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Updated:
9/9/10 12:05pm
Foresthill Weather.com
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Todays Low: 47.1 °F 7:12am Current Conditions Wind
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Temperture
60.1 °F
Temp Rate:
2.58 °F
2.58 °F
Heat Index:
61.9 °F
61.9 °F
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60.1 °F
60.1 °F
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Todays High: 60.2 °F 11:55am
Todays Low: 47.1 °F 7:12am Current Conditions Wind
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5
Gusting to
6
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Barometer:
Baro Trend:
4 mph
19 mph
60%
0.05 in
46.2 °F
29.98 in
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0.00
0.00
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0.00
Foresthill Fire Safe Council Yuba Net.com Outlook
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NATIONAL WEATHER SERVICE FORECAST DISCUSSION
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AREA FORECAST DISCUSSION
FXUS66 KSTO 091609 AFDSTO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 910 AM PDT THU SEP 9 2010 .DISCUSSION...WATER VAPOR IMAGERY CONTINUES TO SHOW AN UPPER LEVEL TROUGH OF LOW PRESSURE OVER THE WESTERN US...WITH THE MAIN AREA OF LOW PRESSURE NOW OVER NORTHERN NEVADA AND MORE NORTHERLY FLOW FILTERING INTO NORTHERN CALIFORNIA. AS A RESULT...SKIES ARE STARTING TO CLEAR ACROSS THE REGION. THE FEW EXCEPTIONS ARE IN THE NORTHERN MOUNTAINS SOUTH TO ABOUT INTERSTATE 80...WHERE A WEAK WAVE MOVING AROUND THE BACK SIDE OF THE TROUGH IS GENERATING CLOUDS OVER THE MOUNTAINS. THE OTHER IS ALONG THE WEST SIDE OF THE SACRAMENTO VALLEY DOWN TO THE DELTA...WHERE SOME LOW CLOUDS HAVE DEVELOPED FROM RESIDUAL MOISTURE. EXPECT THIS TREND OF DRIER AND CLEARER TO CONTINUE THROUGH THE DAY. THEREFORE...HAVE UPDATED THE FORECAST THIS MORNING TO ADJUST SKY CONDITIONS AND TREND TO CLEARER SKIES THIS AFTERNOON. AS FOR TEMPERATURES...EXPECT ANOTHER UNSEASONABLY COOL AND MORE FALL-LIKE DAY ACROSS THE REGION...WITH VALLEY AND FOOTHILL TEMPERATURES PREDOMINATELY IN THE 70S. LOOKING AT A RECAP OF YESTERDAY/S PRECIPITATION...IT APPEARS THAT MOST VALLEY LOCATIONS ONLY SAW A FEW HUNDREDTHS. HOWEVER...IN AREAS WERE THUNDERSTORMS OCCURRED...HAVE FOUND A FEW LOCATIONS REPORTING UP TO A HALF INCH...WITH STONYFORD REPORTING THE MOST AT 0.88 INCHES. IN THE FOOTHILLS AND SURROUNDING MOUNTAINS...TOTALS WERE HIGHER...RANGING PRIMARILY BETWEEN A QUARTER AND THREE QUARTERS INCH. HOWEVER...WHITMORE...SHINGLETOWN...AND MANZANITA LAKE ALL REPORTED OVER AN INCH...WITH WHITMORE REPORTING THE MOST AT 1.57 INCHES. PALMER && .AVIATION...DRIER NORTHERLY TO NORTHWESTERLY FLOW IS STARTING TO FILTER OVER THE REGION. HOWEVER...LOW CLOUDS HAVE DEVELOP THIS MORNING ACROSS THE SOUTHERN SACRAMENTO VALLEY AND DELTA...WITH AREAS OF IFR/MVFR CEILINGS POSSIBLE THROUGH 18Z. SOME LOW CLOUDS WILL LINGER OVER THE NORTHERN MOUNTAINS SOUTHWARD TO ABOUT INTERSTATE 80...WITH AREAS OF MVFR/IFR CONDITIONS POSSIBLE THROUGH 00Z. OTHERWISE...EXPECT IMPROVING CONDITIONS THROUGH THE DAY...WITH VFR CONDITIONS PREVAILING. && .STO WATCHES/WARNINGS/ADVISORIES...NONE. && $$
FXUS66 KSTO 091045 AFDSTO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 345 AM PDT THU SEP 9 2010 .DISCUSSION... UPPER TROUGH LIFTING OUT ACROSS THE GREAT BASIN EARLY THIS MORNING. NORTHERLY FLOW ALOFT AND SUBSIDENCE BEGINNING TO TAKE HOLD IN ITS WAKE WITH SHOWERS HAVING ENDED. IR IMAGERY SHOWS SOME LOW CLOUDS LINGERING...BUT HAS SHOWN A DEFINITE DECREASING TREND IN CLOUD COVERAGE THE PAST FEW HOURS. BROAD ZONAL PATTERN EXPECTED TO DEVELOP BY FRIDAY AND CONTINUE FOR MUCH OF THE NEXT WEEK AS THE WESTERLIES RETREAT INTO THE PACNW AND FLAT RIDGING COVERS THE REGION. THIS WILL RESULT IN A WARMUP OF TEMPERATURES DURING THE NEXT COUPLE OF DAYS. THE TAIL END OF WEAK SYSTEMS PASSING TO THE NORTH MAY BRING SOME HIGH CLOUDS AT TIMES... BUT OTHERWISE LOOKS LIKE DRY AND SEASONABLY MILD WEATHER WILL PERSIST FOR THE FORESEEABLE FUTURE. && .AVIATION... UPR TROF CONTS TO MOV E OF THE FCST AREA TDA AS EPAC UPR RDGG BGNS TO BLD INLD OVR NORCAL. GENLY VFR CONDS OVR INTR NORCAL NXT 24 HRS EXC LCL MVFR/IFR CONDS VCNTY DELTA TIL 18Z AND OMTNS TIL 00Z FRI. N-NW FLOW ALF. && .STO WATCHES/WARNINGS/ADVISORIES...NONE. && $$
