000
FXUS66 KSTO 201200
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
400 AM PST TUE JAN 20 2009
.DISCUSSION...
HIGHLY AMPLIFIED RIDGE CENTERED OVER THE INTERIOR WEST CONTINUES TO
BRING DRY AND MILD WEATHER TO THE REGION. PATTERN WILL REMAIN
RELATIVELY UNCHANGED TODAY WITH ANOTHER DAY OF UNSEASONABLY WARM
TEMPERATURES EXPECTED ACROSS THE INTERIOR OF NORTHERN CALIFORNIA.
HOWEVER...CHANGE IS RIGHT AROUND THE CORNER AS THE SOUTHERN PORTION
OF THE SPLITTING TROUGH OVER THE GULF OF ALASKA NEARS THE COAST.
HIGH-LEVEL MOISTURE IS ALREADY STREAMING NORTHWARD JUST OFF THE
COAST AHEAD OF THIS SYSTEM AND TO OUR EAST THROUGH THE GREAT BASIN.
CONSEQUENTLY...WE/LL LIKELY BEGIN TO SEE AN INCREASE IN HIGH CLOUDS
ACROSS THE REGION TODAY WHICH MAY HELP TO CLIP A FEW DEGREES OF
WARMTH OFF OF YESTERDAY/S HIGHS. MORE SIGNIFICANT CLOUD COVER ALONG
WITH INCREASED SYNOPTIC COOLING OF THE AIRMASS WILL RESULT IN
TEMPERATURES COOLING BACK TO NEAR NORMAL LEVELS FROM MID-WEEK ONWARD.
WHILE FORCING FROM THE WEAKENED TROUGH APPEARS TO BE RELATIVELY
MINOR...ENTRAINMENT OF SUBTROPICAL MOISTURE INTO THE SYSTEM WILL
LEAD TO INCREASED PRECIPITABLE WATER ACROSS THE REGION LATER
WEDNESDAY INTO THURSDAY. REGIONAL SOUNDINGS SHOWS A VERY DRY AIRMASS
IN PLACE ACROSS THE REGION SO IT WILL TAKE AWHILE FOR ENOUGH
MOISTENING TO TAKE PLACE BEFORE PRECIPITATION WILL BE POSSIBLE OVER
THE CENTRAL VALLEY. MODELS CONTINUE TO FOCUS ON THE BEST
PRECIPITATION CHANCES OCCURRING OVERNIGHT WEDNESDAY INTO THURSDAY AS
THE UPPER TROUGH MOVES ONSHORE. QPF IS EXPECTED TO BE LIGHT WITH
GENERALLY A TENTH OF AN INCH OR LESS EXPECTED IN THE SACRAMENTO
VALLEY WITH LESS THAN A HALF INCH OVER THE NORTHERN SIERRA.
PRECIPITATION CHANCES ARE EXPECTED TO DIMINISH FRIDAY AS SHORTWAVE
RIDGING BUILDS OVER THE REGION AHEAD OF ANOTHER UPPER LOW OFF THE
COAST.
&&
.EXTENDED FORECAST (SATURDAY THROUGH TUESDAY)...
UNSETTLED WEATHER PATTERN MAY CONTINUE OVER THE WEEKEND AND INTO
EARLY NEXT WEEK WITH A COUPLE SYSTEMS MOVING THROUGH THE AREA.
ALTHOUGH WITH MODEL INCONSISTENCIES THERE IS SOME UNCERTAINTY IN THE
TIMING AND THE TRACK OF THE SYSTEMS THUS THE TIMING AND AREA OF
PRECIPITATION MAY CHANGE AS THE SYSTEMS GET CLOSER. TEMPERATURES
WILL BE NEAR NORMAL THROUGH THE PERIOD. THE ECMWF BRINGS
PRECIPITATION ACROSS INTERIOR NORTHERN CALIFORNIA ON SATURDAY WITH A
LOW OFF THE NORTHERN CALIFORNIA COAST AND DRY EARLY SUNDAY THEN
ALONG THE EASTERN MOUNTAINS SUNDAY NIGHT INTO MONDAY WITH A TROUGH
DIGGING DOWN OVER THE WESTERN US. ON THE OTHER HAND...THE GFS IS DRY
SATURDAY AND PRECIPITATION ALONG EASTERN MOUNTAINS ON SUNDAY INTO
MONDAY WITH AN UPPER LEVEL TROUGH DIGGING OVER THE AREA. THE CURRENT
FORECAST LEANS MORE TOWARDS THE ECMWF AT LEAST FOR SATURDAY WITH A
SLIGHT CHANCE IN THE VALLEY AND CHANCE OVER THE MOUNTAINS. THE GFS
AND ECMWF ARE IN BETTER AGREEMENT FOR SUNDAY INTO MONDAY WITH THE
BEST CHANCE OVER THE NORTHERN SIERRA AND WESTERN PLUMAS COUNTY AND
ONLY A SLIGHT CHANCE OVER THE COASTAL RANGE. THE PLACEMENT OF THE
EASTERN PACIFIC RIDGE VARIES ON TUESDAY WITH THE 00Z GFS SHOWING IT
FURTHER WEST FOR RIDGING INTO NORTHERN CALIFORNIA AND DRY WEATHER
BUT THE GFS ENSEMBLE AND THE ECMWF HAVE IT FURTHER EAST WITH A BROAD
TROUGH OVER THE WESTERN US. THE CURRENT FORECAST KEEPS A SLIGHT
CHANCE OF PRECIPITATION OVER THE MOUNTAINS ON TUESDAY LEANING
TOWARDS THE EASTERN PACIFIC RIDGE BEING FURTHER EAST.
&&
.AVIATION...
RIDGE OF HIGH PRESSURE MOVING EAST OF THE AREA AS A TROUGH OVER THE
EASTERN PACIFIC APPROACHES THE WEST COAST. GENERALLY VFR CONDITIONS
ARE EXPECTED OVER INTERIOR NORTHERN CALIFORNIA FOR THE NEXT 24 HOURS
EXCEPT LOCAL MVFR CONDITIONS WITH BR/HZ IN THE MORNING IN THE
NORTHERN SAN JOAQUIN VALLEY. CONDITIONS ARE EXPECTED TO DECREASE ON
WEDNESDAY INTO THURSDAY WITH THE TROUGH MOVING INTO THE AREA
BRINGING MORE CLOUDS AND A CHANCE OF PRECIPITATION.
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS66 KSTO 200526
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
930 PM PST MON JAN 19 2009
.DISCUSSION...
ANOTHER MILD/WARM DAY ON MON OVER INTERIOR NORCAL...WITH RBL TYING A
RECORD AND SEVERAL OTHER NEAR MISSES OVER THE AREA. THE PATTERN HAS
NOW CHANGED FROM SEVERAL DAYS AGO...MAKING THE RECORD WARMTH MORE
PROBLEMATIC ON TUE...AND THEN BACK TO SEASONAL TEMPS. THE FLOW OVER
NORCAL HAS BECOME SLY...ON THE BACKSIDE OF THE HIGHLY AMPLIFIED
RIDGE CENTERED OVER THE GRT BASIN AND INTO CANADA...AND A LONGER
WAVE SPLITTING TROF FROM THE GULF OF AK TO 30N/130W. THE SLY FLOW
HAS TAPPED INTO THE DEEPER RESERVOIR OF HIGH TPW AIR ASSOCIATED WITH
CONVECTION S OF THE BAJA AND OLD MEX. SOME OF THIS MOISTURE WAS IN
THE FORM OF AC/CI THAT SPREAD OVER THE SIERNEV ON MON. MOISTURE/
CLOUD COVER ASSOCIATED WITH THE OFFSHORE TROF IS STEADILY MOVING EWD
AHEAD OF SHORT WAVE ENERGY W OF 130W. THIS ENERGY IN THE SRN PORTION
OF THE LONGER WAVE TROF IS FORECAST TO MOVE TOWARDS THE COAST THRU
12Z THU...AND IS FORECAST TO GIVE NORCAL SOME PRECIP WED AND INTO
THU AS IT CONTINUES TO ENTRAIN SUBTROPICAL MOISTURE. DURING THE DAY
ON THU...THE PCPN MAY WIND DOWN IF THE TIMING OF TROF PASSAGE
VERIFIES PER THE GFS.
TUE LOOKS LIKE ANOTHER WARM DAY WITH LITTLE CHANGE IN 850 MBS TEMPS
AND THICKNESSES FROM TODAY. THE MET GUIDANCE MAY BE THE BETTER
CHOICE OF THE VARIOUS MODELS FOR TUE`S MAX TEMPS...ALTHO THERE MAY
BE A LITTLE MORE CLOUD COVER THAN TODAY WHICH WOULD HAVE A NEGATIVE
EFFECT ON TEMPS. AFTER TUE...SYNOPTIC COOLING WILL LOWER TEMPS TO
NORMAL BY THU. JHM
.EXTENDED DISCUSSION (FRIDAY THROUGH MONDAY)...
MODEL CHANGES CONTINUE TO BE AN ISSUE AND ARE HAVING DIFFICULTY WITH
SPLIT FLOW PATTERN. ECMWF HAS NORTHERN SPLIT COMING SOUTHWARD DOWN
THE COAST AND THEN MERGING WITH ANOTHER PACIFIC LOW FRIDAY AND
SATURDAY. THIS WOULD BRING PRECIPITATION TO MUCH OF THE AREA...WITH
AROUND A HALF INCH IN THE SIERRA. THE 18Z GFS IS SHOWING THE
NORTHERN CUTOFF BRUSHING BY TO THE NORTH AND MOVING EASTWARD OUT OF
THE AREA...WITH THE PACIFIC LOW STAYING WELL OFF THE COAST. THIS IS
A CHANGE FROM THE 12Z RUN WHICH WAS CLOSER TO THE ECMWF. GFS
ENSEMBLES SHOW A WIDE RANGE...WITH MUCH LIGHTER PRECIPITATION OVER A
SMALLER AREA. DUE TO THE UNCERTAINTY OF THIS UNSETTLED
PATTERN...WILL CONTINUE A BROADBRUSH SLIGHT CHANCE OF PRECIPITATION
THROUGH THE EXTENDED PERIOD. HIGH TEMPERATURES LOOK TO COOL TO NEAR
TO SLIGHTLY BELOW NORMAL BY THE WEEKEND.
