THIS AFTERNOON...MAINLY OVER SOUTHERN
OWYHEE AND SOUTHERN TWIN FALLS COUNTIES. THESE SHOWERS AND STORMS
ARE EXPECTED TO INCREASE IN AREAL COVERAGE OVERNIGHT AND ON
SATURDAY. MOISTURE CONTINUES TO INCREASE...WITH PWATS FORECAST TO
RISE ABOVE ONE INCH OVER MUCH OF THE AREA ON SATURDAY. ALONG WITH
HPC...WE LIKED THE WAY THE ECMWF HAS CONSISTENTLY HANDLED THIS
SYSTEM...AND USED IT HEAVILY FOR TIMING AND MOISTURE GUIDANCE. HAVE
GONE WELL ABOVE MAV AND MET GUIDANCE POPS FOR LATE TONIGHT AND
SATURDAY IN THE WEST CENTRAL AND BOISE MTNS...AND IN BAKER COUNTY
OREGON. THE HIGHER TERRAIN IN THESE AREAS IS GOING TO GET WET.
CHANCES IN THE VALLEYS ARE NOT AS HIGH...BUT STILL CONSIDERABLE.
TEMPS OVERNIGHT WILL NOT GET TOO COOL BECAUSE OF WIND AND CLOUD
COVER. ON SATURDAY...TEMPS WILL BE QUITE COOL. A COLD FRONT WILL
SWEEP THROUGH...AND CLOUD COVER AND PRECIPITATION COMBINE TO HELP
KEEP THINGS FROM WARMING. AS THE CLOUD COVER DIMINISHES SATURDAY
NIGHT FOR MOST AREAS...WE WILL HAVE GOOD CONDITIONS FOR COOLING
SUNDAY MORNING. HIGHS ON SUNDAY WILL STRUGGLE INTO THE LOWER 70S IN
THE VALLEYS...AND MAKE IT INTO THE 50S FOR MOST OF THE MOUNTAIN
AREAS. AS A FINAL NOTE...SOME ISOLATED SPOTS IN THE MOUNTAINS WILL
GET HEAVY RAIN...AS IN OVER A HALF INCH. IF ONE OF THESE SPOTS
HAPPENS TO BE ON AN AREA AFFECTED BY RECENT FOREST FIRE
BURNS...MUDSLIDES MAY RESULT.
LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...SECONDARY REINFORCING WAVE
SLATED TO MOVE IN BEHIND THE CURRENT TROUGH ON MONDAY. LATEST
GUIDANCE IS NOT AS IMPRESSIVE WITH PRECIPITATION AMOUNTS AS
PREVIOUS RUNS AND KEEP THE BULK OF THE MOISTURE TO THE NORTH.
HIGHEST POPS ARE FOCUSED THROUGH THE WEST CENTRAL AND BOISE
MOUNTAINS ON MONDAY. THE MODELS HAVE CHANGED TUESDAY ONWARD IN
THAT THEY ARE NOW SHOWING THE NORTHWEST UNDER A MOIST ZONAL FLOW.
THE 12Z GFS EVEN BRINGS PRECIPITATION THROUGH WA/ORE/ID ON
WEDNESDAY. PREVIOUS RUNS HAD A DRY RIDGE BUILDING INTO THE REGION.
WHILE NOT BUYING INTO A WET SOLUTION...HAVE TRENDED POPS AND
TEMPERATURES TOWARD CLIMATOLOGY TO ACCOUNT FOR THE UNCERTAINTY.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...RED FLAG WARNING UNTIL 12Z SATURDAY FOR LIGHTNING IN THE
WESTERN TWIN FALLS BLM...FIRE WEATHER ZONE 418.
OR...NONE.
&&
$$
WEATHER.GOV/BOISE
DISCUSSION...LC
AVIATION.....JT
PREV SHORT TERM...SP
PREV LONG TERM....DF/DD
[top]
000
FXUS65 KPIH 200222
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
822 PM MDT FRI SEP 19 2008
.UPDATE...WATER VAPOR IMAGERY SHOWS THE CENTER OF THE LOW ROUGHLY
OVER EUREKA CALIFORNIA IN CLOSE AGREEMENT WITH THE 18Z GFS MODEL
RUN. SHOWERS WITH ISOLATED THUNDERSTORMS HAVE DEVELOPED ACROSS
SOUTHWEST IDAHO EXTENDING INTO THE TWIN FALLS...BURLEY...AND
KETCHUM AREA AND SHOWERS SHOULD PROGRESS INTO EAST IDAHO BY
MORNING. THIS COVERED IN THE CURRENT FORECAST. MOST DIFFICULT PART
IS QPF. SHOWERS SO FAR HAVE PRODUCED A TRACE TO .04 INCH BUT THERE
WAS ONE REMOTE STATION ON THE WEST SIDE OF THE STATE THAT REPORTED
.17 INCH RAIN THE PAST TWO HOURS. CONVECTION IS KEY FOR HEAVIER
AMOUNTS. FORECAST NOTION IS TO POSSIBLY RAISE QPF AMOUNTS ON THE
WEST SIDE OF FORECAST AREA CLOSER TO .25 FOR THE HIGHER
ELEVATIONS. OTHERWISE NO CHANGES THIS EVENING. RS
&&
.PREV DISCUSSION... /ISSUED 240 PM MDT FRI SEP 19 2008/
DISCUSSION...AN UPPER CLOSED LOW OFF THE NRN CA COAST THIS
AFTERNOON WILL MOVE INLAND TONIGHT AND OPEN UP INTO A NEG TILT TROF.
THE FORWARD PORTION OF THE TROF MOVES OVER ID BY SAT MORNING WITH
ALONG WITH AN ASSOCIATED VERTICAL MOTION FIELD. A GOOD AMOUNT OF PAC
MSTR SHOWING UP ON THE WV LOOP...SO EXPECTING PRECIP TO BECOME
WIDESPREAD TOWARD SAT MORNING AND CONTINUING THRU THE DAY.
CONVECTION ALREADY DEVELOPING ACRS SW ID THIS AFTN...JUST SPREADING
INTO THE SRN HIGHLANDS. SPOTTY CONVECTION IS EXPECTED TO POP UP ACRS
THE FCST AREA THRU EVENING...THEN INCREASE IN COVERAGE AFT MIDNIGHT.
THE UPPER TROF MOVES OUT OF ID SAT NIGHT...HOVEVER ANOTHER UPPER LOW
DROPS INTO WRN CANADA AND PUTS THE ENTIRE NW US UNDER A TROF PATTERN
SUN NIGHT. THIS WILL MAINTAIN THE THREAT OF PRECIP THRU MONDAY...
ALONG WITH MUCH COOLER TEMPS. THE GFS HAS THE UPPER FLOW RETURNING
TO FAST ZONAL ON TUE...WITH MINOR WAVES GENERATING PRECIP AGAIN TUE
NIGHT AND WED. TIMING ON THESE WILL BE DIFFICULT DUE TO THE VERY
SMALL AMPLITUDE. THUS...WILL CARRY LOW CHC POPS IN THE NORTH TUE
NIGHT AND WED. HEDGES
AVIATION...ISOLATED THUNDERSTORMS HAVE FORMED OVER WESTERN IDAHO
AND ARE EXPECTED TO FIRE UP OVER ERN HIGHLANDS THIS AFTN. IF ANY OF
THESE TSTORMS SET UP OVER OR NEAR TAF SITES...CAN EXPECT MVFR
CONDITIONS UNTIL THE STORM PASSES. NEXT SYSTEM APPROACHES OVERNIGHT
AND WILL AFFECT WX TOMORROW MORNING THRU TOMORROW NIGHT.