FXUS66 KSTO 090258 CCA AFDSTO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 800 PM PDT WED SEP 8 2010 .DISCUSSION... SOME SCATTERED THUNDERSTORMS DEVELOPED THIS AFTERNOON THROUGH EARLY EVENING WITH SOME HEAVY DOWNPOURS FOR SOME LOCAL AREAS BETWEEN ONE HALF TO JUST OVER AN INCH OF RAIN. EARLIER LIGHTNING FROM THUNDERSTORMS KNOCKED OUT SOME POWER FOR PEOPLE NEAR ANDERSON AND REDDING. THE THUNDERSTORM ACTIVITY IS SLOWLY DIEING DOWN BUT SOME LOCAL HEAVY DOWNPOURS MAY CONTINUE THROUGH AROUND 10 PM OVER THE EASTERN CENTRAL VALLEY AND ADJACENT FOOTHILLS. SOME SHOWERS WILL LIKELY CONTINUE OVERNIGHT MAINLY FOR THE WESTERN SLOPES AND FOOTHILLS WITH A SLIGHT CHANCE OF SOME SHOWERS OVER THE EASTERN SACRAMENTO VALLEY. THIS SYSTEM LOOKS COLD ENOUGH FOR SOME SNOW TO FALL OVER THE HIGHER ELEVATIONS BUT ANY ACCUMULATIONS SHOULD BE MINIMAL AT AN INCH OR LESS. SHOWERS SHOULD CONTINUE OVER THE WESTERN SLOPES ON THURSDAY WITH A CHANCE OF ISOLATED THUNDERSTORMS IN THE AFTERNOON...BUT THE THUNDERSTORMS SHOULD BE EAST OF THE CREST. TEMPERATURES SHOULD ALSO WARM ABOUT 5 DEGREES FOR MOST LOCATIONS ON THURSDAY BUT STILL MAINLY STAYING COOL AND IN THE 70S. BY FRIDAY LIGHT NORTHERLY FLOW AND A WARMER AIRMASS SHOULD WILL HELP TO WARM TEMPERATURES INTO THE MID 80S TO AROUND 90 DEGREES IN THE CENTRAL VALLEY. .AVIATION... UPPER LEVEL TROUGH MOVING THROUGH THE AREA TONIGHT BRINGING SCT SHOWERS AND ISOLATED THUNDERSTORMS OVER SACRAMENTO VALLEY AND MOUNTAINS TROUGH 06Z THEN WDLY SCT SHRA AFTERWORDS. GENERALLY VFR CONDITIONS IN THE VALLEY EXCEPT LOCAL MVFR CONDITIONS ARE POSSIBLE WITH HEAVIER SHRA. MVFR CONDITIONS WITH AREAS OF MVFR/IFR CONDITIONS IN THE MOUNTAINS TONIGHT. THE TROUGH SHIFTS TO THE EAST ON THURSDAY WITH IMPROVING CONDITIONS. && .STO WATCHES/WARNINGS/ADVISORIES...NONE. && $$
FXUS66 KSTO 082243 CCA AFDSTO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 335 PM PDT WED SEP 8 2010 .DISCUSSION... IT CERTAINLY FEELS MORE LIKE FALL THAN LATE SUMMER AS A FALL-LIKE TROUGH TRAVERSES THROUGH INTERIOR NORTHERN CALIFORNIA. A COLD FRONT MOVED THROUGH THE AREA EARLIER THIS MORNING AND BROUGHT A FEW LIGHT SHOWERS PRIMARILY TO THE WEST SLOPES OF THE NORTHERN SIERRA. NOW IN THE POST-FRONTAL REGIME...OUR WEATHER IS PRIMARILY BEING DICTATED BY AN AREA OF COOL TEMPS ALOFT. CUMULUS CLOUDS DOMINATE THE SKIES AND SHOWERS HAVE BEEN ACTIVELY FORMING GENERALLY WELL NORTH OF INTERSTATE 80. ATMOSPHERIC CONDITIONS HAVE BEEN UNSTABLE ENOUGH SUCH THAT THUNDERSTORMS FORMING ALONG THE COASTAL RANGE HAVE DRIFTED EASTWARD INTO THE VALLEY AND MAINTAINED INTENSITY OR EVEN IN SOME CASES HAVE ENHANCED A BIT. IT IS NOTABLE THAT MANY OF THESE SHOWERS WILL IMPACT INTERSTATE 5 THIS AFTERNOON/EVENING. THESE THUNDERSTORMS HAVE BEEN FAIRLY EFFICIENT LIGHTNING AND RAIN PRODUCERS...NEARLY 100 LIGHTNING STRIKES HAVE BEEN DETECTED AS OF THIS WRITING. SMALL HAIL AND LOCALLY GUSTY WINDS ARE POSSIBILITIES AS WELL WITH THESE CELLS. IT SHOULD BE STRESSED THAT FOR MANY INTERIOR NORTHERN CALIFORNIA LOCALITIES...THIS HAS BEEN THE FIRST RAINFALL IN SEVERAL MONTHS. RAIN MIXED WITH ACCUMULATED OIL ON ROADWAYS CAN MAKE FOR DANGEROUSLY SLICK CONDITIONS. TRAVELERS SHOULD DRIVE WITH EXTRA CAUTION IN AREAS THAT HAVE SEEN OR ARE LIKELY TO SEE RAIN SHOWERS. THE COMBINATION OF SUBSTANTIAL