&&
.AVIATION...
UPR HI CNTRD OVR INTRMTRGN WL SLOLY WKN AND MOV E AS PAC TROF APCHS
CAL CST. SLY FLOW ALF OVR NORCAL. VFR CONDS OVR INTR NORCAL NXT 24
HRS EXC AREAS MVFR IN BR IN CNTRL VLY BTWN 09Z-19Z WITH ISOLD IFR
POSS IN NRN SAN JOAQUIN VLY BTWN 11Z-16Z. ISOLD NE-E SFC WND GUSTS
TO 30 KTS POSS OVR RDGS AND E-W ORIENTED CANYONS OF W SLPS OF
SIERNEV TIL 20Z TUE.
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS66 KSTO 192315
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
330 PM PST MON JAN 19 2009
.DISCUSSION...
FAIR SKIES OVER THE FORECAST AREA THIS AFTERNOON UNDER STRONG UPPER
LEVEL RIDGE OVER THE WEST COAST. WEAK SHORTWAVE TROUGH MOVING INTO
SOCAL SPREADING SOME HIGH CLOUDINESS UP THE SIERRA AT THIS TIME BUT
OTHERWISE HAVING LITTLE IMPACT ON CWA WEATHER WITH TEMPERATURES
RUNNING SIMILAR TO 24 HOURS AGO AND LIKELY TO PUSH WITHIN A DEGREE
OR TWO OF RECORD HIGHS IN A FEW AREAS. MAY SEE JUST A BIT MORE FOG
UP THE CENTRAL VALLEY TONIGHT AS EASTERLY SURFACE GRADIENT OVER
NORCAL WEAKENS ALLOWING FOR A LITTLE LESS MIXING. OTHERWISE...SHOULD
SEE SIMILAR CONDITIONS TONIGHT COMPARED TO LAST NIGHT.
SUBTLE CHANGES IN STORE FOR TUESDAY AS UPPER LEVEL SYSTEM NOW
BETWEEN 130 AND 140 WEST APPROACHES THE COAST. THIS SYSTEM SHOULD
START SPREADING SOME HIGH CLOUDINESS OVER THE REGION AS EARLY AS
TUESDAY AFTERNOON. THIS CLOUDINESS COMBINED WITH SLIGHTLY COOLER
AIRMASS SHOULD BRING SLIGHT DROP IN DAYTIME HIGHS TUESDAY. OFFSHORE
LOW FORECAST BY ALL MODELS TO NUDGE UPPER RIDGE EAST AND BEGIN
MOVING ONTO THE COAST ON WEDNESDAY. GENERAL CONSENSUS IS THAT THIS
SYSTEM WILL SPLIT AS IT COMES INLAND WITH BULK OF ENERGY MOVING INTO
SOUTHERN CALIFORNIA. NORTHERN PORTION OF SPLIT SYSTEM IS FORECAST TO
MOVE INTO NORTHERN CALIFORNIA BRINGING A THREAT OF PRECIPITATION
THERE ALTHOUGH QPF VALUES ARE EXPECTED TO BE RATHER LIGHT. PRECIP
THREAT CONTINUES INTO THURSDAY AS UPPER TROUGH SHIFTS INLAND BUT QPF
VALUES REMAIN LIGHT. DO TO UNCERTAINTY WITH THIS SYSTEM WENT MAINLY
WITH CLIMO POPS INTO THURSDAY WHICH SEEM TO FIT WELL WITH
SURROUNDING OFFICES AND FORECAST THINKING.
.EXTENDED DISCUSSION (FRIDAY THROUGH MONDAY)...
MODEL CHANGES CONTINUE TO BE AN ISSUE AND ARE HAVING DIFFICULTY WITH
SPLIT FLOW PATTERN. ECMWF HAS NORTHERN SPLIT COMING SOUTHWARD DOWN
THE COAST AND THEN MERGING WITH ANOTHER PACIFIC LOW FRIDAY AND
SATURDAY. THIS WOULD BRING PRECIPITATION TO MUCH OF THE AREA...WITH
AROUND A HALF INCH IN THE SIERRA. THE 18Z GFS IS SHOWING THE
NORTHERN CUTOFF BRUSHING BY TO THE NORTH AND MOVING EASTWARD OUT OF
THE AREA...WITH THE PACIFIC LOW STAYING WELL OFF THE COAST. THIS IS
A CHANGE FROM THE 12Z RUN WHICH WAS CLOSER TO THE ECMWF. GFS
ENSEMBLES SHOW A WIDE RANGE...WITH MUCH LIGHTER PRECIPITATION OVER A
SMALLER AREA. DUE TO THE UNCERTAINTY OF THIS UNSETTLED
PATTERN...WILL CONTINUE A BROADBRUSH SLIGHT CHANCE OF PRECIPITATION
THROUGH THE EXTENDED PERIOD. HIGH TEMPERATURES LOOK TO COOL TO NEAR
TO SLIGHTLY BELOW NORMAL BY THE WEEKEND.
&&
.AVIATION...
VFR CONDITIONS WITH LIGHT WINDS EXPECTED OVERNIGHT EXCEPT AREAS OF
MVFR AND ISOLATED IFR CONDITIONS FROM BR AFTER 09Z IN THE VALLEY
FROM KMYV SOUTHWARD. SOME HZ MAY LINGER IN THOSE AREAS MAY LINGER
THROUGH THE DAY. NORTH WINDS WILL KEEP THE NORTHERN SACRAMENTO
VALLEY FREE OF FG/BR.
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS66 KSTO 191756
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
930 AM PST MON JAN 19 2009
.DISCUSSION...
BLOCKING RIDGE BRINGING CLEAR SKIES TO THE FORECAST AREA AGAIN THIS
MORNING. LIGHT NORTHEAST TO SOUTHEAST BREEZE CONTINUES AS SURFACE
HIGH PRESSURE REMAINS OVER THE NORTHERN GREAT BASIN. DRY AIRMASS AND
SLIGHT MIXING AGAIN ALLOWING FOR VERY LITTLE IN THE WAY OF VALLEY
FOG THIS MORNING. SHOULD SEE TEMPERATURES TODAY SIMILAR TO
YESTERDAY. TEMPERATURES RUNNING NEARLY THE SAME AS 24 HOURS AGO SO
MAX TEMPS WITHING A DEGREE OR TWO OF SUNDAY IN CURRENT FORECAST
PACKAGE LOOKS GOOD. UPPER RIDGE FORECAST TO CONTINUE TO SHIFT
EASTWARD ON TUESDAY SO SHOULD SEE A LITTLE COOLING. MAY SEE A LITTLE
MORE VALLEY FOG IN THE MORNING AS SURFACE GRADIENTS WEAKEN. PACIFIC
SYSTEM NOW BETWEEN 130 AND 140 WEST NOW FORECAST BY ALL MODELS TO
NUDGE UPPER RIDGE EAST AND BEGIN MOVING ONTO THE COAST ON WEDNESDAY.
DETAILS DIFFER WITH ECMWF KEEPING THE SYSTEM THE MOST CONSOLIDATED
WITH NAM AND GFS SPLITTING THE SYSTEM A LITTLE MORE WHICH WOULD
BRING A BETTER THREAT OF THE PRECIP AND HIGHER QPF TO SOUTHERN
CALIFORNIA. CHANCE POPS PROBABLY BEST BET FOR NOW WITH POSSIBLY
BIGGER THREAT SOUTHERN ZONES. PRECIP THREAT CONTINUES INTO THURSDAY
AS UPPER TROUGH SHIFTS INLAND.
PACIFIC STORM SYSTEM OUT BY THE DATELINE FORECAST BY MODELS TO SPLIT
AROUND WEDNESDAY WITH SOUTHERN PORTION HEADING INTO THE EASTERN
PACIFIC. MODELS DIVERGE AFTER THAT HOWEVER. ECMWF SPLITS THIS LOW
AGAIN DRAGGING THE NORTHERN PORTION INTO NORCAL FOR A SHOWERY
WEEKEND. NEW 12Z GFS SPLITS THE LOW AS WELL BUT DRAGS MOST OF THE
ENERGY TO THE SOUTHWEST ALLOWING NEXT WEEKEND TO BE MAINLY DRY OVER
NORCAL. NOT SURE THE GFS OPERATIONAL IS VERY TRUSTWORTHY AT THIS
POINT AS THIS SOLUTION IS SO FAR FROM THE ENSEMBLE MEAN. AT ANY
RATE...CONFIDENCE IN NEXT WEEKENDS FORECAST IS LOW AND WILL LIKELY
JUST STICK CLOSE TO CLIMO POPS. SMITH
&&
.AVIATION...
VFR CONDITIONS WILL CONTINUE THROUGH TODAY WITH CLEAR SKIES AND
LIGHT WINDS. LOCAL MVFR IN BR/HZ IN THE SOUTHERN SACRAMENTO AND
NORTHERN SAN JOAQUIN VALLEYS WILL DIMINISH BY LATER THIS MORNING.
EXPECT PATCHY FOG AND AREAS OF BR TO RETURN TO THOSE AREAS BY LATE
EVENING AND CONTINUE OVERNIGHT.
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS66 KSTO 191139
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
340 AM PST MON JAN 19 2009
.DISCUSSION...