RAINSHOWERS AND TSTORMS ARE EXPECTED ACROSS SERN ID SO LOW CIGS
COULD CREATE SOME MVFR CONDITIONS AT OR NEAR AIRPORTS. RENWICK
FIRE WEATHER...CLOUDS...MOISTURE AND INSTABILITY ON THE INCREASE AS
IR SATELLITE SHOWING MASS OF CLOUDS FORMING OVER ID WITH SOME
CONVECTION JUST BEGINNING TO FORM. THIS IS ALL IN RESPONSE TO
CLOSED LOW JUST OFF PAC COAST BRINGING UPPER LEVEL DISTURBANCES OVER
AREA. THIS LOW WILL MOVE THRU ID TOMORROW MORNING AND BRING A COLD
FRONT WITH IT. MODELS HAVE HIGHLIGHTED RAINSHOWERS AND TSTORMS
AHEAD AND ALONG THIS FRONT FOR SEVERAL DAYS NOW. AS SUCH...HAVE
ISSUED A RED FLAG WARNING FOR ALL ID FIRE ZONES...409 410 411 412
413 475 476 AND 477 DUE TO WIDESPREAD THUNDERSTORMS VALID FROM
20/18Z THOUGH 21/3Z. AFTER TROUGH PASSES...RATHER UNSETTLED WX
EXPECTED FOR MON AND TUESDAY AS UPPER LEVEL ENERGY WILL CONTINUE TO
MOVE OVER ID FROM TIME TO TIME CAUSING SHOWERY TYPE PRECIP WITH A
STRAY TSTM NOT OUT OF THE QUESTION. RENWICK
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM 12 PM TO 9 PM MDT SATURDAY FOR IDZ409>413-
475>477.
&&
$$
000
FXUS65 KPIH 192038
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
240 PM MDT FRI SEP 19 2008
.DISCUSSION...AN UPPER CLOSED LOW OFF THE NRN CA COAST THIS
AFTERNOON WILL MOVE INLAND TONIGHT AND OPEN UP INTO A NEG TILT TROF.
THE FORWARD PORTION OF THE TROF MOVES OVER ID BY SAT MORNING WITH
ALONG WITH AN ASSOCIATED VERTICAL MOTION FIELD. A GOOD AMOUNT OF PAC
MSTR SHOWING UP ON THE WV LOOP...SO EXPECTING PRECIP TO BECOME
WIDESPREAD TOWARD SAT MORNING AND CONTINUING THRU THE DAY.
CONVECTION ALREADY DEVELOPING ACRS SW ID THIS AFTN...JUST SPREADING
INTO THE SRN HIGHLANDS. SPOTTY CONVECTION IS EXPECTED TO POP UP ACRS
THE FCST AREA THRU EVENING...THEN INCREASE IN COVERAGE AFT MIDNIGHT.
THE UPPER TROF MOVES OUT OF ID SAT NIGHT...HOVEVER ANOTHER UPPER LOW
DROPS INTO WRN CANADA AND PUTS THE ENTIRE NW US UNDER A TROF PATTERN
SUN NIGHT. THIS WILL MAINTAIN THE THREAT OF PRECIP THRU MONDAY...
ALONG WITH MUCH COOLER TEMPS. THE GFS HAS THE UPPER FLOW RETURNING
TO FAST ZONAL ON TUE...WITH MINOR WAVES GENERATING PRECIP AGAIN TUE
NIGHT AND WED. TIMING ON THESE WILL BE DIFFICULT DUE TO THE VERY
SMALL AMPLITUDE. THUS...WILL CARRY LOW CHC POPS IN THE NORTH TUE
NIGHT AND WED. HEDGES
&&
.AVIATION...ISOLATED THUNDERSTORMS HAVE FORMED OVER WESTERN IDAHO
AND ARE EXPECTED TO FIRE UP OVER ERN HIGHLANDS THIS AFTN. IF ANY OF
THESE TSTORMS SET UP OVER OR NEAR TAF SITES...CAN EXPECT MVFR
CONDITIONS UNTIL THE STORM PASSES. NEXT SYSTEM APPROACHES OVERNIGHT
AND WILL AFFECT WX TOMORROW MORNING THRU TOMORROW NIGHT.
RAINSHOWERS AND TSTORMS ARE EXPECTED ACROSS SERN ID SO LOW CIGS
COULD CREATE SOME MVFR CONDITIONS AT OR NEAR AIRPORTS. RENWICK
&&
.FIRE WEATHER...CLOUDS...MOISTURE AND INSTABILITY ON THE INCREASE AS
IR SATELLITE SHOWING MASS OF CLOUDS FORMING OVER ID WITH SOME
CONVECTION JUST BEGINNING TO FORM. THIS IS ALL IN RESPONSE TO
CLOSED LOW JUST OFF PAC COAST BRINGING UPPER LEVEL DISTURBANCES OVER
AREA. THIS LOW WILL MOVE THRU ID TOMORROW MORNING AND BRING A COLD
FRONT WITH IT. MODELS HAVE HIGHLIGHTED RAINSHOWERS AND TSTORMS
AHEAD AND ALONG THIS FRONT FOR SEVERAL DAYS NOW. AS SUCH...HAVE
ISSUED A RED FLAG WARNING FOR ALL ID FIRE ZONES...409 410 411 412
413 475 476 AND 477 DUE TO WIDESPREAD THUNDERSTORMS VALID FROM
20/18Z THOUGH 21/3Z. AFTER TROUGH PASSES...RATHER UNSETTLED WX
EXPECTED FOR MON AND TUESDAY AS UPPER LEVEL ENERGY WILL CONTINUE TO
MOVE OVER ID FROM TIME TO TIME CAUSING SHOWERY TYPE PRECIP WITH A
STRAY TSTM NOT OUT OF THE QUESTION. RENWICK
&&
.PIH WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING FOR
THUNDERSTORMS NOON UNTIL 9 PM MDT SATURDAY FOR ZONES 409-413 AND
475-477.
&&
$$
000
FXUS65 KBOI 192014
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
214 PM MDT FRI SEP 19 2008
.SHORT TERM...TONIGHT THROUGH SUNDAY...STRONG UPPER LEVEL SYSTEM
STILL HEADED RIGHT FOR SE OREGON AND SW IDAHO. SHOWERS AND
THUNDERSTORMS HAVE DEVELOPED THIS AFTERNOON...MAINLY OVER SOUTHERN
OWYHEE AND SOUTHERN TWIN FALLS COUNTIES. THESE SHOWERS AND STORMS
ARE EXPECTED TO INCREASE IN AREAL COVERAGE OVERNIGHT AND ON
SATURDAY. MOISTURE CONTINUES TO INCREASE...WITH PWATS FORECAST TO
RISE ABOVE ONE INCH OVER MUCH OF THE AREA ON SATURDAY. ALONG WITH
HPC...WE LIKED THE WAY THE ECMWF HAS CONSISTENTLY HANDLED THIS
SYSTEM...AND USED IT HEAVILY FOR TIMING AND MOISTURE GUIDANCE. HAVE
GONE WELL ABOVE MAV AND MET GUIDANCE POPS FOR LATE TONIGHT AND
SATURDAY IN THE WEST CENTRAL AND BOISE MTNS...AND IN BAKER COUNTY
OREGON. THE HIGHER TERRAIN IN THESE AREAS IS GOING TO GET WET.
CHANCES IN THE VALLEYS ARE NOT AS HIGH...BUT STILL CONSIDERABLE.
TEMPS OVERNIGHT WILL NOT GET TOO COOL BECAUSE OF WIND AND CLOUD
COVER. ON SATURDAY...TEMPS WILL BE QUITE COOL. A COLD FRONT WILL
SWEEP THROUGH...AND CLOUD COVER AND PRECIPITATION COMBINE TO HELP
KEEP THINGS FROM WARMING. AS THE CLOUD COVER DIMINISHES SATURDAY
NIGHT FOR MOST AREAS...WE WILL HAVE GOOD CONDITIONS FOR COOLING
SUNDAY MORNING. HIGHS ON SUNDAY WILL STRUGGLE INTO THE LOWER 70S
IN THE VALLEYS...AND MAKE IT INTO THE 50S FOR MOST OF THE MOUNTAIN
AREAS. AS A FINAL NOTE...SOME ISOLATED SPOTS IN THE MOUNTAINS WILL
GET HEAVY RAIN...AS IN OVER A HALF INCH. IF ONE OF THESE SPOTS
HAPPENS TO BE ON AN AREA AFFECTED BY RECENT FOREST FIRE
BURNS...MUDSLIDES MAY RESULT.