SYNOPTIC COOLING WITH EXTENSIVE CLOUD COVER AND SCATTERED SHOWERS HAS LED TO QUITE A BIT OF COOLING. AFTERNOON TEMPERATURES ARE RUNNING ANYWHERE FROM 8 TO 21 DEGREES COOLER THAN YESTERDAY...WITH THE GREATEST DEGREE OF COOLING OCCURRING TOWARDS THE NORTHERN SAC VALLEY. SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO THE EVENING BEFORE DECREASING IN INTENSITY AS THE UPPER TROUGH SHIFTS EASTWARD. MAY CONTINUE TO SEE WRAPAROUND SHOWERS OVER THE MOUNTAINS INTO THURSDAY. THURSDAY WILL BRING A SLIGHT WARMING TO MOST OF THE AREA...THOUGH COLD AIR ADVECTION WILL KEEP THINGS ON THE COOL SIDE OF THE SPECTRUM. EXPECT HIGHS TO ONLY REACH THE MID TO UPPER 70S THROUGH THE VALLEY...WITH 50S AND 60S OVER THE MOUNTAINS. THESE VALUES EQUATE TO HIGHS 10 TO 15 DEGREES BELOW NORMAL. A SLOW AND GRADUAL WARMUP IS EXPECTED BEGINNING FRIDAY AND INTO THE WEEKEND AS FLOW ALOFT BECOMES LESS CYCLONIC AND MORE ZONAL. UNDER MOSTLY SUNNY SKIES...FRIDAY AND SATURDAY TEMPS SHOULD REACH THE 80S THROUGH THE VALLEY WITH 60S AND 70S OVER THE HIGHER ELEVATIONS. A MODEST DELTA BREEZE WILL BE BLOWING...BUT SHOULDNT CONTRIBUTE TO A SUBSTANTIAL COOLING EFFECT. DANG .EXTENDED DISCUSSION (SUNDAY THROUGH WEDNESDAY)... NORTHERN CALIFORNIA IS BETWEEN AN UPPER LEVEL TROUGH OVER THE EASTERN PACIFIC AND WESTERN CANADA AND AN UPPER LEVEL RIDGE OVER THE GREAT BASIN ON SUNDAY AND MONDAY. THIS WILL BRING NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES AND DRY WEATHER. THE TROUGH DEEPENS OVER THE EASTERN PACIFIC MID WEEK BRINGING BELOW NORMAL TEMPERATURES TUESDAY AND WEDNESDAY. THE TROUGH MAY MOVE ONSHORE FRIDAY INTO SATURDAY BRINGING COOLER TEMPERATURES AND A THREAT OF PRECIPITATION FOR NEXT FRIDAY AND SATURDAY. THE MODELS ARE GETTING INTO BETTER AGREEMENT WITH THIS SYSTEM WITH THE 12Z GFS...ECMWF...AND GEM INDICATING POSSIBLE PRECIPITATION...ESPECIALLY OVER THE NORTHERN PORTION OF THE AREA. .AVIATION... UPPER LEVEL TROUGH MOVING THROUGH THE AREA TONIGHT BRINGING SCT SHOWERS AND THUNDERSTORMS OVER THE MOUNTAINS AND IN THE THE VALLEY...MAINLY NORTH OF INTERSTATE 80. GENERALLY VFR CONDITIONS EXCEPTED IN THE VALLEY EXCEPT LOCAL MVFR CONDITIONS ARE POSSIBLE WITH SHRA AND TSRA. MVFR CONDITIONS WITH AREAS OF IFR/LIFR CONDITIONS IN THE MOUNTAINS TONIGHT. THE TROUGH SHIFTS TO THE EAST ON THURSDAY WITH IMPROVING CONDITIONS. GUSTY SOUTHWESTERLY WINDS TO 30KTS IN THE VALLEY AND DELTA THIS EVENING AND GUSTS UP TO 35KTS IN THE MOUNTAINS TONIGHT. && .STO WATCHES/WARNINGS/ADVISORIES...NONE. && $$
FXUS66 KSTO 082234 AFDSTO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 335 PM PDT WED SEP 8 2010 .DISCUSSION... IT CERTAINLY FEELS MORE LIKE FALL THAN LATE SUMMER AS A FALL-LIKE TROUGH TRAVERSES THROUGH INTERIOR NORTHERN CALIFORNIA. A COLD FRONT MOVED THROUGH THE AREA EARLIER THIS MORNING AND BROUGHT A FEW LIGHT SHOWERS PRIMARILY TO THE WEST SLOPES OF THE NORTHERN SIERRA. NOW IN THE POST-FRONTAL REGIME...OUR WEATHER IS PRIMARILY BEING DICTATED BY AN AREA OF COOL TEMPS ALOFT. CUMULUS CLOUDS DOMINATE THE SKIES AND SHOWERS HAVE BEEN ACTIVELY FORMING GENERALLY WELL NORTH OF INTERSTATE 80. ATMOSPHERIC CONDITIONS HAVE BEEN UNSTABLE ENOUGH SUCH THAT THUNDERSTORMS FORMING ALONG THE COASTAL RANGE HAVE DRIFTED EASTWARD INTO THE VALLEY AND MAINTAINED INTENSITY OR EVEN IN SOME CASES HAVE ENHANCED A BIT. IT IS NOTABLE THAT MANY OF THESE SHOWERS WILL IMPACT INTERSTATE 5 THIS AFTERNOON/EVENING. THESE THUNDERSTORMS HAVE BEEN FAIRLY EFFICIENT LIGHTNING AND RAIN PRODUCERS...NEARLY 100 LIGHTNING STRIKES HAVE BEEN DETECTED AS OF THIS WRITING. SMALL HAIL AND LOCALLY GUSTY WINDS ARE POSSIBILITIES AS WELL WITH THESE CELLS. IT SHOULD BE STRESSED THAT FOR MANY INTERIOR NORTHERN LOCALITIES... THIS HAS BEEN THE FIRST RAINFALL IN SEVERAL MONTHS. RAIN MIXED WITH ACCUMULATED OIL ON ROADWAYS CAN MAKE FOR DANGEROUSLY