VERY STRONG BLOCKING RIDGE HAS MIGRATED A LITTLE FURTHER TO THE EAST
TO OVER THE NORTHERN ROCKIES. WEATHER SYSTEMS APPROACHING 130W
CONTINUE TO WEAKEN AND GET PUSHED ALMOST DUE NORTH INTO NORTHERN
BRITISH COLUMBIA. THIS PATTERN IS EXPECTED TO HOLD FOR ABOUT ANOTHER
24 HOURS GIVING THE REGION ANOTHER COUPLE OF DAYS OF DRY AND VERY
MILD WEATHER AS OFFSHORE GRADIENTS CONTINUE AT THE SURFACE. BY
MID-WEEK...THE RIDGE IS FORECAST TO WEAKEN CONSIDERABLY AS SEVERAL
WEATHER SYSTEMS APPROACH FROM THE WEST. THE INITIAL SYSTEM LATER
WEDNESDAY IS FORECAST TO SPLIT WITH THE MAJORITY OF MODEL SOLUTIONS
TAKING MUCH OF THE ENERGY EITHER TO THE NORTH OR TO THE SOUTH OF THE
FORECAST AREA THOUGH VARIOUS MODEL RUNS HAVE SHOWN DIFFERING
SOLUTIONS...SO WE/LL CONTINUE TO MENTION A SLIGHT CHANCE OF SHOWERS
ACROSS THE REGION FOR THE SECOND HALF OF THE WEEK UNTIL A MORE
REFINED PICTURE EMERGES. ALONG WITH THE SLIGHT CHANCE OF SHOWERS...
THE PATTERN CHANGE WILL BRING A RETURN OF MORE CLOUDINESS ALONG WITH
A COOL DOWN OF TEMPERATURES TO NEAR NORMAL LATE JANUARY LEVELS.
&&
.EXTENDED DISCUSSION (FRIDAY THROUGH MONDAY)...
MODELS INDICATE A LOW OFFSHORE OF THE CALIFORNIA COAST ON FRIDAY AND
ONSHORE ON SATURDAY. THIS SYSTEM MAY BRING A SLIGHT CHANCE OF
PRECIPITATION...ESPECIALLY IF IT TRACKS CLOSER TO THE COAST. THE
MODELS INDICATE A STRONGER SYSTEM COMING DOWN FORM THE NORTH ON
SUNDAY AND INTO MONDAY. ALTHOUGH THE ECMWF IS INDICATING MORE OF AN
INSIDE SLIDER AND THE WETTER GFS HAS STRONGER LOW MOVING DOWN ALONG
THE WEST COAST. THE CURRENT FORECAST OF A SLIGHT CHANCE OF
PRECIPITATION LEANS MORE TOWARDS THE ECMWF. THE GFS ENSEMBLE MEAN IS
CLOSER TO THE ECMWF THAN THE OPERATIONAL GFS. ALTHOUGH THE SPREAD OF
THE ENSEMBLE MEAN IS 130M ON SUNDAY INDICATING UNCERTAINTY WITH A
RANGE OF SOLUTIONS. TEMPERATURES WILL BE NEAR NORMAL FOR THE PERIOD.
&&
.AVIATION...
UPPER LEVEL RIDGE OF HIGH PRESSURE SHIFTS EAST OF THE AREA TODAY.
THIS WILL BRING GENERALLY VFR CONDITIONS EXCEPT AREAS OF MVFR AND
ISOLATED IFR CONDITIONS IN THE VALLEY IN THE MORNING DUE TO
BR/HZ...MAINLY AROUND MARYSVILLE AND SOUTH.
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS66 KSTO 190532
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
930 PM PST SUN JAN 18 2009
.DISCUSSION (UPDATE)...
00Z GFS NOW MORE IN LINE WITH THE ECMWF AS IT SPLITS THE SYSTEM
COMING IN EARLY WEDNESDAY WITH THE SOUTHERN BRANCH MOVING INTO
SOUTHERN CALIFORNIA...AND THE NORTHERN BRANCH SYSTEM WEAKENS AND
SHEARS APART. THE WEDNESDAY / THURSDAY SYSTEM COULD BRING SOME SNOW
SHOWERS TO THE SIERRA MAINLY SOUTH OF I-80 WITH LITTLE PRECIPITATION
EXPECTED FOR SACRAMENTO. THE GFS BRINGS A STRONGER NORTHERN BRANCH
SYSTEM TOWARD THE COAST FRIDAY AND PHASES IT WITH A VERY COLD UPPER
LOW THAT DROPS DOWN THE COAST SUNDAY. PREFER THE ECMWF SOLUTION
WHICH BRINGS ANOTHER SPLITTING SHORT WAVE THROUGH CALIFORNIA
SATURDAY AND DELAYS THE DEVELOPMENT OF A PERSISTENT WEST COAST TROF
UNTIL WE GET CLOSER TO THE END OF THE MONTH. THE GOOD NEWS IS THAT
IS DOES APPEAR A PERSISTENT WEST COAST TROF WILL DEVELOP EVENTUALLY.
WE WILL HAVE A LOT OF GROUND TO MAKE UP IN FEBRUARY AND WE CAN HOPE
THAT INCREASING WESTERLIES ALONG THE EQUATORIAL PACIFIC CAN ENTRAIN
SOME TROPICAL MOISTURE INTO THE TROF FOR BETTER PRECIPITATION
EVENTS. SG
.PREVIOUS DISCUSSION (ISSUED 3:30 PM SUNDAY AFTERNOON)...CLEAR SKIES
OVER THE FORECAST AREA THIS AFTERNOON AS STRONG UPPER RIDGE AXIS
CROSSES OVER THE FORECAST AREA. EVEN FOG AND HAZE THAT HAS PERSISTED
OVER THE SAN JOAQUIN VALLEY THE LAST COUPLE OF AFTERNOONS HAS
CLEARED TODAY. WEAK UPPER LOW OFF THE BAY AREA COAST IS WASHING OUT
UNDER THE SUBSIDENCE OF THE UPPER HIGH AND NOW BECOMING DIFFICULT TO
FIND EVEN ON WATER VAPOR IMAGERY. EXCEPT FOR THE HIGHEST ELEVATIONS
OF THE SIERRA...MOST LOCATIONS SHOWING A SLIGHT INCREASE IN
TEMPERATURE THIS AFTERNOON OVER 24 HOURS AGO. LIGHT NORTHERLY
BREEZES CONTINUE IN THE NORTHERN SACRAMENTO VALLEY DUE TO A SURFACE
HIGH NOW DROPPING INTO THE GREAT BASIN. THESE LIGHT NORTHERLY WINDS
WILL BRING ADIABATIC HEATING TO THE NORTHERN SACRAMENTO VALLEY WHERE
TEMPERATURES ARE LIKELY TO TOP YESTERDAYS VALUES BY SEVERAL DEGREES.
THE SURFACE HIGH IS EXPECTED TO MOVE LITTLE OVER THE NEXT 24 HOURS
SO EXPECT LIGHT NORTH TO EAST BREEZES TO RETURN TONIGHT. THIS SHOULD
KEEP VALLEY FOG TO A MINIMUM.
LITTLE CHANGE IN UNSEASONABLY WARM WEATHER PATTERN EXPECTED OVER THE
NEXT COUPLE OF DAYS AS STRONG UPPER RIDGE SHIFTS FROM CURRENT
POSITION OVER THE WEST COAST SLOWLY EASTWARD TO OVER THE GREAT BASIN
BY TUESDAY. ABOUT ONLY CHANGE WILL BE A CONTINUED SLIGHT COOLING
TREND AND OCCASIONAL HIGH CLOUDINESS. THE HIGH CLOUDINESS WILL
SIGNIFY A CHANGE IN THE OVERALL WEATHER PATTERN BY MID WEEK ALTHOUGH
MID RANGE MODELS HAVING A DIFFICULT TIME FIGURING OUT JUST HOW THIS
CHANGE IS GOING TO OCCUR. GENERAL CONSENSUS NOW IS THAT TROUGH OF
LOW PRESSURE NOW APPROACHING 140 WEST WILL SPLIT AS IT ENCOUNTERS
THE WEST COAST RIDGE WITH THE SOUTHERN PORTION LEAVING SOME SORT OF
LOW PRESSURE SYSTEM OFF THE SOUTHERN CALIFORNIA COAST BY WEDNESDAY
AFTERNOON. GFS HAVING AN ESPECIALLY DIFFICULT TIME AND WITH THIS
SYSTEM AND LATEST 18Z RUN BRINGS IN SYSTEM FARTHER NORTH THAN 12Z
RUN WHICH WOULD BRING PRECIP FARTHER NORTH ON WEDNESDAY POSSIBLY
AFFECT ENTIRE CWA. ECMWF HAS BEEN MORE CONSISTENT DIGGING THE LOW
FARTHER SOUTH AND HAVE MORE CONFIDENCE IN THIS SOLUTION FOR
WEDNESDAY. THEREFORE SLIGHT PRECIP THREAT FOR WEDNESDAY LOOKS GOOD
FOR NOW.