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...SECONDARY REINFORCING WAVE
SLATED TO MOVE IN BEHIND THE CURRENT TROUGH ON MONDAY. LATEST
GUIDANCE IS NOT AS IMPRESSIVE WITH PRECIPITATION AMOUNTS AS
PREVIOUS RUNS AND KEEP THE BULK OF THE MOISTURE TO THE NORTH.
HIGHEST POPS ARE FOCUSED THROUGH THE WEST CENTRAL AND BOISE
MOUNTAINS ON MONDAY. THE MODELS HAVE CHANGED TUESDAY ONWARD IN
THAT THEY ARE NOW SHOWING THE NORTHWEST UNDER A MOIST ZONAL FLOW.
THE 12Z GFS EVEN BRINGS PRECIPITATION THROUGH WA/ORE/ID ON
WEDNESDAY. PREVIOUS RUNS HAD A DRY RIDGE BUILDING INTO THE REGION.
WHILE NOT BUYING INTO A WET SOLUTION...HAVE TRENDED POPS AND
TEMPERATURES TOWARD CLIMATOLOGY TO ACCOUNT FOR THE UNCERTAINTY.
&&
.AVIATION...WIDESPREAD VFR. ISOLATED MVFR AND PERIODS OF MOUNTAIN
OBSCURATION IN RAIN SHOWERS THIS AFTERNOON CONTINUING THROUGH THE
NIGHT. THE SHOWERS WILL INCREASE IN COVERAGE AND INTENSITY BY
SATURDAY MORNING CONTINUING THROUGHOUT THE DAY. EXPECT WIDELY
SCATTERED THUNDERSTORMS THIS AFTERNOON BECOMING ISOLATED OVERNIGHT
INTO SATURDAY. SURFACE WINDS WILL BE LIGHT EXCEPT FOR GUSTY WINDS IN
THE VICINITY OF THUNDERSTORMS. SOUTHERLY WINDS ALOFT WILL BE LIGHT
TODAY BECOMING MODERATE CYCLONIC BY SATURDAY MORNING.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.
&&
$$
WEATHER.GOV/BOISE
SHORT TERM...SP
LONG TERM....DF/DD
AVIATION.....DF
000
FXUS65 KBOI 191928
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
128 PM MDT FRI SEP 19 2008
.DISCUSSION...QUICK UPDATE JUST TO PUT MENTIONABLE POPS AND
THUNDER INTO THE WESTERN MAGIC VALLEY AND UPPER TREASURE VALLEY
FOR THE REMAINDER OF THE AFTERNOON. THE UPPER LEVEL SYSTEM IS
APPROACHING AND HELPING TO FORCE A DECENT AMOUNT OF CONVECTION.
MORE ON THIS IN THE FULL AFTERNOON PACKAGE.
&&
.AVIATION...VFR WITH INCREASING MID AND HIGH LEVEL CLOUDS THROUGH
THE DAY DUE TO AN APPROACHING UPPER LEVEL TROUGH. ISOLATED MVFR AND
PERIODS OF MOUNTAIN OBSCURATION IN RAIN SHOWERS ARE EXPECTED LATE
THIS AFTERNOON CONTINUING THROUGH THE NIGHT. THE SHOWERS WILL
INCREASE IN COVERAGE AND INTENSITY BY SATURDAY MORNING CONTINUING
THROUGHOUT THE DAY. ISOLATED THUNDERSTORMS ARE EXPECTED AFTER 21Z
TODAY CONTINUING OVERNIGHT AND THROUGH THE DAY ON SATURDAY. SURFACE
WINDS WILL BE LIGHT EXCEPT FOR GUSTY WINDS IN THE VICINITY OF
THUNDERSTORMS. SOUTHERLY WINDS ALOFT WILL BE LIGHT TODAY.
&&
.PREV DISCUSSION...
SHORT TERM...TODAY THROUGH SATURDAY...AN INCREASINGLY MOIST
SOUTHERLY FLOW WILL DEVELOP TODAY AHEAD OF ADVANCING UPPER LOW OFF
THE WEST COAST. TEMPERATURES WILL HEAT UP ONCE AGAIN THIS AFTERNOON
AS WE START THE DAY WITH MOSTLY CLEAR SKIES...BUT THE AIRMASS WILL
DESTABILIZE DUE TO HEATING AND THE ADDED MOISTURE FROM THE SOUTH.
THEREFORE...STILL LOOKING FOR A 15 TO 30 PERCENT CHANCE OF SHOWERS
AND THUNDERSTORMS...ESPECIALLY ACROSS THE SOUTH WHERE THERE WILL BE
MORE MOISTURE TO WORK WITH. AIRMASS CONTINUES TO MOISTEN UP TONIGHT
THROUGH SATURDAY AS THE UPPER LOW MOVES INTO THE AREA. MODELS HAD
BEEN SHOWING THE SYSTEM TO COME IN AS A TROUGH...BUT NOW THE MODELS
ARE TENDING TOWARD HOLDING THE SYSTEM TOGETHER AS A TIGHTER CLOSED
UPPER LOW. IN THE END THIS MAY WIND UP BEING A SLOWER SYSTEM...BUT
FOR NOW WILL KEEP TIMING ABOUT THE SAME. CONFIDENCE FOR MEASURABLE
PRECIP HAS INCREASED SINCE THE MODELS ARE IN AGREEMENT THAT THE LOW
COULD BRING A FAIR AMOUNT OF RAINFALL...ESPECIALLY IN THE SOUTHWEST
IDAHO MOUNTAINS ON SATURDAY. QPF TOTALS IN SOME LOCATIONS MAY BE AS
HIGH AS A HALF INCH...IF NOT MORE. TEMPERATURES...MEANWHILE...WILL
BE CONSIDERABLY LOWER ON SATURDAY AND DROPPED THEM EVEN SLIGHTLY
BELOW THE COOLEST GUIDANCE.
LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...TROF WILL BE SLOW TO
MOVE AS IT GETS A REINFORCING INFUSION OF COLD AIR WITH A SECONDARY
TROF HEADING IN FROM THE NORTH PACIFIC SUNDAY NIGHT INTO MONDAY.
AFTER MONDAY THE UPPER FLOW BECOMES MORE WESTERLY AND WILL GRADUALLY
PUSH THE COOLER AIR OUT ALLOWING TEMPERATURES TO RISE AND PUSHING
THE PRECIP OUT AS WELL.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.
&&
$$
WEATHER.GOV/BOISE
DISCUSSION...SP
AVIATION...DF
PREV SHORT TERM...BW
PREV LONG TERM....PF
000
FXUS65 KBOI 191520
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
920 AM MDT FRI SEP 19 2008
.DISCUSSION...NO CHANGES TO THE FORECAST THIS MORNING. STILL HAVE
A POTENT UPPER LEVEL STORM MOVING INTO THE REGION TODAY. AS
MENTIONED IN THE PREVIOUS DISCUSSION...QPF WILL BE HIGH WITH THIS
SYSTEM. POPS WILL LIKELY NEED TO BE RAISED AS WELL. WILL
COORDINATE THESE CHANGES WITH SURROUNDING OFFICES AND ADD THEM TO
THE AFTERNOON PACKAGE.
&&
.AVIATION...VFR WITH INCREASING MID AND HIGH LEVEL CLOUDS THROUGH
THE DAY DUE TO AN APPROACHING UPPER LEVEL TROUGH. ISOLATED MVFR AND
PERIODS OF MOUNTAIN OBSCURATION IN RAIN SHOWERS ARE EXPECTED LATE
THIS AFTERNOON CONTINUING THROUGH THE NIGHT. THE SHOWERS WILL
INCREASE IN COVERAGE AND INTENSITY BY SATURDAY MORNING CONTINUING
THROUGHOUT THE DAY. ISOLATED THUNDERSTORMS ARE EXPECTED AFTER 21Z
TODAY CONTINUING OVERNIGHT AND THROUGH THE DAY ON SATURDAY. SURFACE
WINDS WILL BE LIGHT EXCEPT FOR GUSTY WINDS IN THE VICINITY OF
THUNDERSTORMS. SOUTHERLY WINDS ALOFT WILL BE LIGHT TODAY.
&&
.PREV DISCUSSION...