SLICK CONDITIONS. TRAVELERS SHOULD DRIVE WITH EXTRA CAUTION IN AREAS THAT HAVE SEEN OR ARE LIKELY TO SEE RAIN SHOWERS. THE COMBINATION OF SUBSTANTIAL SYNOPTIC COOLING WITH EXTENSIVE CLOUD COVER AND SCATTERED SHOWERS HAS LED TO QUITE A BIT OF COOLING. AFTERNOON TEMPERATURES ARE RUNNING ANYWHERE FROM 8 TO 21 DEGREES COOLER THAN YESTERDAY...WITH THE GREATEST DEGREE OF COOLING OCCURRING TOWARDS THE NORTHERN SAC VALLEY. SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO THE EVENING BEFORE DECREASING IN INTENSITY AS THE UPPER TROUGH SHIFTS EASTWARD. MAY CONTINUE TO SEE WRAPAROUND SHOWERS OVER THE MOUNTAINS INTO THURSDAY. THURSDAY WILL BRING A SLIGHT WARMING TO MOST OF THE AREA...THOUGH COLD AIR ADVECTION WILL KEEP THINGS ON THE COOL SIDE OF THE SPECTRUM. EXPECT HIGHS TO ONLY REACH THE MID TO UPPER 70S THROUGH THE VALLEY...WITH 50S AND 60S OVER THE MOUNTAINS. THESE VALUES EQUATE TO HIGHS 10 TO 15 DEGREES BELOW NORMAL. A SLOW AND GRADUAL WARMUP IS EXPECTED BEGINNING FRIDAY AND INTO THE WEEKEND AS FLOW ALOFT BECOMES LESS CYCLONIC AND MORE ZONAL. UNDER MOSTLY SUNNY SKIES...FRIDAY AND SATURDAY TEMPS SHOULD REACH THE 80S THROUGH THE VALLEY WITH 60S AND 70S OVER THE HIGHER ELEVATIONS. A MODEST DELTA BREEZE WILL BE BLOWING...BUT SHOULDNT CONTRIBUTE TO A SUBSTANTIAL COOLING EFFECT. DANG .EXTENDED DISCUSSION (SUNDAY THROUGH WEDNESDAY)... NORTHERN CALIFORNIA IS BETWEEN AN UPPER LEVEL TROUGH OVER THE EASTERN PACIFIC AND WESTERN CANADA AND AN UPPER LEVEL RIDGE OVER THE GREAT BASIN ON SUNDAY AND MONDAY. THIS WILL BRING NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES AND DRY WEATHER. THE TROUGH DEEPENS OVER THE EASTERN PACIFIC MID WEEK BRINGING BELOW NORMAL TEMPERATURES TUESDAY AND WEDNESDAY. THE TROUGH MAY MOVE ONSHORE FRIDAY INTO SATURDAY BRINGING COOLER TEMPERATURES AND A THREAT OF PRECIPITATION FOR NEXT FRIDAY AND SATURDAY. THE MODELS ARE GETTING INTO BETTER AGREEMENT WITH THIS SYSTEM WITH THE 12Z GFS...ECMWF...AND GEM INDICATING POSSIBLE PRECIPITATION...ESPECIALLY OVER THE NORTHERN PORTION OF THE AREA. .AVIATION... UPPER LEVEL TROUGH MOVING THROUGH THE AREA TONIGHT BRINGING SCT SHOWERS AND THUNDERSTORMS OVER THE MOUNTAINS AND IN THE THE VALLEY...MAINLY NORTH OF INTERSTATE 80. GENERALLY VFR CONDITIONS EXCEPTED IN THE VALLEY EXCEPT LOCAL MVFR CONDITIONS ARE POSSIBLE WITH SHRA AND TSRA. MVFR CONDITIONS WITH AREAS OF IFR/LIFR CONDITIONS IN THE MOUNTAINS TONIGHT. THE TROUGH SHIFTS TO THE EAST ON THURSDAY WITH IMPROVING CONDITIONS. GUSTY SOUTHWESTERLY WINDS TO 30KTS IN THE VALLEY AND DELTA THIS EVENING AND GUSTS UP TO 35KTS IN THE MOUNTAINS TONIGHT. && .STO WATCHES/WARNINGS/ADVISORIES...NONE. && $$
FXUS66 KSTO 081558 AFDSTO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 900 AM PDT WED SEP 8 2010 .DISCUSSION... IT CERTAINLY FEELS MORE LIKE FALL THAN LATE SUMMER AS A FALL-LIKE TROUGH DROPS SOUTH INTO NORTHERN CALIFORNIA. A CLEARLY DEFINED SW/NE ORIENTED COLD FRONT HAS SWEPT THROUGH THE NORTHERN PORTIONS OF THE STATE AND IS ALIGNED NEAR THE THE I-80 CORRIDOR AS OF THIS WRITING. A STRONG ONSHORE FLOW KICKED UP AHEAD OF THE FRONTAL SYSTEM...AND ALSO AIDED IN DEEPENING THE MARINE LAYER. INTERESTINGLY...BOTH THE FORT ORD PROFILER AND THE 12Z KOAK SHOW THE MARINE-INFLUENCED LAYER HAVING DEEPENED TO AROUND 6500 FT THIS MORNING! WITH THOSE PARAMETERS IN PLACE IT SHOULD COME AS NO SURPRISE THAT MARINE STRATUS SHOT THROUGH THE CARQUINEZ STRAIT AND STARTED FORMING ALONG THE EASTERN PORTIONS OF THE SOUTHERN SACRAMENTO VALLEY. BEHIND THE FRONT...EXPANSIVE CUMULIFORM CLOUDINESS HAS ALREADY STARTED FORMING UNDER THE COOL POOL ALOFT. SHOWERS HAVE BEEN FORMING IN THE NORTHERN SACRAMENTO VALLEY AND SURROUNDING MOUNTAINS...WITH BRIEF HEAVY RAINFALL HAVING BEEN REPORTED. DUE TO THE EXPANSIVE NATURE OF THE CLOUD DECK AND THE SYNOPTIC COOLING