.EXTENDED DISCUSSION (WEDNESDAY NIGHT THROUGH SUNDAY)...FRUSTRATION
WITH THE EXTENDED MODELS CONTINUES...EVEN THOUGH THEY ARE STARTING
TO TREND MORE SIMILARLY. AT THIS TIME....THE GFS AND THE CANADIAN
HAVE STARTED TO ALIGN WITH THE ECMWF AND THE UKMET FOR WEDNESDAY
NIGHT AND THURSDAY...BY ELONGATING AND SPLITTING THE TROUGH AND THEN
TAKING THE BRUNT OF THE MOISTURE AND ENERGY INTO SOUTHERN
CALIFORNIA. HOWEVER...ALL MODELS ARE STRUGGLING WITH THE PLACEMENT
OF WHERE TO BRING THIS SYSTEM INLAND ALONG THE COAST...WHICH IS
IMPACTING HOW FAR NORTH TO BRING PRECIPITATION. FOR NOW WILL KEEP A
SLIGHT CHANCE OF SHOWERS MAINLY OVER THE MOUNTAINS AND THE SOUTHERN
PORTION OF THE CWA...BUT NOT CONFIDENT THAT THIS WILL HAPPEN. THIS
SYSTEM WILL OPEN THE DOOR THOUGH FOR ANOTHER SYSTEM TO APPROACH AND
LINGER OVER THE CALIFORNIA COAST SOME TIME BETWEEN FRIDAY AND
SUNDAY. THE 12Z RUNS THIS MORNING ARE SHOWING MORE MOISTURE WITH
THIS LATTER SYSTEM...AND KEEPING IT FAR ENOUGH NORTH THAT WE MAY SEE
SOMETHING. HOWEVER...CONFIDENCE IS STILL LOW...JUST BECAUSE THE RUN
TO RUN VARIABILITY HAS NOT BEEN CONSISTENT. THEREFORE...WILL KEEP A
SLIGHT CHANCE OF SHOWERS GOING THROUGH SATURDAY...WHICH MAY CARRY
OVER INTO SUNDAY AS WELL. PALMER
&&
.AVIATION...HIGH PRESSURE WILL GRADUALLY SHIFT EAST OVER THE NEXT 24
HOURS...BRINGING PREDOMINATELY VFR CONDITIONS TO NORTHERN
CALIFORNIA. AREAS OF MVFR VISIBILITIES IN HAZY OR MIST WILL
BE POSSIBLE FROM KMYV SOUTHWARD...WITH LOCAL IFR CONDITIONS POSSIBLE
IN THE NORTHERN SAN JOAQUIN VALLEY. LOCALLY GUSTY NE-E WINDS UP TO
35 KTS WILL BE POSSIBLE OVER THE HIGHER ELEVATIONS OF THE NORTHERN
SIERRA AND THROUGH FAVORED ORIENTED CANYONS AND PASSES LATE TONIGHT
AND EARLY TOMORROW MORNING.
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS66 KSTO 190531
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
930 PM PST SUN JAN 18 2009
.DISCUSSION (UPDATE)...
00Z GFS NOW MORE IN LINE WITH THE ECMWF AS IT SPLITS THE SYSTEM
COMING IN EARLY WEDNESDAY WITH THE SOUTHERN BRANCH MOVING INTO
SOUTHERN CALIFORNIA...AND THE NORTHERN BRANCH SYSTEM WEAKENS AND
SHEARS APART. THE WEDNESDAY / THURSDAY SYSTEM COULD BRING SOME SNOW
SHOWERS TO THE SIERRA MAINLY SOUTH OF I-80 WITH LITTLE PRECIPITATION
EXPECTED FOR SACRAMENTO. THE GFS BRINGS A STRONGER NORTHERN BRANCH
SYSTEM TOWARD THE COAST FRIDAY AND PHASES IT WITH A VERY COLD UPPER
LOW THAT DROPS DOWN THE COAST SUNDAY. PREFER THE ECMWF SOLUTION
WHICH BRINGS ANOTHER SPLITTING SHORT WAVE THROUGH CALIFORNIA
SATURDAY AND DELAYS THE DEVELOPMENT OF A PERSISTENT WEST COAST TROF
TOWARD THE END OF THE MONTH. THE GOOD NEWS IS THAT IS DOES APPEAR A
PERSISTENT WEST COAST TROF WILL DEVELOP EVENTUALLY...BUT WE WILL
HAVE A LOT OF GROUND TO MAKE UP IN FEBRUARY AND WE HOPE THAT
INCREASING WESTERLIES ALONG THE EQUATORIAL PACIFIC CAN ENTRAIN SOME
TROPICAL MOISTURE INTO THE TROF. SG
.PREVIOUS DISCUSSION (ISSUED 3:30 PM SUNDAY AFTERNOON)...CLEAR SKIES
OVER THE FORECAST AREA THIS AFTERNOON AS STRONG UPPER RIDGE AXIS
CROSSES OVER THE FORECAST AREA. EVEN FOG AND HAZE THAT HAS PERSISTED
OVER THE SAN JOAQUIN VALLEY THE LAST COUPLE OF AFTERNOONS HAS
CLEARED TODAY. WEAK UPPER LOW OFF THE BAY AREA COAST IS WASHING OUT
UNDER THE SUBSIDENCE OF THE UPPER HIGH AND NOW BECOMING DIFFICULT TO
FIND EVEN ON WATER VAPOR IMAGERY. EXCEPT FOR THE HIGHEST ELEVATIONS
OF THE SIERRA...MOST LOCATIONS SHOWING A SLIGHT INCREASE IN
TEMPERATURE THIS AFTERNOON OVER 24 HOURS AGO. LIGHT NORTHERLY
BREEZES CONTINUE IN THE NORTHERN SACRAMENTO VALLEY DUE TO A SURFACE
HIGH NOW DROPPING INTO THE GREAT BASIN. THESE LIGHT NORTHERLY WINDS
WILL BRING ADIABATIC HEATING TO THE NORTHERN SACRAMENTO VALLEY WHERE
TEMPERATURES ARE LIKELY TO TOP YESTERDAYS VALUES BY SEVERAL DEGREES.
THE SURFACE HIGH IS EXPECTED TO MOVE LITTLE OVER THE NEXT 24 HOURS
SO EXPECT LIGHT NORTH TO EAST BREEZES TO RETURN TONIGHT. THIS SHOULD
KEEP VALLEY FOG TO A MINIMUM.
LITTLE CHANGE IN UNSEASONABLY WARM WEATHER PATTERN EXPECTED OVER THE
NEXT COUPLE OF DAYS AS STRONG UPPER RIDGE SHIFTS FROM CURRENT
POSITION OVER THE WEST COAST SLOWLY EASTWARD TO OVER THE GREAT BASIN
BY TUESDAY. ABOUT ONLY CHANGE WILL BE A CONTINUED SLIGHT COOLING
TREND AND OCCASIONAL HIGH CLOUDINESS. THE HIGH CLOUDINESS WILL
SIGNIFY A CHANGE IN THE OVERALL WEATHER PATTERN BY MID WEEK ALTHOUGH
MID RANGE MODELS HAVING A DIFFICULT TIME FIGURING OUT JUST HOW THIS
CHANGE IS GOING TO OCCUR. GENERAL CONSENSUS NOW IS THAT TROUGH OF
LOW PRESSURE NOW APPROACHING 140 WEST WILL SPLIT AS IT ENCOUNTERS
THE WEST COAST RIDGE WITH THE SOUTHERN PORTION LEAVING SOME SORT OF
LOW PRESSURE SYSTEM OFF THE SOUTHERN CALIFORNIA COAST BY WEDNESDAY
AFTERNOON. GFS HAVING AN ESPECIALLY DIFFICULT TIME AND WITH THIS
SYSTEM AND LATEST 18Z RUN BRINGS IN SYSTEM FARTHER NORTH THAN 12Z
RUN WHICH WOULD BRING PRECIP FARTHER NORTH ON WEDNESDAY POSSIBLY
AFFECT ENTIRE CWA. ECMWF HAS BEEN MORE CONSISTENT DIGGING THE LOW
FARTHER SOUTH AND HAVE MORE CONFIDENCE IN THIS SOLUTION FOR
WEDNESDAY. THEREFORE SLIGHT PRECIP THREAT FOR WEDNESDAY LOOKS GOOD
FOR NOW.
.EXTENDED DISCUSSION (WEDNESDAY NIGHT THROUGH SUNDAY)...FRUSTRATION
WITH THE EXTENDED MODELS CONTINUES...EVEN THOUGH THEY ARE STARTING
TO TREND MORE SIMILARLY. AT THIS TIME....THE GFS AND THE CANADIAN
HAVE STARTED TO ALIGN WITH THE ECMWF AND THE UKMET FOR WEDNESDAY
NIGHT AND THURSDAY...BY ELONGATING AND SPLITTING THE TROUGH AND THEN
TAKING THE BRUNT OF THE MOISTURE AND ENERGY INTO SOUTHERN
CALIFORNIA. HOWEVER...ALL MODELS ARE STRUGGLING WITH THE PLACEMENT
OF WHERE TO BRING THIS SYSTEM INLAND ALONG THE COAST...WHICH IS
IMPACTING HOW FAR NORTH TO BRING PRECIPITATION. FOR NOW WILL KEEP A
SLIGHT CHANCE OF SHOWERS MAINLY OVER THE MOUNTAINS AND THE SOUTHERN
PORTION OF THE CWA...BUT NOT CONFIDENT THAT THIS WILL HAPPEN. THIS
SYSTEM WILL OPEN THE DOOR THOUGH FOR ANOTHER SYSTEM TO APPROACH AND
LINGER OVER THE CALIFORNIA COAST SOME TIME BETWEEN FRIDAY AND
SUNDAY. THE 12Z RUNS THIS MORNING ARE SHOWING MORE MOISTURE WITH
THIS LATTER SYSTEM...AND KEEPING IT FAR ENOUGH NORTH THAT WE MAY SEE
SOMETHING. HOWEVER...CONFIDENCE IS STILL LOW...JUST BECAUSE THE RUN
TO RUN VARIABILITY HAS NOT BEEN CONSISTENT. THEREFORE...WILL KEEP A
SLIGHT CHANCE OF SHOWERS GOING THROUGH SATURDAY...WHICH MAY CARRY
OVER INTO SUNDAY AS WELL. PALMER
&&
.AVIATION...HIGH PRESSURE WILL GRADUALLY SHIFT EAST OVER THE NEXT 24
HOURS...BRINGING PREDOMINATELY VFR CONDITIONS TO NORTHERN
CALIFORNIA. AREAS OF MVFR VISIBILITIES IN HAZY OR MIST WILL
BE POSSIBLE FROM KMYV SOUTHWARD...WITH LOCAL IFR CONDITIONS POSSIBLE
IN THE NORTHERN SAN JOAQUIN VALLEY. LOCALLY GUSTY NE-E WINDS UP TO
35 KTS WILL BE POSSIBLE OVER THE HIGHER ELEVATIONS OF THE NORTHERN
SIERRA AND THROUGH FAVORED ORIENTED CANYONS AND PASSES LATE TONIGHT
AND EARLY TOMORROW MORNING.