SHORT TERM...TODAY THROUGH SATURDAY...AN INCREASINGLY MOIST
SOUTHERLY FLOW WILL DEVELOP TODAY AHEAD OF ADVANCING UPPER LOW OFF
THE WEST COAST. TEMPERATURES WILL HEAT UP ONCE AGAIN THIS AFTERNOON
AS WE START THE DAY WITH MOSTLY CLEAR SKIES...BUT THE AIRMASS WILL
DESTABILIZE DUE TO HEATING AND THE ADDED MOISTURE FROM THE SOUTH.
THEREFORE...STILL LOOKING FOR A 15 TO 30 PERCENT CHANCE OF SHOWERS
AND THUNDERSTORMS...ESPECIALLY ACROSS THE SOUTH WHERE THERE WILL BE
MORE MOISTURE TO WORK WITH. AIRMASS CONTINUES TO MOISTEN UP TONIGHT
THROUGH SATURDAY AS THE UPPER LOW MOVES INTO THE AREA. MODELS HAD
BEEN SHOWING THE SYSTEM TO COME IN AS A TROUGH...BUT NOW THE MODELS
ARE TENDING TOWARD HOLDING THE SYSTEM TOGETHER AS A TIGHTER CLOSED
UPPER LOW. IN THE END THIS MAY WIND UP BEING A SLOWER SYSTEM...BUT
FOR NOW WILL KEEP TIMING ABOUT THE SAME. CONFIDENCE FOR MEASURABLE
PRECIP HAS INCREASED SINCE THE MODELS ARE IN AGREEMENT THAT THE LOW
COULD BRING A FAIR AMOUNT OF RAINFALL...ESPECIALLY IN THE SOUTHWEST
IDAHO MOUNTAINS ON SATURDAY. QPF TOTALS IN SOME LOCATIONS MAY BE AS
HIGH AS A HALF INCH...IF NOT MORE. TEMPERATURES...MEANWHILE...WILL
BE CONSIDERABLY LOWER ON SATURDAY AND DROPPED THEM EVEN SLIGHTLY
BELOW THE COOLEST GUIDANCE.
LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...TROF WILL BE SLOW TO
MOVE AS IT GETS A REINFORCING INFUSION OF COLD AIR WITH A SECONDARY
TROF HEADING IN FROM THE NORTH PACIFIC SUNDAY NIGHT INTO MONDAY.
AFTER MONDAY THE UPPER FLOW BECOMES MORE WESTERLY AND WILL GRADUALLY
PUSH THE COOLER AIR OUT ALLOWING TEMPERATURES TO RISE AND PUSHING
THE PRECIP OUT AS WELL.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.
&&
$$
WEATHER.GOV/BOISE
DISCUSSION...SP
AVIATION.....DF
PREV SHORT TERM...BW
PREV LONG TERM....PF
000
FXUS65 KPIH 190922
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
310 AM MDT FRI SEP 19 2008
.DISCUSSION...CLOSED UPPER LEVEL LOW IN EASTERN PACIFIC EXPECTED TO
REACH THE WEST COAST THIS AFTERNOON AND PUSH INLAND TONIGHT. BY SAT
MORNING...SHOWERS SHOULD BE DEVELOPING FROM WEST TO EAST ACROSS THE
FORECAST AREA. NAM-12 INDICATING .01 TO 0.10 MAINLY FOR SNAKE RIVER
PLAIN...0.10 TO 0.25 FOR MUCH OF THE MOUNTAINS...EXCEPT LIMITED PART
OF SAWTOOTHS UP TO 0.50 INCH THROUGH SAT AFTERNOON. HAVE INCREASED
QPF TO COME CLOSE TO THESE AMOUNTS. TIMING HAS SLOWED
THOUGH...ESPECIALLY FOR THE EASTERN HALF OF THE FORECAST
AREA...WHICH SHOULD REMAIN DRY ALL OF TODAY AND START GETTING
PRECIPITATION LATE TONIGHT. CLOUD COVER WILL LEAD TO SOME COOLING
TODAY...BUT PRECIPITATION AND A COLD CORE LOW COMING IN FOR SAT WILL
CAUSE MUCH MORE COOLING. A SECOND SHORTWAVE ARRIVING MON WILL BE
DRIER AND THUS NOT AS MUCH PRECIPITATION...BUT COMING FROM THE GULF
OF AK...IT WILL DRIVE TEMPERATURES DOWN SOME MORE. HAVE NOT BIT OFF
ON AS MUCH COLD AIR AS THE GFS HAS...WITH HIGH TEMP ON TUE AT KPIH
OF 62...BUT HAVE DELAYED WARMING TREND FROM STARTING UNTIL WED.
STORM TRACK STILL PUSHING NORTHWARD AND AWAY FROM IDAHO TOWARDS THE
END OF THE FORECAST WEEK. FLOW IS MORE ZONAL AND THUS A LITTLE MORE
OPEN TO RUN TO RUN VARIABILITY...BUT DO NOT SEE ANY MAJOR STORMS
AFTER TUE. ECMWF ALSO WANTS A STRONGER AND BIGGER UPPER LEVEL
RIDGE...MAKE THREAT GENERALLY EVEN LOWER THAN THE AGGRESSIVE GFS.
MESSICK
&&
.AVIATION...ISOLATED THUNDERSTORMS FORECAST TO DEVELOP BY AFTERNOON
ACROSS PORTIONS OF EAST IDAHO WITH OCCASIONAL MVFR CONDITIONS. MAIN
THREAT APPEARS TO BE IN HIGHER TERRAIN AND ESPECIALLY ALONG/WEST OF
A LINE FROM KBYI TO KSNT. MAIN THREAT REMAINS GUSTY WINDS.
OTHERWISE...VFR CONDITIONS FCST. DMH
&&
.FIRE WEATHER...MOISTURE AND INSTABILITY ON THE INCREASE THIS
AFTERNOON AND EVENING AHEAD OF NEGATIVE TILT PACIFIC TROUGH PUSHING
INTO NORTHERN CALIFORNIA. MAINLY ISOLATED THUNDERSTORMS ACROSS THE
DISTRICT TODAY...FOCUSED ON CENTRAL MTNS. UPPER TROUGH LIFTS ACROSS
DISTRICT ON SATURDAY WITH COLD FRONT MOVING NORTHEAST THROUGH REGION
DURING THE MORNING. EXPECTING MORE WIDESPREAD PERCIP ASSOCIATED WITH
THE FRONT AND UPPER TROUGH. CURRENT FCST PAINTING ENOUGH INSTABILITY
FOR INCREASED EMBEDDED THUNDERSTORM COVERAGE. WITH CURRENT
SCENARIO...FIRE WEATHER WATCH WILL BE NEEDED FOR SATURDAY AND WILL
LET FOLLOWING SHIFT MAKE FINAL DETERMINATION. ONCE UPPER TROUGH
LIFTS PAST REGION SAT NIGHT INTO SUN...COOL AND RELATIVELY UNSETTLED
CONDITIONS FCST FOR BEGINNING OF NEXT WEEK AS BROAD TROUGH REMAINS
IN PLACE OVER PACNW. DMH
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS65 KBOI 190858
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
258 AM MDT FRI SEP 19 2008
.SHORT TERM...TODAY THROUGH SATURDAY...AN INCREASINGLY MOIST
SOUTHERLY FLOW WILL DEVELOP TODAY AHEAD OF ADVANCING UPPER LOW OFF
THE WEST COAST. TEMPERATURES WILL HEAT UP ONCE AGAIN THIS AFTERNOON
AS WE START THE DAY WITH MOSTLY CLEAR SKIES...BUT THE AIRMASS WILL
DESTABILIZE DUE TO HEATING AND THE ADDED MOISTURE FROM THE SOUTH.