ALREADY TAKING PLACE...TEMPERATURES WILL BE VERY SLOW TO CREEP UP TODAY. IN FACT...WOULDN`T BE SURPRISED TO SEE A FEW VALLEY LOCATIONS STAY SOUTH OF 70 DEGREE HIGHS THIS AFTERNOON. MANY INTERIOR NORTHERN CALIFORNIA LOCATIONS HAVE NOT SEEN TEMPS THIS COOL SINCE MAY. ALSO GIVEN THE PRECIPITATION EXTENT EARLY THIS MORNING...WILL UPDATE THE FORECAST TO BETTER REPRESENT CURRENT AND FUTURE CONDITIONS. DANG .PREVIOUS DISCUSSION... ANOTHER SHORTWAVE TROUGH PIVOTING AROUND THE BACKSIDE OF THE LOW AND NOW OFF THE NORCAL COAST WILL DIG INTO NORCAL THIS AFTERNOON BRINGING INCREASED INSTABILITY AND AN INCREASED CHANCE OF SHOWERS TO MUCH OF THE AREA. PRECIPITATION AMOUNTS ARE STILL EXPECTED TO BE FAIRLY LIGHT AND GENERALLY UNDER 1/4 INCH. INSTABILITY PROGS SHOW THE BEST THREAT OF AFTERNOON THUNDERSTORMS WILL BE OVER THE HIGHER TERRAIN WITH LITTLE THREAT OF THUNDERSTORMS IN THE VALLEY. MAIN UPPER TROUGH FORECAST TO SWING EAST OF THE FORECAST AREA TONIGHT AND THURSDAY MORNING. SHORTWAVES DIGGING DOWN BACK SIDE OF THIS LOW COULD BRING THREAT OF PRECIP TO THE SIERRA CASCADE RANGE BUT NORTHERLY FLOW ALOFT SHOULD END THREAT ELSEWHERE. SHOULD SEE CLEARING SKIES BY THURSDAY AFTERNOON WITH WARMER TEMPERATURES ALTHOUGH STILL WELL BELOW NORMAL FOR THIS TIME OF YEAR. STILL MORE WARMING EXPECTED ON FRIDAY AS FAIRLY FLAT UPPER RIDGE SLIDES OVER REGION BUT HIGH TEMPS STILL FORECAST TO REMAIN A LITTLE BELOW NORMAL. A SERIES OF WEATHER SYSTEMS PASSING WELL TO THE NORTH OF THE AREA WILL KEEP RIDGING OVER THE SOUTHWEST U.S. SUPPRESSED. THIS WILL HELP KEEP DAYTIME HIGHS FROM SATURDAY THROUGH THE MIDDLE OF NEXT WEEK FROM CLIMBING SIGNIFICANTLY SO EXPECTING TEMPERATURES THROUGH EXTENDED PERIOD TO REMAIN BELOW NORMAL. EXTENDED MODELS HINTING AT TROUGHING ALONG THE WEST COAST TOWARDS THE END OF NEXT WEEK AND EVEN SUGGESTING PRECIP THREAT BUT THIS WOULD BE BEYOND CURRENT FORECAST PERIOD AND RUN TO RUN CONSISTENCY IN THIS TIME FRAME HAS BEEN NOT BEEN GOOD WITH STRENGTH OF THIS SYSTEM. .AVIATION... UPPER TROUGH MOVING THROUGH INTERIOR NORTHERN CALIFORNIA TODAY AND BRINGING A WIDE VARIETY OF WEATHER. AREAS OF MVFR/IFR CIGS POSSIBLE THROUGH THE SOUTHERN SACRAMENTO VALLEY THROUGH 18-19Z. BEHIND THE FRONT...SCATTERED TO NUMEROUS RAIN SHOWERS ARE DEVELOPING AND MAY BRING PERIODS OF MVFR TO LOCAL IFR CIGS/VSBYS THROUGH ABOUT 06Z...GENERALLY NORTH OF THE I-80 CORRIDOR. LOCAL SOUTH TO SOUTHWESTERLY WIND GUSTS TO 25 KTS POSSIBLE THROUGH THE DELTA AND PORTIONS OF THE CENTRAL VALLEY...AND TO 30-35 KTS OVER HIGHER MOUNTAIN TERRAIN THROUGH ABOUT 04Z THURSDAY. && .STO WATCHES/WARNINGS/ADVISORIES...NONE. && $$
FXUS66 KSTO 081203 AFDSTO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 330 AM PDT WED SEP 8 2010 .DISCUSSION... COLD FOR THE SEASON UPPER LOW NOW CENTERED NEAR THE OREGON/WASHINGTON STATE BORDER WITH A SHORTWAVE TROUGH ROTATING AROUND SOUTHERN PORTION OF LOW AND THROUGH NORCAL AT THIS TIME. RADAR HAS BEEN PICKING UP LIGHT ECHOS ACROSS THE NORTHERN HALF OF THE CWA MOST OF THE EVENING BUT SO FAR NO REPORTS OF ANY PRECIP HITTING THE GROUND. UPPER LOW WILL BRING SIGNIFICANT AIRMASS COOLING TODAY AS IT DROPS SOUTHWARD. OVER THE SOUTHERN CWA MOUNTAINS WHERE CLOUDINESS FROM THE SHORTWAVE HAS NOT REACHED...TEMPERATURES ARE RUNNING FROM 10 TO 15 DEGREES BELOW 24 HOURS AGO. OVER THE NORTHERN CWA CLOUD COVER IS KEEPING TEMPERATURES WARMER THIS MORNING. FORT ORD PROFILER INDICATING A SIGNIFICANT INCREASE IN MARINE LAYER OVER THE LAST SEVERAL HOURS AS IT RESPONDS TO THE APPROACHING LOW AND PATCHY STRATUS APPEARS TO HAVE MADE IT INTO THE SOUTHERN SACRAMENTO VALLEY. COMBINATION OF CLOUDS AND COOLER AIRMASS WILL LIKELY KEEP TEMPERATURES IN THE CENTRAL VALLEY IN THE 70S TODAY. AT THIS TIME NO RECORD LOW MAXES ARE PREDICTED BUT TEMPERATURES IN MANY SACRAMENTO VALLEY LOCATIONS HAVE NOT SEEN