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS66 KSTO 182312
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
330 PM PST SUN JAN 18 2009
.DISCUSSION...CLEAR SKIES OVER THE FORECAST AREA THIS AFTERNOON AS
STRONG UPPER RIDGE AXIS CROSSES OVER THE FORECAST AREA. EVEN FOG AND
HAZE THAT HAS PERSISTED OVER THE SAN JOAQUIN VALLEY THE LAST COUPLE
OF AFTERNOONS HAS CLEARED TODAY. WEAK UPPER LOW OFF THE BAY AREA
COAST IS WASHING OUT UNDER THE SUBSIDENCE OF THE UPPER HIGH AND NOW
BECOMING DIFFICULT TO FIND EVEN ON WATER VAPOR IMAGERY. EXCEPT FOR
THE HIGHEST ELEVATIONS OF THE SIERRA...MOST LOCATIONS SHOWING A
SLIGHT INCREASE IN TEMPERATURE THIS AFTERNOON OVER 24 HOURS AGO.
LIGHT NORTHERLY BREEZES CONTINUE IN THE NORTHERN SACRAMENTO VALLEY
DUE TO A SURFACE HIGH NOW DROPPING INTO THE GREAT BASIN. THESE LIGHT
NORTHERLY WINDS WILL BRING ADIABATIC HEATING TO THE NORTHERN
SACRAMENTO VALLEY WHERE TEMPERATURES ARE LIKELY TO TOP YESTERDAYS
VALUES BY SEVERAL DEGREES. THE SURFACE HIGH IS EXPECTED TO MOVE
LITTLE OVER THE NEXT 24 HOURS SO EXPECT LIGHT NORTH TO EAST BREEZES
TO RETURN TONIGHT. THIS SHOULD KEEP VALLEY FOG TO A MINIMUM.
LITTLE CHANGE IN UNSEASONABLY WARM WEATHER PATTERN EXPECTED OVER THE
NEXT COUPLE OF DAYS AS STRONG UPPER RIDGE SHIFTS FROM CURRENT
POSITION OVER THE WEST COAST SLOWLY EASTWARD TO OVER THE GREAT BASIN
BY TUESDAY. ABOUT ONLY CHANGE WILL BE A CONTINUED SLIGHT COOLING
TREND AND OCCASIONAL HIGH CLOUDINESS. THE HIGH CLOUDINESS WILL
SIGNIFY A CHANGE IN THE OVERALL WEATHER PATTERN BY MID WEEK ALTHOUGH
MID RANGE MODELS HAVING A DIFFICULT TIME FIGURING OUT JUST HOW THIS
CHANGE IS GOING TO OCCUR. GENERAL CONSENSUS NOW IS THAT TROUGH OF
LOW PRESSURE NOW APPROACHING 140 WEST WILL SPLIT AS IT ENCOUNTERS
THE WEST COAST RIDGE WITH THE SOUTHERN PORTION LEAVING SOME SORT OF
LOW PRESSURE SYSTEM OFF THE SOUTHERN CALIFORNIA COAST BY WEDNESDAY
AFTERNOON. GFS HAVING AN ESPECIALLY DIFFICULT TIME AND WITH THIS
SYSTEM AND LATEST 18Z RUN BRINGS IN SYSTEM FARTHER NORTH THAN 12Z
RUN WHICH WOULD BRING PRECIP FARTHER NORTH ON WEDNESDAY POSSIBLY
AFFECT ENTIRE CWA. ECMWF HAS BEEN MORE CONSISTENT DIGGING THE LOW
FARTHER SOUTH AND HAVE MORE CONFIDENCE IN THIS SOLUTION FOR
WEDNESDAY. THEREFORE SLIGHT PRECIP THREAT FOR WEDNESDAY LOOKS GOOD
FOR NOW.
.EXTENDED DISCUSSION (WEDNESDAY NIGHT THROUGH SUNDAY)...FRUSTRATION
WITH THE EXTENDED MODELS CONTINUES...EVEN THOUGH THEY ARE STARTING
TO TREND MORE SIMILARLY. AT THIS TIME....THE GFS AND THE CANADIAN
HAVE STARTED TO ALIGN WITH THE ECMWF AND THE UKMET FOR WEDNESDAY
NIGHT AND THURSDAY...BY ELONGATING AND SPLITTING THE TROUGH AND THEN
TAKING THE BRUNT OF THE MOISTURE AND ENERGY INTO SOUTHERN
CALIFORNIA. HOWEVER...ALL MODELS ARE STRUGGLING WITH THE PLACEMENT
OF WHERE TO BRING THIS SYSTEM INLAND ALONG THE COAST...WHICH IS
IMPACTING HOW FAR NORTH TO BRING PRECIPITATION. FOR NOW WILL KEEP A
SLIGHT CHANCE OF SHOWERS MAINLY OVER THE MOUNTAINS AND THE SOUTHERN
PORTION OF THE CWA...BUT NOT CONFIDENT THAT THIS WILL HAPPEN. THIS
SYSTEM WILL OPEN THE DOOR THOUGH FOR ANOTHER SYSTEM TO APPROACH AND
LINGER OVER THE CALIFORNIA COAST SOME TIME BETWEEN FRIDAY AND
SUNDAY. THE 12Z RUNS THIS MORNING ARE SHOWING MORE MOISTURE WITH
THIS LATTER SYSTEM...AND KEEPING IT FAR ENOUGH NORTH THAT WE MAY SEE
SOMETHING. HOWEVER...CONFIDENCE IS STILL LOW...JUST BECAUSE THE RUN
TO RUN VARIABILITY HAS NOT BEEN CONSISTENT. THEREFORE...WILL KEEP A
SLIGHT CHANCE OF SHOWERS GOING THROUGH SATURDAY...WHICH MAY CARRY
OVER INTO SUNDAY AS WELL. PALMER
&&
.AVIATION...HIGH PRESSURE WILL GRADUALLY SHIFT EAST OVER THE NEXT 24
HOURS...BRINGING PREDOMINATELY VFR CONDITIONS TO NORTHERN
CALIFORNIA. HOWEVER...AREAS OF MVFR VISIBILITIES IN HAZY OR MIST
WILL BE POSSIBLE FROM KMYV SOUTHWARD...WITH LOCAL IFR CONDITIONS
POSSIBLE IN THE NORTHERN SAN JOAQUIN VALLEY. LOCALLY GUSTY NE-E
WINDS UP TO 35 KTS WILL BE POSSIBLE OVER THE HIGHER ELEVATIONS OF
THE NORTHERN SIERRA AND THROUGH FAVORED ORIENTED CANYONS AND PASSES
LATE TONIGHT AND EARLY TOMORROW MORNING.
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS66 KSTO 182311 AAA
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
330 PM PST SUN JAN 18 2009
.DISCUSSION...CLEAR SKIES OVER THE FORECAST AREA THIS AFTERNOON AS
STRONG UPPER RIDGE AXIS CROSSES OVER THE FORECAST AREA. EVEN FOG AND
HAZE THAT HAS PERSISTED OVER THE SAN JOAQUIN VALLEY THE LAST COUPLE
OF AFTERNOONS HAS CLEARED TODAY. WEAK UPPER LOW OFF THE BAY AREA
COAST IS WASHING OUT UNDER THE SUBSIDENCE OF THE UPPER HIGH AND NOW
BECOMING DIFFICULT TO FIND EVEN ON WATER VAPOR IMAGERY. EXCEPT FOR
THE HIGHEST ELEVATIONS OF THE SIERRA...MOST LOCATIONS SHOWING A
SLIGHT INCREASE IN TEMPERATURE THIS AFTERNOON OVER 24 HOURS AGO.
LIGHT NORTHERLY BREEZES CONTINUE IN THE NORTHERN SACRAMENTO VALLEY
DUE TO A SURFACE HIGH NOW DROPPING INTO THE GREAT BASIN. THESE LIGHT
NORTHERLY WINDS WILL BRING ADIABATIC HEATING TO THE NORTHERN
SACRAMENTO VALLEY WHERE TEMPERATURES ARE LIKELY TO TOP YESTERDAYS
VALUES BY SEVERAL DEGREES. THE SURFACE HIGH IS EXPECTED TO MOVE
LITTLE OVER THE NEXT 24 HOURS SO EXPECT LIGHT NORTH TO EAST BREEZES
TO RETURN TONIGHT. THIS SHOULD KEEP VALLEY FOG TO A MINIMUM.