THEREFORE...STILL LOOKING FOR A 15 TO 30 PERCENT CHANCE OF SHOWERS
AND THUNDERSTORMS...ESPECIALLY ACROSS THE SOUTH WHERE THERE WILL BE
MORE MOISTURE TO WORK WITH. AIRMASS CONTINUES TO MOISTEN UP TONIGHT
THROUGH SATURDAY AS THE UPPER LOW MOVES INTO THE AREA. MODELS HAD
BEEN SHOWING THE SYSTEM TO COME IN AS A TROUGH...BUT NOW THE MODELS
ARE TENDING TOWARD HOLDING THE SYSTEM TOGETHER AS A TIGHTER CLOSED
UPPER LOW. IN THE END THIS MAY WIND UP BEING A SLOWER SYSTEM...BUT
FOR NOW WILL KEEP TIMING ABOUT THE SAME. CONFIDENCE FOR MEASURABLE
PRECIP HAS INCREASED SINCE THE MODELS ARE IN AGREEMENT THAT THE LOW
COULD BRING A FAIR AMOUNT OF RAINFALL...ESPECIALLY IN THE SOUTHWEST
IDAHO MOUNTAINS ON SATURDAY. QPF TOTALS IN SOME LOCATIONS MAY BE AS
HIGH AS A HALF INCH...IF NOT MORE. TEMPERATURES...MEANWHILE...WILL
BE CONSIDERABLY LOWER ON SATURDAY AND DROPPED THEM EVEN SLIGHTLY
BELOW THE COOLEST GUIDANCE.
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...TROF WILL BE SLOW TO
MOVE AS IT GETS A REINFORCING INFUSION OF COLD AIR WITH A SECONDARY
TROF HEADING IN FROM THE NORTH PACIFIC SUNDAY NIGHT INTO MONDAY.
AFTER MONDAY THE UPPER FLOW BECOMES MORE WESTERLY AND WILL GRADUALLY
PUSH THE COOLER AIR OUT ALLOWING TEMPERATURES TO RISE AND PUSHING
THE PRECIP OUT AS WELL.
&&
.AVIATION...VFR WITH HIGH CLOUDS THIS MORNING. MOISTURE WILL
INCREASE THROUGH THE DAY AS OFFSHORE TROF HEADS INLAND. SHOWERS
THUNDERSTORMS WILL BECOME SCATTERED OVER THE AREA IN THE AFTERNOON.
CLOUD BASES WILL LOWER WITH SOME MVFR LIKELY OVER THE MOUNTAINS AND
SOME MOUNTAIN OBSCURATION LIKELY AS WELL.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.
&&
$$
WEATHER.GOV/BOISE
SHORT TERM...BW
LONG TERM....PF
AVIATION.....PF
000
FXUS65 KBOI 190256
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
856 PM MDT THU SEP 18 2008
.DISCUSSION...WILL HOLD OFF ON ANY UPDATES AS THE FORECAST IS ON
TRACK. MODELS CONTINUE IN GOOD AGREEMENT BRINGING THE SHORTWAVE
TROUGH FROM OFF THE CALIFORNIA/OREGON COAST INLAND OVER OUR AREA
FRIDAY NIGHT AND SATURDAY. ALTHOUGH THERE IS LITTLE IF ANY JET
SUPPORT WITH THIS SYSTEM...TIME HEIGHT CROSS SECTIONS SHOW STRONG
LIFT THROUGH A DEEP LAYER WHICH WILL BE UNSTABLE ENOUGH FOR
CONVECTION AND QUITE MOIST ABOVE 700 MB. THE SURFACE TROUGH REMAINS
IN PLACE ACROSS EASTERN OREGON AND WESTERN IDAHO FRIDAY NIGHT
THROUGH 12Z SATURDAY COINCIDING WITH MAXIMUM DYNAMICS ALOFT. LOW
LEVEL DIVERGENCE AND COOLING HOLD OFF UNTIL LATE SATURDAY MORNING.
SO THIS EVENT WILL DEFINITELY GIVE US THE BEST CHANCE OF MEASURABLE
PRECIPITATION THAT WE HAVE SEEN IN A LONG TIME...WHICH FOR BOISE
WILL HAVE BEEN 58 DAYS. ADJUSTMENTS TO CONSIDER IN THE NEXT FORECAST
PACKAGE INCLUDE POPS AND QPF FOR FRIDAY NIGHT AND SATURDAY...WHICH
MAY BE TOO LOW ESPECIALLY IN THE MOUNTAINS...AND MAX TEMPERATURES
SATURDAY...WHICH MAY BE TOO HIGH.
&&
.AVIATION...WIDESPREAD VFR AND LIGHT SURFACE WINDS THROUGH 16Z
FRIDAY MORNING. EXPECT INCREASING MID AND HIGH CLOUDS OVERNIGHT DUE
TO AN APPROACHING UPPER LEVEL TROUGH. LIGHT SOUTHERLY WINDS ALOFT.
FRIDAY...ISOLATED MVFR AND PERIODS OF MOUNTAIN OBSCURATION IN RAIN
SHOWERS BEGINNING LATE AFTERNOON AND CONTINUING THROUGH THE EVENING.
ISOLATED THUNDERSTORMS EXPECTED AFTER 21Z.
&&
.PREV DISCUSSION...
SHORT TERM...TONIGHT THROUGH SATURDAY...A STRONG UPPER LEVEL SYSTEM
IS HEADED FOR THE REGION LATE FRIDAY THROUGH SATURDAY. IN ADVANCE OF
THIS...WE WILL SEE UPPER FLOW BACKING TO SOUTHERLY BY MIDDAY FRIDAY.
THIS WILL DRAW MOISTURE NORTHWARD INTO THE AREA AND INCREASE THE
CHANCE FOR MEASURABLE PRECIPITATION. INSTABILITY IS MARGINAL...BUT
WITH THE STRENGTH OF THE SYSTEM...IT WOULD NOT BE WISE TO LEAVE
THUNDER OUT OF THE FORECAST. FOR NOW...WENT WITH SLIGHT CHANCE
THUNDER AREAWIDE FOR FRIDAY AFTERNOON THROUGH SATURDAY AFTERNOON.
MAY EVEN SEE SOME HEAVY RAIN AMOUNTS IN ISOLATED MAINLY
TERRAIN-INFLUENCED AREAS...BUT CANNOT PINPOINT THESE AREAS UNTIL THE
EXACT TRACK OF THE UPPER LOW IS DETERMINED. TEMPS WILL WARM NICELY
TOMORROW EVEN AS HUMIDITY INCREASES...MAKING IT OUR FIRST SOMEWHAT
MUGGY DAY IN QUITE SOME TIME. CLOUD COVER WILL INCREASE IN THE
AFTERNOON AS CONVECTIVE CLOUDS ARE INITIATED...AND SCATTERED TO
BROKEN CLOUDS SHOULD CONTINUE OVERNIGHT AND MOST OF SATURDAY.
SATURDAY WILL BE MUCH COOLER AS A COLD FRONT...ASSOCIATED WITH THE
UPPER LOW...MOVES THROUGH. PRECIPITATION WILL BE SCATTERED AROUND
THE AREA AS WELL...MAINLY IN THE HIGHER TERRAIN OF THE WEST CENTRAL
AND BOISE MTNS...WHERE NUMEROUS SHOWERS AND A FEW THUNDERSTORMS WILL
FORM.
LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...NEGATIVELY TILTED OPEN
WAVE WILL BEGIN TO EXIT THE REGION SUNDAY BUT LINGERING MOISTURE
WILL KEEP A CHANCE OF PRECIPITATION THROUGH NE OREGON AND THROUGH
MUCH OF IDAHO. HAVE INCLUDED A SLIGHT CHANCE OF THUNDER IN CENTRAL
IDAHO EASTWARD SUNDAY AFTERNOON WITH MODEL INDICATED INSTABILITY
THROUGH THE REGION. A SECOND PIECE OF ENERGY FOLLOWS THROUGH BEHIND
THIS FIRST WAVE EARLY MONDAY MORNING WITH THE BEST CHANCES FOR
PRECIPITATION THROUGH THE WEST CENTRAL AND BOISE MOUNTAINS. COOLEST
AIR MASS WILL REMAIN OVER THE INTERMOUNTAIN WEST MONDAY AND TUESDAY
WHILE UNDER A GENERAL CYCLONIC FLOW. TEMPERATURES WILL AVERAGE 5 TO
8 DEGREES BELOW NORMAL. RIDGE AMPLIFIES OVER THE EASTERN PACIFIC
DURING THE SAME PERIOD AND WILL GRADUALLY SHIFT INLAND OVER THE WEST
WEDNESDAY INTO THURSDAY. THIS WILL BRING DRYING CONDITIONS AND
TEMPERATURES AT OR ABOVE NORMAL FOR THE END OF THE EXTENDED PERIOD.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.