HIGH TEMPERATURES THIS LOW SINCE MAY. ANOTHER SHORTWAVE TROUGH PIVOTING AROUND THE BACKSIDE OF THE LOW AND NOW OFF THE NORCAL COAST WILL DIG INTO NORCAL THIS AFTERNOON BRINGING INCREASED INSTABILITY AND AN INCREASED CHANCE OF SHOWERS TO MUCH OF THE AREA. PRECIPITATION AMOUNTS ARE STILL EXPECTED TO BE FAIRLY LIGHT AND GENERALLY UNDER 1/4 INCH. INSTABILITY PROGS SHOW THE BEST THREAT OF AFTERNOON THUNDERSTORMS WILL BE OVER THE HIGHER TERRAIN WITH LITTLE THREAT OF THUNDERSTORMS IN THE VALLEY. MAIN UPPER TROUGH FORECAST TO SWING EAST OF THE FORECAST AREA TONIGHT AND THURSDAY MORNING. SHORTWAVES DIGGING DOWN BACK SIDE OF THIS LOW COULD BRING THREAT OF PRECIP TO THE SIERRA CASCADE RANGE BUT NORTHERLY FLOW ALOFT SHOULD END THREAT ELSEWHERE. SHOULD SEE CLEARING SKIES BY THURSDAY AFTERNOON WITH WARMER TEMPERATURES ALTHOUGH STILL WELL BELOW NORMAL FOR THIS TIME OF YEAR. STILL MORE WARMING EXPECTED ON FRIDAY AS FAIRLY FLAT UPPER RIDGE SLIDES OVER REGION BUT HIGH TEMPS STILL FORECAST TO REMAIN A LITTLE BELOW NORMAL. A SERIES OF WEATHER SYSTEMS PASSING WELL TO THE NORTH OF THE AREA WILL KEEP RIDGING OVER THE SOUTHWEST U.S. SUPPRESSED. THIS WILL HELP KEEP DAYTIME HIGHS FROM SATURDAY THROUGH THE MIDDLE OF NEXT WEEK FROM CLIMBING SIGNIFICANTLY SO EXPECTING TEMPERATURES THROUGH EXTENDED PERIOD TO REMAIN BELOW NORMAL. EXTENDED MODELS HINTING AT TROUGHING ALONG THE WEST COAST TOWARDS THE END OF NEXT WEEK AND EVEN SUGGESTING PRECIP THREAT BUT THIS WOULD BE BEYOND CURRENT FORECAST PERIOD AND RUN TO RUN CONSISTENCY IN THIS TIME FRAME HAS BEEN NOT BEEN GOOD WITH STRENGTH OF THIS SYSTEM. .AVIATION... CDFNT MOVS S OVR NORCAL THIS MRNG FLWD BY ASSOCD UPR TROF TDA INTO TNGT. MNLY VFR CONDS OVR INTR NORCAL NXT 24 HRS EXC LCL MVFR/IFR CIGS MNLY OMTNS EXC LCL IFR/LIFR IN ST VCNTY OF DELTA INTO PTNS OF SRN SAC VLY TIL 18Z. MDT/SVR ICGIC VCNTY CDFNT. WLY FLOW ALF VRG TO NLY TNGT. LCL SW-W SFC WND GSTS TO 25 KTS THRU DELTA AND INTO PTNS OF CNTRL VLY AND TO 30-35 KTS OVR HYR MTN TRRN TIL 04Z THU. && .STO WATCHES/WARNINGS/ADVISORIES...NONE. && $$
FXUS66 KSTO 081117 AFDSTO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 330 AM PDT WED SEP 8 2010 .DISCUSSION... COLD FOR THE SEASON UPPER LOW NOW CENTERED NEAR THE OREGON/WASHINGTON STATE BORDER WITH A SHORTWAVE TROUGH ROTATING AROUND SOUTHERN PORTION OF LOW AND THROUGH NORCAL AT THIS TIME. RADAR HAS BEEN PICKING UP LIGHT ECHOS ACROSS THE NORTHERN HALF OF THE CWA MOST OF THE EVENING BUT SO FAR NO REPORTS OF ANY PRECIP HITTING THE GROUND. UPPER LOW WILL BRING SIGNIFICANT AIRMASS COOLING TODAY AS IT DROPS SOUTHWARD. OVER THE SOUTHERN CWA MOUNTAINS WHERE CLOUDINESS FROM THE SHORTWAVE HAS NOT REACHED...TEMPERATURES ARE RUNNING FROM 10 TO 15 DEGREES BELOW 24 HOURS AGO. OVER THE NORTHERN CWA CLOUD COVER IS KEEPING TEMPERATURES WARMER THIS MORNING. FORT ORD PROFILER INDICATING A SIGNIFICANT INCREASE IN MARINE LAYER OVER THE LAST SEVERAL HOURS AS IT RESPONDS TO THE APPROACHING LOW AND PATCHY STRATUS APPEARS TO HAVE MADE IT INTO THE SOUTHERN SACRAMENTO VALLEY. COMBINATION OF CLOUDS AND COOLER AIRMASS WILL LIKELY KEEP TEMPERATURES IN THE CENTRAL VALLEY IN THE 70S TODAY. AT THIS TIME NO RECORD LOW MAXES ARE PREDICTED BUT TEMPERATURES IN MANY SACRAMENTO VALLEY LOCATIONS HAVE NOT SEEN HIGH TEMPERATURES THIS LOW SINCE MAY. ANOTHER SHORTWAVE TROUGH PIVOTING AROUND THE BACKSIDE OF THE LOW AND NOW OFF THE NORCAL COAST WILL DIG INTO NORCAL THIS AFTERNOON BRINGING INCREASED INSTABILITY AND AN INCREASED CHANCE OF SHOWERS TO MUCH OF THE AREA. PRECIPITATION AMOUNTS ARE STILL EXPECTED TO BE FAIRLY LIGHT AND GENERALLY UNDER 1/4 INCH. INSTABILITY PROGS SHOW THE BEST THREAT OF AFTERNOON THUNDERSTORMS WILL BE OVER THE HIGHER TERRAIN WITH LITTLE THREAT OF THUNDERSTORMS IN THE VALLEY. MAIN UPPER TROUGH FORECAST TO SWING EAST OF THE FORECAST