LITTLE CHANGE IN UNSEASONABLY WARM WEATHER PATTERN EXPECTED OVER THE
NEXT COUPLE OF DAYS AS STRONG UPPER RIDGE SHIFTS FROM CURRENT
POSITION OVER THE WEST COAST SLOWLY EASTWARD TO OVER THE GREAT BASIN
BY TUESDAY. ABOUT ONLY CHANGE WILL BE A CONTINUED SLIGHT COOLING
TREND AND OCCASIONAL HIGH CLOUDINESS. THE HIGH CLOUDINESS WILL
SIGNIFY A CHANGE IN THE OVERALL WEATHER PATTERN BY MID WEEK ALTHOUGH
MID RANGE MODELS HAVING A DIFFICULT TIME FIGURING OUT JUST HOW THIS
CHANGE IS GOING TO OCCUR. GENERAL CONSENSUS NOW IS THAT TROUGH OF
LOW PRESSURE NOW APPROACHING 140 WEST WILL SPLIT AS IT ENCOUNTERS
THE WEST COAST RIDGE WITH THE SOUTHERN PORTION LEAVING SOME SORT OF
LOW PRESSURE SYSTEM OFF THE SOUTHERN CALIFORNIA COAST BY WEDNESDAY
AFTERNOON. GFS HAVING AN ESPECIALLY DIFFICULT TIME AND WITH THIS
SYSTEM AND LATEST 18Z RUN BRINGS IN SYSTEM FARTHER NORTH THAN 12Z
RUN WHICH WOULD BRING PRECIP FARTHER NORTH ON WEDNESDAY POSSIBLY
AFFECT ENTIRE CWA. ECMWF HAS BEEN MORE CONSISTENT DIGGING THE LOW
FARTHER SOUTH AND HAVE MORE CONFIDENCE IN THIS SOLUTION FOR
WEDNESDAY. THEREFORE SLIGHT PRECIP THREAT FOR WEDNESDAY LOOKS GOOD
FOR NOW.
.EXTENDED DISCUSSION (WEDNESDAY NIGHT THROUGH SUNDAY)...FRUSTRATION
WITH THE EXTENDED MODELS CONTINUES...EVEN THOUGH THEY ARE STARTING
TO TREND MORE SIMILARLY. AT THIS TIME....THE GFS AND THE CANADIAN
HAVE STARTED TO ALIGN WITH THE ECMWF AND THE UKMET FOR WEDNESDAY
NIGHT AND THURSDAY...BY ELONGATING AND SPLITTING THE TROUGH AND THEN
TAKING THE BRUNT OF THE MOISTURE AND ENERGY INTO SOUTHERN
CALIFORNIA. HOWEVER...ALL MODELS ARE STRUGGLING WITH THE PLACEMENT
OF WHERE TO BRING THIS SYSTEM INLAND ALONG THE COAST...WHICH IS
IMPACTING HOW FAR NORTH TO BRING PRECIPITATION. FOR NOW WILL KEEP A
SLIGHT CHANCE OF SHOWERS MAINLY OVER THE MOUNTAINS AND THE SOUTHERN
PORTION OF THE CWA...BUT NOT CONFIDENT THAT THIS WILL HAPPEN. THIS
SYSTEM WILL OPEN THE DOOR THOUGH FOR ANOTHER SYSTEM TO APPROACH AND
LINGER OVER THE CALIFORNIA COAST SOME TIME BETWEEN FRIDAY AND
SUNDAY. THE 12Z RUNS THIS MORNING ARE SHOWING MORE MOISTURE WITH
THIS LATTER SYSTEM...AND KEEPING IT FAR ENOUGH NORTH THAT WE MAY SEE
SOMETHING. HOWEVER...CONFIDENCE IS STILL LOW...JUST BECAUSE THE RUN
TO RUN VARIABILITY HAS NOT BEEN CONSISTENT. THEREFORE...WILL KEEP A
SLIGHT CHANCE OF SHOWERS GOING THROUGH SATURDAY...WHICH MAY CARRY
OVER INTO SUNDAY AS WELL. PALMER
&&
.AVIATION...HIGH PRESSURE WILL GRADUALLY SHIFT EAST OVER THE NEXT 24
HOURS...BRINGING PREDOMINATELY VFR CONDITIONS TO NORTHERN
CALIFORNIA. HOWEVER...AREAS OF MVFR VISIBILITIES IN HAZY OR MIST
WILL BE POSSIBLE FROM KMYV SOUTHWARD...WITH LOCAL IFR CONDITIONS
POSSIBLE IN THE NORTHERN SAN JOAQUIN VALLEY. LOCALLY GUSTY NE-E
WINDS UP TO 35 KTS WILL BE POSSIBLE OVER THE HIGHER ELEVATIONS OF
THE NORTHERN SIERRA AND THROUGH FAVORED ORIENTED CANYONS AND PASSES
LATE TONIGHT AND EARLY TOMORROW MORNING.
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS66 KSTO 181733 AAA
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
930 AM PST SUN JAN 18 2009
.DISCUSSION...
NEARLY CLEAR SKIES OVER THE CWA THIS MORNING UNDER STRONG HIGH
PRESSURE REX BLOCK PATTERN WITH RIDGE EXTENDING UP INTO THE YUKON
AND VERY WEAK LOW CENTERED NEAR THE SAN FRANCISCO BAY AREA COAST.
EVEN THE SAN JOAQUIN VALLEY FOG DID NOT GET THAT DENSE THIS MORNING
WITH MODESTO ONLY DROPPING BRIEFLY BELOW 2 MILES VISIBILITY. WEAK
UPPER LOW BARELY VISIBLE ON IR IMAGERY WITH JUST SOME CIRRUS BEING
PRODUCED IN THE RENO AREA. UPPER LOW IS BRINGING SLIGHTLY COOLER
AIRMASS THIS MORNING PER OAKLAND SOUNDING ABOVE 900 MB AND MOST
MOUNTAIN RAWS AND ASOS SITES REPORTING SLIGHTLY COOLER TEMPERATURES
THAN 24 HOURS AGO. SEVERAL VALLEY LOCATIONS ARE RUNNING SLIGHTLY
WARMER TODAY DUE TO SLIGHTLY STRONGER NORTHERLY BREEZES. THESE
BREEZES WHICH HAVE ALSO HELPED KEEP VALLEY FOG TO A MINIMUM ARE A
RESULT OF SURFACE HIGH PRESSURE IN THE NORTHERN GREAT BASIN. THIS
SURFACE HIGH IS EXPECTED TO MOVE LITTLE OVER THE NEXT 24 HOURS SO
EXPECT BREEZES TO RETURN TONIGHT. ALTHOUGH AIRMASS IS A BIT COOLER
TODAY...WILL LIKELY NOT SEE MUCH IN THE WAY OF COOLING AS UPPER
RIDGE AXIS MOVES OVER THE WEST COAST AND THEREFORE LIKELY NOT SEE
QUITE AS MUCH COOLING AS IN CURRENT FORECAST PACKAGE.
LITTLE CHANGE IN UNSEASONABLY WARM WEATHER PATTERN EXPECTED OVER THE
NEXT COUPLE OF DAYS AS STRONG UPPER RIDGE SHIFTS FROM CURRENT
POSITION OVER THE WEST COAST SLOWLY EASTWARD TO OVER THE GREAT BASIN
BY TUESDAY. ABOUT ONLY CHANGE WILL BE A CONTINUED SLIGHT COOLING
TREND AND OCCASIONAL HIGH CLOUDINESS. THE HIGH CLOUDINESS WILL
SIGNIFY A CHANGE IN THE OVERALL WEATHER PATTERN BY MID WEEK ALTHOUGH
MID TO EXTENDED WEATHER MODELS HAVING A VERY DIFFICULT TIME FIGURING
OUT JUST HOW THIS CHANGE IS GOING TO OCCUR. GENERAL CONSENSUS NOW IS
THAT TROUGH OF LOW PRESSURE NOW APPROACHING 140 WEST WILL SPLIT AS
IT ENCOUNTERS THE WEST COAST RIDGE LEAVING SOME SORT OF LOW PRESSURE
SYSTEM OFF THE SOUTHERN CALIFORNIA COAST BY WEDNESDAY AFTERNOON.
APPEARS THAT THIS LOW WILL MOVE INLAND WELL SOUTH OF THE CWA
BRINGING SOCAL A MUCH BETTER PRECIP THREAT THAN NORCAL BUT WITH
PORTIONS OF THE BROKEN LOW TRACKING THROUGH NORCAL...SLIGHT PRECIP
THREAT IN CURRENT FORECAST FOR THE MOUNTAIN AREAS THURSDAY LOOKS
OKAY FOR NOW.
AFTER THURSDAY...MODELS DIVERGE AND GFS ENSEMBLE MEMBERS INDICATING
A HUGH RANGE OF POSSIBILITIES. COMMONALITY OF ALL EXTENDED MODELS
HOWEVER IS SOME SORT OF SPLIT IN THE WESTERLIES BETWEEN ABOUT 130
AND 140 WEST. ALL EXTENDED MODELS HINT AT SOME SORT OF LOW FORMING
IN THE SOUTHERN BRANCH OF THE WESTERLIES NEAR OR OFF THE CALIFORNIA
COAST BY NEXT WEEKEND BUT DIFFER QUITE A BIT ON POSITION. WITH
SIGNIFICANT UNCERTAINTY IN THIS TIMEFRAME...CLIMO POPS BEST BET FOR
NEXT WEEKEND. SMITH
&&
.AVIATION...
HIGH PRESSURE WILL REMAIN OVER THE WEST COAST THROUGH THE NEXT 24
HOURS...WITH PREDOMINATELY VFR CONDITIONS PREVAILING.
HOWEVER...AREAS OF MVFR VISIBILITIES IN HAZY OR MIST WILL BE
POSSIBLE FROM KMYV SOUTHWARD. LOCALLY GUSTY NE-E WINDS UP TO 35 KTS
WILL BE POSSIBLE OVER THE HIGHER ELEVATIONS OF THE NORTHERN SIERRA
AND THROUGH FAVORED ORIENTED CANYONS AND PASSES THROUGH 21Z.
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS66 KSTO 181244 AAA
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
445 AM PST SUN JAN 18 2009
.DISCUSSION...