&&
$$
WEATHER.GOV/BOISE
DISCUSSION...JT
AVIATION.....MT
PREV SHORT TERM...SP
PREV LONG TERM....DF/DD
000
FXUS65 KPIH 190227
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
827 PM MDT THU SEP 18 2008
.UPDATE...HIGH PRESSURE RIDGE CONTINUES TO DOMINATE THE WEATHER
OVER SOUTHEAST IDAHO. A FEW VIRGA SHOWERS DEVELOPED BRIEFLY THIS
AFTERNOON. ISOLATED LIGHTNING STRIKES WERE OBSERVED JUST SOUTH OF
MALAD BUT THE WINDS ALOFT WERE MOVING THOSE CELLS AWAY FROM
SOUTHEAST IDAHO. COULD STILL BE AN ISOLATED RAIN SHOWER OVER
HIGHER MOUNTAIN TOPS THIS EVENING BUT NO THREAT OF THUNDERSTORMS. RS
&&
.PREV DISCUSSION... /ISSUED 143 PM MDT THU SEP 18 2008/
DISCUSSION...
UPPER LEVEL FLOW IS OUT OF THE SOUTHWEST WHICH IS BRINGING SOME
MID LEVEL MOISTURE INTO THE AREA. HAVENT SEEN MUCH IN THE WAY OF
CONVECTION YET. THERE IS STILL SOME HOURS OF SUN LEFT...SO AN
ISOLATED THUNDERSTORM OVER THE HIGH COUNTRY REMAINS POSSIBLE.
FRIDAY SHOULD BE A NEARLY IDENTICAL SETUP AS TODAY. BETTER
CHANCES FOR SHOWERS AND THUNDERSTORMS EXISTS ON SATURDAY AS THE
NEXT SYSTEM ARRIVES. MODELS IN MUCH BETTER AGREEMENT TODAY AND
BRING AN OPEN WAVE TROUGH THE AREA ON SATURDAY. CHANCES FOR
PRECIPITATION LOOK PRETTY GOOD IN THE HIGH COUNTRY ON SATURDAY.
DOWNSLOPE WILL LIKELY LIMIT PRECIPITATION OVER THE SNAKE VALLEY.
NAM TAKES MOST OF THE ACTIVITY OUT OF THE AREA ON SUNDAY WHEREAS
THE GFS KEEPS SOME LINGERING PRECIPITATION AROUND THE HIGH
COUNTRY. LEANING MORE TOWARDS THE GFS AT THAT TIME RANGE WHICH
PROBABLY HAS A BETTER HANDLE ON THE SYSTEM THAN THE NAM. AFTER
THIS SYSTEM MOVES THROUGH...TEMPS SHOULD COOL OFF NOTICEABLY.
REGION COMES UNDER THE INFLUENCE OF A BROAD UPPER LEVEL TROUGH
WHICH KEEPS CONTINUED LOW CHANCES FOR PRECIPITATION IN THROUGH
TUESDAY. GFS ADVERTISES A BREAK IN THE ACTION AROUND MID WEEK AS A
WEAK RIDGE BUILDS OVER THE AREA.
AVIATION...PARTLY CLOUDY SKIES THE RULE ACROSS SERN ID. VFR
CONDITIONS EXPECTED. UPPER LEVEL DISTURBANCES MOVING THRU GENERAL
FLOW WILL CAUSE ISOLD TSTORMS ACROSS ERN AND SRN HIGHLANDS THIS
AFTN. STORMS WILL BE SHORT-LIVED IN NATURE AND MAIN CONCERN WILL BE
GUSTY WINDS AT SFC. RENWICK
FIRE WEATHER...UPPER RIDGE SLOWLY MOVING OFF TO EAST. IN ITS
WAKE...SHORTWAVES MOVING THRU GENERAL FLOW. DISTURBANCES WILL KICK
OFF SOME THUNDERSTORMS THIS AFTN IN ERN AND SRN HIGHLANDS.
HOWEVER...COVERAGE NOT HIGH ENOUGH TO ISSUE ANY FIRE WX WARNINGS.
AREA OF LOW PRESSURE WILL SWING TO OUR N ON SATURDAY...ASSOCIATED
FRONTAL PASSAGE IS EXPECTED TO OCCUR LATE SAT MORNING/EARLY SAT
AFTN. CAN EXPECT GUSTY WINDS AND WIDELY SCATTERED TSTMS TO RIDE
ALONG FRONT. TOO EARLY YET TO ISSUE ANY FIRE WX WARNINGS/WATCHES
BUT EXPECT THEY WILL BE FORTHCOMING TOMORROW. RENWICK
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS65 KBOI 182034
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
234 PM MDT THU SEP 18 2008
.SHORT TERM...TONIGHT THROUGH SATURDAY...A STRONG UPPER LEVEL
SYSTEM IS HEADED FOR THE REGION LATE FRIDAY THROUGH SATURDAY. IN
ADVANCE OF THIS...WE WILL SEE UPPER FLOW BACKING TO SOUTHERLY BY
MIDDAY FRIDAY. THIS WILL DRAW MOISTURE NORTHWARD INTO THE AREA AND
INCREASE THE CHANCE FOR MEASURABLE PRECIPITATION. INSTABILITY IS
MARGINAL...BUT WITH THE STRENGTH OF THE SYSTEM...IT WOULD NOT BE
WISE TO LEAVE THUNDER OUT OF THE FORECAST. FOR NOW...WENT WITH
SLIGHT CHANCE THUNDER AREAWIDE FOR FRIDAY AFTERNOON THROUGH SATURDAY
AFTERNOON. MAY EVEN SEE SOME HEAVY RAIN AMOUNTS IN ISOLATED MAINLY
TERRAIN-INFLUENCED AREAS...BUT CANNOT PINPOINT THESE AREAS UNTIL
THE EXACT TRACK OF THE UPPER LOW IS DETERMINED. TEMPS WILL WARM
NICELY TOMORROW EVEN AS HUMIDITY INCREASES...MAKING IT OUR FIRST
SOMEWHAT MUGGY DAY IN QUITE SOME TIME. CLOUD COVER WILL INCREASE
IN THE AFTERNOON AS CONVECTIVE CLOUDS ARE INITIATED...AND
SCATTERED TO BROKEN CLOUDS SHOULD CONTINUE OVERNIGHT AND MOST OF
SATURDAY. SATURDAY WILL BE MUCH COOLER AS A COLD FRONT...
ASSOCIATED WITH THE UPPER LOW...MOVES THROUGH. PRECIPITATION WILL
BE SCATTERED AROUND THE AREA AS WELL...MAINLY IN THE HIGHER
TERRAIN OF THE WEST CENTRAL AND BOISE MTNS...WHERE NUMEROUS
SHOWERS AND A FEW THUNDERSTORMS WILL FORM.
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...NEGATIVELY TILTED
OPEN WAVE WILL BEGIN TO EXIT THE REGION SUNDAY BUT LINGERING
MOISTURE WILL KEEP A CHANCE OF PRECIPITATION THROUGH NE OREGON AND
THROUGH MUCH OF IDAHO. HAVE INCLUDED A SLIGHT CHANCE OF THUNDER IN
CENTRAL IDAHO EASTWARD SUNDAY AFTERNOON WITH MODEL INDICATED
INSTABILITY THROUGH THE REGION. A SECOND PIECE OF ENERGY FOLLOWS
THROUGH BEHIND THIS FIRST WAVE EARLY MONDAY MORNING WITH THE BEST
CHANCES FOR PRECIPITATION THROUGH THE WEST CENTRAL AND BOISE
MOUNTAINS. COOLEST AIR MASS WILL REMAIN OVER THE INTERMOUNTAIN WEST
MONDAY AND TUESDAY WHILE UNDER A GENERAL CYCLONIC FLOW. TEMPERATURES
WILL AVERAGE 5 TO 8 DEGREES BELOW NORMAL. RIDGE AMPLIFIES OVER THE
EASTERN PACIFIC DURING THE SAME PERIOD AND WILL GRADUALLY SHIFT
INLAND OVER THE WEST WEDNESDAY INTO THURSDAY. THIS WILL BRING DRYING
CONDITIONS AND TEMPERATURES AT OR ABOVE NORMAL FOR THE END OF THE
EXTENDED PERIOD.