AREA TONIGHT AND THURSDAY MORNING. SHORTWAVES DIGGING DOWN BACK SIDE OF THIS LOW COULD BRING THREAT OF PRECIP TO THE SIERRA CASCADE RANGE BUT NORTHERLY FLOW ALOFT SHOULD END THREAT ELSEWHERE. SHOULD SEE CLEARING SKIES BY THURSDAY AFTERNOON WITH WARMER TEMPERATURES ALTHOUGH STILL WELL BELOW NORMAL FOR THIS TIME OF YEAR. STILL MORE WARMING EXPECTED ON FRIDAY AS FAIRLY FLAT UPPER RIDGE SLIDES OVER REGION BUT HIGH TEMPS STILL FORECAST TO REMAIN A LITTLE BELOW NORMAL. A SERIES OF WEATHER SYSTEMS PASSING WELL TO THE NORTH OF THE AREA WILL KEEP RIDGING OVER THE SOUTHWEST U.S. SUPPRESSED. THIS WILL HELP KEEP DAYTIME HIGHS FROM SATURDAY THROUGH THE MIDDLE OF NEXT WEEK FROM CLIMBING SIGNIFICANTLY SO EXPECTING TEMPERATURES THROUGH EXTENDED PERIOD TO REMAIN BELOW NORMAL. EXTENDED MODELS HINTING AT TROUGHING ALONG THE WEST COAST TOWARDS THE END OF NEXT WEEK AND EVEN SUGGESTING PRECIP THREAT BUT THIS WOULD BE BEYOND CURRENT FORECAST PERIOD AND RUN TO RUN CONSISTENCY IN THIS TIME FRAME HAS BEEN NOT BEEN GOOD WITH STRENGTH OF THIS SYSTEM. .AVIATION... DFNT MOVS S OVR NORCAL THIS MRNG FLWD BY ASSOCD UPR TROF TDA INTO TNGT. MNLY VFR CONDS OVR INTR NORCAL NXT 24 HRS EXC LCL MVFR/IFR CIGS MNLY OMTNS EXC AREAS IFR/LIFR IN ST VCNTY OF DELTA INTO PTNS OF SRN SAC VLY TIL 18Z. MDT/SVR ICGIC VCNTY CDFNT. WLY FLOW ALF VRG TO NLY TNGT. LCL SW-W SFC WND GSTS TO 25 KTS THRU DELTA AND INTO PTNS OF CNTRL VLY AND TO 30-35 KTS OVR HYR MTN TRRN TIL 04Z THU. && .STO WATCHES/WARNINGS/ADVISORIES...NONE. && $$
FXUS66 KSTO 080537 AFDSTO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 1030 PM PDT TUE SEP 7 2010 .DISCUSSION... MUCH COOLER DAY ON TUE THAN 24 HRS AGO AS THE UPPER LEVEL TROF APPROACHED THE AREA AND INCREASED ONSHORE GRADIENTS. GENERALLY THERE WAS ABOUT 5 TO 8 DEG OF COOLING WITH 13 TO 25 DEG OF COOLING THROUGH THE CARQUINEZ STRAIT AND DELTA INFLUENCED AREAS. THE DELTA BREEZE WAS RESPONSIBLE FOR ABOUT 10 DEG OF COOLING IN THE SAC AREA IF THE BREEZE HAD NOT DEVELOPED...QUITE THE NATURAL AIR-CONDITIONER. FOR THIS EVENING...A BAND OF HIGHER LEVEL CLOUDS ARE RAPIDLY DROPPING SEWD WITH THE LEADING EDGE PASSING THROUGH THE I-80 CORRIDOR AS THE UPPER LEVEL TROF DEEPENS OVER NORCAL. MODEL RH PROGS SUGGEST THAT THE BOUNDARY LAYER WILL MOISTEN AS CYCLONIC FLOW AND LARGE SCALE ASCENT INCREASE OVERNITE. THE LOCAL STRATUS SCHEME CAME OUT POSITIVE FOR STRATUS FOR WED MORNING...FOLLOWING THE CLASS 2C SCENARIO OF THE MARINE AIR PENETRATION MODEL DOCUMENTED BY SAVAGE (1967). THE KEY ELEMENTS IN THE CLASS 2C ARE UP VALLEY PRESSURE GRADIENTS AFTER SUNSET WHICH CONTINUES MARINE FLOW INTO THE VALLEY...DEVELOPING LOW PRESSURE TO THE N AND E...AND A DEEPENING UPPER TROF AND MARINE LAYER. THIS CLASS DEVELOPS INTO A FULL BLOWN MARINE PENETRATION BY EARLY MORNING. AS THE TROF MOVES INLAND ON WED...SYNOPTIC COOLING OF SOME 11 DEG C AT 850 MBS AND 18 DAM THICKNESSES WILL RESULT IN A MUCH COOLER DAY THAN TODAY. MAX TEMPS WILL LIKELY RANGE FROM THE 60S IN THE CARQUINEZ TO MID 70S IN THE VLY...50S AND 60S IN THE FOOTHILLS AND MTNS. THE CAA AND STRONG CYCLONIC FLOW WILL ALSO RESULT IN INSTABILITY SHOWERS AND POSSIBLE T-STORMS MAINLY IN THE MTNS AND W SLOPE SIERNEV ON WED AND WED EVENING. LOOKS LIKE THE LATER MODEL RUNS ARE SHOWING MORE DIGGING OF THE VORT MAX NEAR THE BASE OF THE UPPER TROF WHICH SLOWS DOWN THE EWD PROGRESSION OF THE TROF AXIS FROM EARLIER RUNS. SHOWERS MAY LAST INTO THU MORNING OVER THE SIERNEV UNDER THIS SCENARIO. JHM .PREVIOUS DISCUSSION... PACIFIC NORTHWEST TROUGH CONTINUES TO AMPLIFY ALONG THE WEST COAST. WATER VAPOR SATELLITE IMAGERY SHOWS THE PRIMARY CIRCULATION RIGHT ALONG THE WASHINGTON COAST WITH MULTIPLE VORTICES ROTATING AROUND THE PRIMARY LOW. MID TO HIGH LEVEL CLOUDS CONTINUE TO SPREAD SOUTHWARD AHEAD OF THE COLD FRONT. THE MARINE LAYER CONTINUES TO