STRONG REX BLOCK KEEPING NRN CAL HIGH AND DRY. THIS HAS KEPT NRN
CAL TEMPS WELL ABOVE NORMAL. THE HIGH CENTER WITHIN THE BLOCK HAS
SHIFTED NWD INTO BC AND THE LOW CENTER OVER NRN CAL AS EVIDENT ON
WATER VAPOR. METSAT SHOWS APEX OF RIDGE OVER YUKON AND ERN ALASKA.
THE SLIGHTLY LOWER HGTS HAVE BROUGHT DOWN TEMPS A FEW DEGREES AND WE
WILL SEE A GRADUAL DROP IN TEMPS THRU THE WEEK AS THE BLOCKING RIDGE
SHIFTS EWD...BUT STILL AT OR ABOVE NORMAL.
18/06Z GFS NOW REVERTS CLOSE TO THE 17/18Z RUN WITH MORE OF A
SPLITTING AND LESS PROGRESSIVE SYSTEM. THIS IS MORE IN LINE WITH
WHAT THE PAST FEW RUNS OF THE ECMWF AND GEM HAVE BEEN ILLUSTRATING.
THIS SPLITTING SYSTEM LOOKS TO BRING MORE OF A POTENTIAL OF PRECIP
TO SRN CAL THAN OUR AREA. LATEST HPC MODEL DIAGNOSTIC DISCUSSION
ALSO FAVORS THE SLOWER SOLUTIONS OF THE ECMWF AND GEM. GFS IS A BIT
TOO QUICK TO BREAKDOWN THE STABLE HIGH AMPLITUDE PATTERN. AS THIS
PATTERN BECOMES INCREASINGLY AMPLIFIED...THE JET BECOMES MORE
FRACTURED UPSTREAM. SO WITH A SPLITTING AND WEAKENING TROUGH
APPROACHING CAL LATE WED...OUR SRN AREAS MAY SEE A SLIGHT CHANCE OF
PRECIP WED NIGHT. WEAK TRANSITORY RIDGING BUILDS IN THU BEFORE THE
NEXT TROUGH IMPACTS THE AREA FRI WITH ONLY A SLIGHT CHANCE OF
PRECIP. AGAIN THE GFS AND EVEN THE GEM ARE MORE PROGRESSIVE THAN
THE ECMWF FOR FRI. THE ECMWF IS LESS PROGRESSIVE AND THE TROUGH
CUTS OFF NEAR 33N 135W. SO KEPT A SLIGHT CHANCE OF PRECIP OVER THE
WEEKEND WITH THE UNCERTAINTY OF THE PATTERN.
JCLAPP
&&
.AVIATION...
HI PRES ALG THE W CST WL CONT VFR CONDS ACRS THE RGN NXT 24 HRS XCP
FOR WDSPRD MVFR VSBYS IN BR/HZ IN THE CNTL VLY FM VCNTY KSAC SWD.
LCL IFR VSBYS PSBL THRU 17Z IN THE SAC METRO AREA SWD INTO THE NRN
SJ VLY. LCL GUSTY ELY WINDS 20-30 KTS PSBL MAINLY THRU 20Z HYR ELEVS
NRN SIERNEV AND ALG W FACING CANYONS ON THE W SLPS.
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS66 KSTO 180533 AAA
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
930 PM PST SAT JAN 17 2009
.DISCUSSION...
.UPDATE...
00Z GFS CONTINUES TO BRING A STRONGER NORTHERN BRANCH SYSTEM INTO
CALIFORNIA WEDNESDAY WHILE THE ECMWF HANGS ONTO THE IDEA OF A
SPLITTING SYSTEM THAT BRINGS MORE PRECIPITATION TO SOUTHERN
CALIFORNIA THAN OUR AREA. 00Z CANADIAN STILL HINTS AT A TAP INTO
SOME SUBTROPICAL MOISTURE OFF THE BAJA COAST THURSDAY BEFORE A
DECENT SYSTEM TREKS INTO NORTHERN CALIFORNIA THURSDAY NIGHT AND
FRIDAY. WHEN THE MODELS ARE ALL OVER THE PLACE LIKE THIS A
SIGNIFICANT PATTERN CHANGE MAY BE ON TAP. THE MODELS CAN BE TOO FAST
BREAKING DOWN STRONG WEST COAST RIDGE / EASTERN U.S. TROF
PATTERNS...THE SST WARM WATER ANOMALY NORTH OF HAWAII AND A WEAK LA
NINA CONDITION SUPPORTS THE RIDGE RETROGRADING WESTWARD IN THE NEXT
WEEK OR TWO...AND WE WILL HOPE THAT THE ADJUSTMENT WAVES MOVING INTO
THE WEST COAST CAN TAP INTO SOME BETTER MOISTURE. SG
.PREVIOUS DISCUSSION (ISSUED 3:30 PM SATURDAY)...
STILL SOME LIGHT FOG IN THE NORTHERN SAN JOAQUIN AND SOUTHERN SAC
VALLEY THIS AFTERNOON...OTHERWISE SKIES ARE CLEAR UNDER STRONG UPPER
LEVEL RIDGE. NORTHEASTERLY SURFACE GRADIENTS HAVE WEAKENED SLIGHTLY
AND AS A RESULT...WINDS ARE FAIRLY LIGHT MOST AREAS. AIRMASS RUNNING
JUST A LITTLE COOLER TODAY AND TEMPERATURES RUNNING A LITTLE COOLER
MOST AREAS. TEMPERATURES ARE MUCH COOLER...NEARLY TEN DEGREES...IN
THE NORTHERN SACRAMENTO VALLEY DUE TO THE LACK OF LIGHT NORTHERLY
WINDS WHICH BROUGHT ADIABATIC WARMING ON FRIDAY. AS SURFACE HIGH
OVER THE PACIFIC NORTHWEST DIGS SOUTHWARD INTO GREAT
BASIN...NORTHEAST TO EAST SURFACE GRADIENT INCREASES A BIT TONIGHT
SO SHOULD SEE BREEZY NORTHEAST WINDS AGAIN OVERNIGHT ESPECIALLY OVER
THE SIERRA FOOTHILLS. THIS SHOULD LIMIT NIGHTTIME FOG TONIGHT TO THE
SOUTHERN SAC VALLEY AND NORTHERN SAN JOAQUIN VLY. UPPER RIDGE
FORECAST TO SHIFT FROM JUST OFFSHORE TO JUST EAST OF THE FORECAST
AREA BY SUNDAY AFTERNOON SO SHOULD SEE A LITTLE MORE COOLING FOR
SECOND HALF OF WEEKEND. ONLY MINOR CHANGES EXPECTED ON MONDAY AS
UPPER PRESSURE PATTERN ONLY SHIFTING SLIGHTLY. CONTINUED SLOW
COOLING TREND CONTINUES AS UPPER RIDGE SHIFTS EAST ON TUESDAY AND
PACIFIC TROUGH APPROACHES THE NORTH COAST.
.EXTENDED DISCUSSION (TUESDAY NIGHT THROUGH SATURDAY)...EXTENDED
MODELS CONTINUE TO STRUGGLE WITH THE TUESDAY NIGHT THROUGH SATURDAY
PERIOD. ALTHOUGH THE 12Z GFS AND CANADIAN ARE BOTH SIMILAR IN
TIMING WITH THE EXTENDED SYSTEMS...THEY SEEMS TO BE BREAKING DOWN
THE CURRENT RIDGE TOO QUICKLY BY BRINGING A SYSTEM INTO THE PACIFIC
NORTHWEST TUESDAY NIGHT AND WEDNESDAY...FOLLOWED BY ANOTHER SYSTEM
ON FRIDAY. MEANWHILE...THE ECMWF AND UKMET ARE SIMILAR AND MORE
CONSISTENT FROM RUN TO RUN...KEEPING A LONGER WAVE TROUGH OFF THE
COAST THROUGH AT LEAST WEDNESDAY...SPLITTING ITS ENERGY AND MOISTURE
AS IT MOVES INLAND SOME TIME WEDNESDAY AND WEDNESDAY NIGHT.
UNFORTUNATELY...IT APPEARS THAT THE BRUNT OF THE MOISTURE WILL THEN
MOVES INTO SOUTHERN CALIFORNIA...LIMITING ANY REAL CHANCE AT SOME
PRECIPITATION OVER NORTHERN CALIFORNIA. A SECONDARY SYSTEM WOULD
THEN MOVE INTO CENTRAL OR SOUTHERN CALIFORNIA SOMETIME FRIDAY NIGHT
AND SATURDAY...ONLY GIVING THE NORTHERN HALF OF THE STATE A GLANCING
CHANCE OF SOME SHOWERS. CONFIDENCE IS LOW IN THESE SOLUTIONS...BUT
TEND TO BELIEVE THE LATTER MODELS SEEM MORE REASONABLE. EITHER WAY
THOUGH... DOUBTFUL THAT NORTHERN CALIFORNIA WILL SEE MUCH OF
ANYTHING...WITH PRIMARILY DRY CONDITIONS AND MORE SEASONAL
TEMPERATURES PREVAILING. DUE TO THE UNCERTAINTY THOUGH....HAVE KEPT
A SLIGHT CHANCE IN THE FORECAST...MAINLY OVER THE HIGHER TERRAIN
THROUGH THE PERIOD. PALMER
&&
.AVIATION...HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH THE
NEXT 24 HOURS...WITH PRIMARILY VFR CONDITIONS PREVAILING. AREAS OF
MVFR VISIBILITIES IN HAZY OR MIST WILL CONTINUE SOUTH OF KMYV WITH
LOCAL IFR/LIFR CONDITIONS POSSIBLY DEVELOPING IN FOG OR MIST
OVERNIGHT. LOCAL NORTHEAST TO EAST WINDS GUSTS UP TO 35 KTS WILL
ALSO BE POSSIBLE OVER THE HIGHER ELEVATIONS OF THE SIERRA AND
THROUGH FAVORED CANYONS AND PASSES DURING THE OVERNIGHT AND EARLY
MORNING HOURS.