&&
.AVIATION...WIDELY SCATTERED HIGH AND MID LEVEL VFR CLOUDS TODAY.
SURFACE WINDS WILL BE LIGHT AND VARIABLE. WINDS ALOFT WILL BE LIGHT
SOUTHWEST. LATE FRIDAY AFTERNOON INTO THE EVENING THERE IS A CHANCE
OF SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS THROUGHOUT SE
OREGON AND SW IDAHO WITH A DISTURBANCE APPROACHING FROM THE WEST.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.
&&
$$
WEATHER.GOV/BOISE
SHORT TERM...SP
LONG TERM....DF/DD
AVIATION.....DF
000
FXUS65 KPIH 181943
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
143 PM MDT THU SEP 18 2008
.DISCUSSION...
UPPER LEVEL FLOW IS OUT OF THE SOUTHWEST WHICH IS BRINGING SOME
MID LEVEL MOISTURE INTO THE AREA. HAVENT SEEN MUCH IN THE WAY OF
CONVECTION YET. THERE IS STILL SOME HOURS OF SUN LEFT...SO AN
ISOLATED THUNDERSTORM OVER THE HIGH COUNTRY REMAINS POSSIBLE.
FRIDAY SHOULD BE A NEARLY IDENTICAL SETUP AS TODAY. BETTER
CHANCES FOR SHOWERS AND THUNDERSTORMS EXISTS ON SATURDAY AS THE
NEXT SYSTEM ARRIVES. MODELS IN MUCH BETTER AGREEMENT TODAY AND
BRING AN OPEN WAVE TROUGH THE AREA ON SATURDAY. CHANCES FOR
PRECIPITATION LOOK PRETTY GOOD IN THE HIGH COUNTRY ON SATURDAY.
DOWNSLOPE WILL LIKELY LIMIT PRECIPITATION OVER THE SNAKE VALLEY.
NAM TAKES MOST OF THE ACTIVITY OUT OF THE AREA ON SUNDAY WHEREAS
THE GFS KEEPS SOME LINGERING PRECIPITATION AROUND THE HIGH
COUNTRY. LEANING MORE TOWARDS THE GFS AT THAT TIME RANGE WHICH
PROBABLY HAS A BETTER HANDLE ON THE SYSTEM THAN THE NAM. AFTER
THIS SYSTEM MOVES THROUGH...TEMPS SHOULD COOL OFF NOTICEABLY.
REGION COMES UNDER THE INFLUENCE OF A BROAD UPPER LEVEL TROUGH
WHICH KEEPS CONTINUED LOW CHANCES FOR PRECIPITATION IN THROUGH
TUESDAY. GFS ADVERTISES A BREAK IN THE ACTION AROUND MID WEEK AS A
WEAK RIDGE BUILDS OVER THE AREA.
&&
.AVIATION...PARTLY CLOUDY SKIES THE RULE ACROSS SERN ID. VFR
CONDITIONS EXPECTED. UPPER LEVEL DISTURBANCES MOVING THRU GENERAL
FLOW WILL CAUSE ISOLD TSTORMS ACROSS ERN AND SRN HIGHLANDS THIS
AFTN. STORMS WILL BE SHORT-LIVED IN NATURE AND MAIN CONCERN WILL BE
GUSTY WINDS AT SFC. RENWICK
&&
.FIRE WEATHER...UPPER RIDGE SLOWLY MOVING OFF TO EAST. IN ITS
WAKE...SHORTWAVES MOVING THRU GENERAL FLOW. DISTURBANCES WILL KICK
OFF SOME THUNDERSTORMS THIS AFTN IN ERN AND SRN HIGHLANDS.
HOWEVER...COVERAGE NOT HIGH ENOUGH TO ISSUE ANY FIRE WX WARNINGS.
AREA OF LOW PRESSURE WILL SWING TO OUR N ON SATURDAY...ASSOCIATED
FRONTAL PASSAGE IS EXPECTED TO OCCUR LATE SAT MORNING/EARLY SAT
AFTN. CAN EXPECT GUSTY WINDS AND WIDELY SCATTERED TSTMS TO RIDE
ALONG FRONT. TOO EARLY YET TO ISSUE ANY FIRE WX WARNINGS/WATCHES
BUT EXPECT THEY WILL BE FORTHCOMING TOMORROW. RENWICK
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS65 KBOI 181534
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
934 AM MDT THU SEP 18 2008
.DISCUSSION...NO CHANGES PLANNED THIS MORNING. A FEW CLOUDS ARE
MOVING NE ACROSS SE OREGON AND SW IDAHO THIS MORNING...AND THEY
REPRESENT A RETURN OF MODERATE MOISTURE TO THE REGION. THIS
MOISTURE WILL INCREASE TOMORROW AND SATURDAY. TEMPS WILL WARM THIS
AFTERNOON MUCH LIKE THEY WERE YDAY.
&&
.AVIATION...HIGH AND MID LEVEL VFR CLOUDS WILL DECREASE FROM THE
SOUTHWEST TODAY. SURFACE WINDS WILL BE LIGHT AND VARIABLE. WINDS
ALOFT WILL BE LIGHT SOUTHWEST. LATE FRIDAY AFTERNOON INTO THE
EVENING THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS THROUGHOUT SE
OREGON AND SW IDAHO WITH A DISTURBANCE APPROACHING FROM THE WEST.
&&
.PREV DISCUSSION...
SHORT TERM...TODAY THROUGH FRIDAY...WEAK NEGATIVELY TILTED TROUGH
WILL CONTINUE TO LIFT NORTHEAST THROUGH THE AREA TODAY AND THEN EXIT
TONIGHT. MOISTURE IS LIMITED TO MID AND UPPER ATMOSPHERIC LEVELS AND
THUS ONLY LOOKING FOR PARTLY CLOUDY SKIES TODAY WITH LITTLE TO NO
THREAT OF SHOWERS/THUNDERSTORMS. THE DRY WEATHER WILL CONTINUE
THROUGH FRIDAY MORNING AS NEXT PACIFIC LOW ENTERS THE WEST COAST. AN
INCREASINGLY MOIST SOUTHERLY FLOW DEVELOPS ON FRIDAY AHEAD OF THE
APPROACHING LOW WITH PWATS OF 0.60 TO 0.8 INCHES BY FRIDAY
AFTERNOON. THE GFS SHOWS NO QPF WHILE THE ECMWF AND NAM DEPICT SOME
QPF IN THE AFTERNOON. INSTABILITY IS NOT ALL THAT GREAT...BUT BASED
ON AVAILABLE MOISTURE AND MARGINAL INSTABILITY THERE IS ENOUGH TO
WARRANT 15 TO 30 PERCENT POPS ACROSS MOST OF THE AREA. TEMPS TODAY
WILL RUN ABOUT THE SAME AS THEY WERE ON WEDNESDAY. COOLER AIR WILL
START TO FILTER INTO SOUTHEAST OREGON ON FRIDAY DUE TO LOWER
THICKNESSES AND MORE CLOUDS. NO SIGNIFICANT WINDS THROUGH THE PERIOD.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...THE CLOSED LOW THAT IS
NOW NEAR 135W WILL MOVE INTO OREGON FRIDAY NIGHT AS AN OPEN TROF
THAT WILL MOVE ACROSS SE OREGON AND SE IDAHO SATURDAY. THIS LONG DRY
SPELL MAY COME TO AN END AS THIS TROF LOOKS STRONG ENOUGH TO POSE A
THREAT OF PRECIPITATION ACROSS THE AREA FRIDAY NIGHT AND EARLY
SATURDAY...ESPECIALLY IN THE WEST CENTRAL MOUNTAINS OF IDAHO EARLY
SATURDAY. AN OPEN SYSTEM IS RACING ACROSS THE PACIFIC AND WILL MOVE
INTO THE AREA SUNDAY NIGHT FOR WHAT LOOKS LIKE AN EVEN GREATER
POTENTIAL FOR PRECIPITATION AND A SIGNIFICANT DROP IN TEMPERATURES.