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS66 KSTO 172321
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
330 PM PST SAT JAN 17 2009
.DISCUSSION...
STILL SOME LIGHT FOG IN THE NORTHERN SAN JOAQUIN AND SOUTHERN SAC
VALLEY THIS AFTERNOON...OTHERWISE SKIES ARE CLEAR UNDER STRONG UPPER
LEVEL RIDGE. NORTHEASTERLY SURFACE GRADIENTS HAVE WEAKENED SLIGHTLY
AND AS A RESULT...WINDS ARE FAIRLY LIGHT MOST AREAS. AIRMASS RUNNING
JUST A LITTLE COOLER TODAY AND TEMPERATURES RUNNING A LITTLE COOLER
MOST AREAS. TEMPERATURES ARE MUCH COOLER...NEARLY TEN DEGREES...IN
THE NORTHERN SACRAMENTO VALLEY DUE TO THE LACK OF LIGHT NORTHERLY
WINDS WHICH BROUGHT ADIABATIC WARMING ON FRIDAY. AS SURFACE HIGH
OVER THE PACIFIC NORTHWEST DIGS SOUTHWARD INTO GREAT
BASIN...NORTHEAST TO EAST SURFACE GRADIENT INCREASES A BIT TONIGHT
SO SHOULD SEE BREEZY NORTHEAST WINDS AGAIN OVERNIGHT ESPECIALLY OVER
THE SIERRA FOOTHILLS. THIS SHOULD LIMIT NIGHTTIME FOG TONIGHT TO THE
SOUTHERN SAC VALLEY AND NORTHERN SAN JOAQUIN VLY. UPPER RIDGE
FORECAST TO SHIFT FROM JUST OFFSHORE TO JUST EAST OF THE FORECAST
AREA BY SUNDAY AFTERNOON SO SHOULD SEE A LITTLE MORE COOLING FOR
SECOND HALF OF WEEKEND. ONLY MINOR CHANGES EXPECTED ON MONDAY AS
UPPER PRESSURE PATTERN ONLY SHIFTING SLIGHTLY. CONTINUED SLOW
COOLING TREND CONTINUES AS UPPER RIDGE SHIFTS EAST ON TUESDAY AND
PACIFIC TROUGH APPROACHES THE NORTH COAST.
.EXTENDED DISCUSSION (TUESDAY NIGHT THROUGH SATURDAY)...EXTENDED
MODELS CONTINUE TO STRUGGLE WITH THE TUESDAY NIGHT THROUGH SATURDAY
PERIOD. ALTHOUGH THE 12Z GFS AND CANADIAN ARE BOTH SIMILAR IN
TIMING WITH THE EXTENDED SYSTEMS...THEY SEEMS TO BE BREAKING DOWN
THE CURRENT RIDGE TOO QUICKLY BY BRINGING A SYSTEM INTO THE PACIFIC
NORTHWEST TUESDAY NIGHT AND WEDNESDAY...FOLLOWED BY ANOTHER SYSTEM
ON FRIDAY. MEANWHILE...THE ECMWF AND UKMET ARE SIMILAR AND MORE
CONSISTENT FROM RUN TO RUN...KEEPING A LONGER WAVE TROUGH OFF THE
COAST THROUGH AT LEAST WEDNESDAY...SPLITTING ITS ENERGY AND MOISTURE
AS IT MOVES INLAND SOME TIME WEDNESDAY AND WEDNESDAY NIGHT.
UNFORTUNATELY...IT APPEARS THAT THE BRUNT OF THE MOISTURE WILL THEN
MOVES INTO SOUTHERN CALIFORNIA...LIMITING ANY REAL CHANCE AT SOME
PRECIPITATION OVER NORTHERN CALIFORNIA. A SECONDARY SYSTEM WOULD
THEN MOVE INTO CENTRAL OR SOUTHERN CALIFORNIA SOMETIME FRIDAY NIGHT
AND SATURDAY...ONLY GIVING THE NORTHERN HALF OF THE STATE A GLANCING
CHANCE OF SOME SHOWERS. CONFIDENCE IS LOW IN THESE SOLUTIONS...BUT
TEND TO BELIEVE THE LATTER MODELS SEEM MORE REASONABLE. EITHER WAY
THOUGH... DOUBTFUL THAT NORTHERN CALIFORNIA WILL SEE MUCH OF
ANYTHING...WITH PRIMARILY DRY CONDITIONS AND MORE SEASONAL
TEMPERATURES PREVAILING. DUE TO THE UNCERTAINTY THOUGH....HAVE KEPT
A SLIGHT CHANCE IN THE FORECAST...MAINLY OVER THE HIGHER TERRAIN
THROUGH THE PERIOD. PALMER
&&
.AVIATION...HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH THE
NEXT 24 HOURS...WITH PRIMARILY VFR CONDITIONS PREVAILING. AREAS OF
MVFR VISIBILITIES IN HAZY OR MIST WILL CONTINUE SOUTH OF KMYV
THROUGH THIS EVENING...WITH LOCAL IFR/LIFR CONDITIONS POSSIBLY
DEVELOPING IN FOG OR MIST OVERNIGHT. LOCAL NORTHEAST TO EAST
WINDS GUSTS UP TO 35 KTS WILL ALSO BE POSSIBLE OVER THE HIGHER
ELEVATIONS OF THE SIERRA AND THROUGH FAVORED CANYONS AND PASSES
DURING THE OVERNIGHT AND EARLY MORNING HOURS.
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS66 KSTO 171744
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
930 AM PST SAT JAN 17 2009
.DISCUSSION...
SOME PATCHY FOG IN THE CENTRAL VALLEY THIS MORNING...OTHERWISE SKIES
ARE CLEAR UNDER STRONG UPPER LEVEL RIDGE. SURFACE HIGH OVER PACIFIC
NORTHWEST GENERATING SOME LIGHT NORTH WINDS OVER THE NORTHERN CWA
AND THIS BREEZE HAS KEPT FOG GENERALLY OUT OF THE NORTHERN
SACRAMENTO VALLEY. WINDS JUST A BIT LIGHTER THIS MORNING AND AS A
RESULT TEMPERATURES RUNNING A BIT COOLER SOME LOCATIONS ESPECIALLY
IN THE NORTHERN SAC VALLEY WHERE THE RED BLUFF TEMPERATURE IS
RUNNING 10 DEGREES BELOW 24 HOURS AGO. ELSEWHERE...TEMPERATURES ARE
RUNNING SIMILAR TO YESTERDAY. WEAK UPPER LOW OVER SOCAL HAS SHIFTED
SLIGHTLY NORTHWARD TODAY. THIS SHOULD BRING A SLIGHT COOLING OF THE
AIRMASS SO CURRENT FORECAST PACKAGE WHICH HAS SLIGHTLY COOLER
TEMPERATURES LOOKS OKAY FOR NOW KEEPING MAX TEMPS TODAY A LITTLE
BELOW DAILY RECORDS. AS SURFACE HIGH DIGS SOUTHWARD INTO GREAT
BASIN...NORTHEAST TO EAST SURFACE GRADIENT INCREASES A BIT SO SHOULD
SEE BREEZY NORTHEAST WINDS AGAIN TONIGHT ESPECIALLY OVER THE SIERRA
FOOTHILLS. THIS SHOULD LIMIT NIGHTTIME FOG TONIGHT TO THE SOUTHERN
SAC VALLEY AND NORTHERN SAN JOAQUIN VLY AND COVERED WELL IN CURRENT
FORECAST PACKAGE. UPPER RIDGE FORECAST TO SHIFT FROM JUST OFFSHORE
TO JUST EAST OF THE FORECAST AREA BY SUNDAY AFTERNOON SO SHOULD SEE
A LITTLE MORE COOLING FOR SECOND HALF OF WEEKEND. ONLY MINOR CHANGES
EXPECTED ON MONDAY AS UPPER PRESSURE PATTERN ONLY SHIFTING SLIGHTLY.
CONTINUED SLOW COOLING TREND CONTINUES AS UPPER RIDGE SHIFTS EAST ON
TUESDAY AND WEAK PACIFIC TROUGH APPROACHES THE NORTH COAST. LATEST
GFS AND CANADIAN MODELS RIDE THIS TROUGH OVER RIDGE AND KEEP PRECIP
NORTH OF FORECAST AREA WHILE LAST EVENINGS RUN OF THE ECMWF DIGS A
PORTION OF THE TROUGH UNDER THE RIDGE BRINGING MUCH OF THE STATE A
THREAT OF LIGHT PRECIP. CONSIDERING UNUSUAL STRENGTH OF THE
RIDGE...INCLINED TO GO WITH DRIER SOLUTIONS. STRONGER SYSTEM
FORECAST BY GFS AND CANADIAN MODELS TO BEGIN CARVING A PATH TO THE
PACIFIC WESTERLIES BACK SOUTHWARD TO THE WEST COAST BUT MUCH
UNCERTAINTY EXISTS IN THIS 7 DAY TIMEFRAME.
&&
.AVIATION...HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH THE
NEXT 24 HOURS...WITH PRIMARILY VFR CONDITIONS PREVAILING.
HOWEVER...AREAS MVFR VISIBILITIES WILL BE POSSIBLE TODAY IN HAZY OR
MIST SOUTH OF KMYV...WITH LOCAL IFR/LIFR CONDITIONS POSSIBLE WITH
FOG OR MIST THROUGH 19Z. LOCAL NORTHEAST TO EAST WINDS GUSTS UP TO
40 KTS WILL ALSO BE POSSIBLE OVER THE HIGHER ELEVATIONS OF THE
SIERRA AND THROUGH FAVORED CANYONS AND PASSES.
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
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