GRADUAL MODERATION IN TEMPERATURES AND A RETURN TO DRY CONDITIONS IS
EXPECTED BEHIND THAT WAVE FOR THE MIDDLE OF NEXT WEEK.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.
&&
$$
WEATHER.GOV/BOISE
DISCUSSION...SP
AVIATION.....DF
PREV SHORT TERM...BW
PREV LONG TERM....JJ
000
FXUS65 KPIH 180858
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
300 AM MDT THU SEP 18 2008
DISCUSSION...CLOSED LOW IN EASTERN PACIFIC HAS EJECTED ONE SHORTWAVE
INTO THE NORTHERN GREAT BASIN AND YET ANOTHER IS EXPECTED THIS
AFTERNOON. THERE IS ALMOST NO UPPER LEVEL SUPPORT AND ONLY WEAK
INSTABILITY...SO SHOWER AND THUNDERSTORM THREAT IS LOW...THOUGH NOT
ZERO. FOCUS THIS AFTERNOON AND EVENING SHOULD BE BORDER WITH
MONTANA AND WYOMING. CLOSED LOW OPENS TO A WAVE AND LIFTS
EAST-NORTHEASTWARD INTO THE PACIFIC NORTHWEST FRI AND FINALLY
ARRIVES IN SOUTHERN IDAHO FRI NIGHT. FOCUS FOR HEAVIEST
PRECIPITATION IS WELL NORTH OF THE FORECAST AREA...HOWEVER SOME
LIGHT TO MODERATE ACCUMULATION POSSIBLE IN THE CENTRAL IDAHO
MOUNTAINS. SHOWERS AND THUNDERSTORMS LINGER INTO SUN AND MON DUE TO
ANOTHER TROUGH MOVES THROUGH THE MEAN ZONAL FLOW. BEST CHANCE WITH
THIS SECOND WAVE IS SUN NIGHT/MON. BESIDES A THREAT OF
RAIN...TEMPERATURES WILL ALSO COOL CONSIDERABLY...WITH 10-PLUS
DEGREE DROP ON SAT...AND EVEN MORE WITH THE MON TROUGH. COULD EVEN
SEE SOME HIGH ELEVATION SNOW WITH SNOW LEVEL ABOVE 9000 FT.
PRECIPITATION CHANCES WEAKEN STRONGLY AS JET STREAM SHIFTS NORTHWARD
AND EASTERN PACIFIC RIDGE MOVES INTO CALIFORNIA. 500MB HEIGHTS RISE
TO 584DM-PLUS BY WED...SO EXPECT WARMING TREND TO DEVELOP AFTER THE
SECOND TROUGH. ONLY MODERATE WIND EXPECTED WITH THE TWO TROUGHS
EXPECTED. MESSICK
&&
.AVIATION...VFR CONDITIONS SHOULD CONTINUE TODAY FOR ALL TAF SITES.
INCREASED MID LEVEL MOISTURE WILL ALLOW ISOLATED THUNDERSTORMS THIS
AFTERNOON MAINLY OVER THE EASTERN AND SOUTHERN HIGHLANDS. GUSTY
OUTFLOW WINDS MAY AFFECT THE SNAKE VALLEY REGION...BUT LITTLE IMPACT
TO AVIATION CONCERNS. DMH
&&
.FIRE WEATHER...ISOLATED THUNDERSTORMS POSSIBLE THIS AFTERNOON AND
EVENING OVER HIGHER TERRAIN AS UPPER RIDGE WEAKENS AHEAD OF PACIFIC
LOW. BETTER CHANCES FOR THUNDERSTORM OCCUR AS EARLY AS FRIDAY
EVENING...THOUGH STILL SOME UNCERTAINTY WITH TIMING OF THE SYSTEM
EVEN THOUGH MODELS COMING TO BETTER AGREEMENT WITH LATEST RUNS. WILL
HOLD OFF ON POTENTIAL HEADLINE FOR THUNDERSTORMS FOR NOW AND LET
NEXT SHIFT MONITOR ONE MORE MODEL RUN. BEST CHANCES FOR PATTERN
CHANGE ON SATURDAY WITH COMPLETE BREAKDOWN OF RIDGE AS PACIFIC
TROUGH SWINGS NORTHEAST THROUGH GREAT BASIN. FRONTAL PASSAGE DURING
THE DAY SATURDAY MAY BRING INCREASED WINDS TO THE VALLEY AND HIGHER
TERRAIN THOUGH INCREASED HUMIDITIES MAY NEGATE NEED FOR HEADLINE.
ONLY OTHER CONCERN WOULD BE THUNDERSTORM COVERAGE AHEAD OF UPPER
TROUGH. DMH
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
000
FXUS65 KBOI 180850
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
248 AM MDT THU SEP 18 2008
.SHORT TERM...TODAY THROUGH FRIDAY...WEAK NEGATIVELY TILTED TROUGH
WILL CONTINUE TO LIFT NORTHEAST THROUGH THE AREA TODAY AND THEN EXIT
TONIGHT. MOISTURE IS LIMITED TO MID AND UPPER ATMOSPHERIC LEVELS AND
THUS ONLY LOOKING FOR PARTLY CLOUDY SKIES TODAY WITH LITTLE TO NO
THREAT OF SHOWERS/THUNDERSTORMS. THE DRY WEATHER WILL CONTINUE
THROUGH FRIDAY MORNING AS NEXT PACIFIC LOW ENTERS THE WEST COAST. AN
INCREASINGLY MOIST SOUTHERLY FLOW DEVELOPS ON FRIDAY AHEAD OF THE
APPROACHING LOW WITH PWATS OF 0.60 TO 0.8 INCHES BY FRIDAY
AFTERNOON. THE GFS SHOWS NO QPF WHILE THE ECMWF AND NAM DEPICT SOME
QPF IN THE AFTERNOON. INSTABILITY IS NOT ALL THAT GREAT...BUT BASED
ON AVAILABLE MOISTURE AND MARGINAL INSTABILITY THERE IS ENOUGH TO
WARRANT 15 TO 30 PERCENT POPS ACROSS MOST OF THE AREA. TEMPS TODAY
WILL RUN ABOUT THE SAME AS THEY WERE ON WEDNESDAY. COOLER AIR WILL
START TO FILTER INTO SOUTHEAST OREGON ON FRIDAY DUE TO LOWER
THICKNESSES AND MORE CLOUDS. NO SIGNIFICANT WINDS THROUGH THE PERIOD.
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...THE CLOSED LOW THAT IS
NOW NEAR 135W WILL MOVE INTO OREGON FRIDAY NIGHT AS AN OPEN TROF
THAT WILL MOVE ACROSS SE OREGON AND SE IDAHO SATURDAY. THIS LONG DRY
SPELL MAY COME TO AN END AS THIS TROF LOOKS STRONG ENOUGH TO POSE A
THREAT OF PRECIPITATION ACROSS THE AREA FRIDAY NIGHT AND EARLY
SATURDAY...ESPECIALLY IN THE WEST CENTRAL MOUNTAINS OF IDAHO EARLY
SATURDAY. AN OPEN SYSTEM IS RACING ACROSS THE PACIFIC AND WILL MOVE
INTO THE AREA SUNDAY NIGHT FOR WHAT LOOKS LIKE AN EVEN GREATER
POTENTIAL FOR PRECIPITATION AND A SIGNIFICANT DROP IN TEMPERATURES.
GRADUAL MODERATION IN TEMPERATURES AND A RETURN TO DRY CONDITIONS IS
EXPECTED BEHIND THAT WAVE FOR THE MIDDLE OF NEXT WEEK.
&&
.AVIATION...VFR CONDITIONS WILL PREVAIL WITH ONLY SCATTERED TO
BROKEN HIGH LEVEL CLOUDS ACROSS THE AREA TODAY AND TONIGHT. SURFACE
WINDS WILL BE LIGHT AND VARIABLE WITH LIGHT SW WINDS ALOFT.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.
&&
$$
WEATHER.GOV/BOISE
SHORT TERM...BW
LONG TERM....JJ
AVIATION.....JJ
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