DEEPEN AHEAD OF THE FRONT...UP TO AROUND 2700 FT AT FORT ORD. MARINE STRATUS INTRUSION IS A DIFFICULT FORECAST TONIGHT...AS A DEEP MARINE LAYER AND STRONG ONSHORE GRADIENT COULD POTENTIALLY BE OFFSET BY INCREASING CLOUD COVER AND TURBULENT MIXING. HAVE BEEN SEEING PERIODS OF LOCALLY GUSTY WINDS...TO AROUND 20-25 MPH THROUGH THE VALLEY AND UP TO AROUND 40-45 MPH TOWARDS THE SIERRA RIDGETOPS. WITH SYNOPTIC COOLING AND STRONGER MARINE INFLUENCE TEMPERATURES ARE RUNNING ANYWHERE FROM 4 TO 12 DEGREES COOLER THAN YESTERDAY ACROSS THE FORECAST AREA... AND 12 TO 20 DEGREES COOLER CLOSER TO THE DELTA. UPPER TROUGH CONTINUES TO DIG INTO NORTHERN CALIFORNIA TONIGHT INTO TOMORROW. WHILE WE COULD POTENTIALLY SEE A FEW LIGHT SHOWERS DEVELOP AS EARLY AS MIDNIGHT TONIGHT ALONG THE NORTHERN MOUNTAINS...MOST OF THE PRECIPITATION WILL HOLD OFF UNTIL WEDNESDAY. THE LATEST CROP OF MODEL RUNS HAVE TRENDED THE EXTENT OF PRECIPITATION FURTHER SOUTHWARD...WHICH SEEMS REASONABLE GIVEN HOW FAR SOUTH THE JET ENERGY DIVES. HAVE INTRODUCED A SLIGHT CHANCE OF SHOWERS IN THE VALLEY AS FAR SOUTH AS THE I-80/HIGHWAY 50 CORRIDOR...INCLUDING THE SACRAMENTO METRO AREA. WITH THE ANOMALOUS NATURE OF THIS SYSTEM...TEMPERATURES WILL CERTAINLY BE ON THE COOL END OF THE SPECTRUM. EXPECT VALLEY HIGHS TO REACH ONLY THE 70S THROUGH THE VALLEY WITH 50S AND 60S OVER THE MOUNTAINS. THE UPPER TROUGH WILL SHIFT EASTWARD INTO THE GREAT BASIN LATE WEDNESDAY INTO THURSDAY. DRIER NORTHWESTERLY FLOW WILL TAKE HOLD OVER THE FORECAST AREA...THOUGH CANT RULE OUT A FEW WRAPAROUND SHOWERS OVER THE MOUNTAINS THROUGH THURSDAY. WHILE THURSDAYS HIGHS WILL BE WARMER THAN WEDNESDAY...COLD AIR ADVECTION WILL KEEP TEMPS UNSEASONABLY COOL. SHOULD SEE MORE WARMING ON FRIDAY AS THE TROUGH SHIFTS EASTWARD AND IS REPLACED BY A MORE ZONAL FLOW. DANG .EXTENDED DISCUSSION (SATURDAY THROUGH TUESDAY)... A SERIES OF SYSTEMS WILL MOVE ONTO THE WEST COAST OVER THE WEEKEND AND INTO NEXT WEEK. THIS WILL KEEP TEMPERATURES NEAR TO A LITTLE BELOW NORMAL FOR THIS TIME OF YEAR. THERE IS SOME UNCERTAINTY IN THE TIMING AND TRACK OF THESE SYSTEMS. THE FIRST TROUGH MAY MOVE INTO WESTERN CANADA AND THE PACIFIC NORTHWEST OVER THE WEEKEND BUT LOOKS DRY. THE NEXT SYSTEM IS OVER THE EASTERN PACIFIC EARLY NEXT WEEK AND MAY MOVE INLAND MID WEEK. THIS SYSTEM LOOKS LIKE IT WILL BE STRONGER AND FURTHER SOUTH POSSIBLY BRINGING A THREAT OF PRECIPITATION MID TO LATE NEXT WEEK. .AVIATION... UPPER LEVEL TROUGH WILL MOVE INTO THE AREA TONIGHT INTO WEDNESDAY BRINGING MORE CLOUDS AND LOWER CEILINGS ALONG WITH GUSTY SOUTHWEST WINDS AND A THREAT OF PRECIPITATION (MAINLY NORTH OF HIGHWAY 50). AREAS OF MVFR CONDITIONS AND LOCAL IFR CONDITIONS ARE EXPECTED IN THE SACRAMENTO VALLEY AND MVFR CONDITIONS WITH AREAS OF IFR/LIFR CONDITIONS IN THE MOUNTAINS AFTER 10Z. SOUTHWEST WINDS OF 15-25KTS WITH GUSTS UP TO 35KTS NEAR THE CARQUINEZ STRAIT WITH ONSHORE FLOW. SOUTHWEST WIND GUSTS UP TO 40 KTS OVER THE MOUNTAINS. && .STO WATCHES/WARNINGS/ADVISORIES...NONE. && $$
FXUS66 KSTO 072300 AFDSTO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 400 PM PDT TUE SEP 7 2010 .DISCUSSION... PACIFIC NORTHWEST TROUGH CONTINUES TO AMPLIFY ALONG THE WEST COAST. WATER VAPOR SATELLITE IMAGERY SHOWS THE PRIMARY CIRCULATION RIGHT ALONG THE WASHINGTON COAST WITH MULTIPLE VORTICES ROTATING AROUND THE PRIMARY LOW. MID TO HIGH LEVEL CLOUDS CONTINUE TO SPREAD SOUTHWARD AHEAD OF THE COLD FRONT. THE MARINE LAYER CONTINUES TO DEEPEN AHEAD OF THE FRONT...UP TO AROUND 2700 FT AT FORT ORD. MARINE STRATUS INTRUSION IS A DIFFICULT FORECAST TONIGHT...AS A DEEP MARINE LAYER AND STRONG ONSHORE GRADIENT COULD POTENTIALLY BE OFFSET BY INCREASING CLOUD COVER AND TURBULENT MIXING. HAVE BEEN SEEING PERIODS OF LOCALLY GUSTY WINDS...TO AROUND 20-25 MPH THROUGH THE VALLEY AND UP TO AROUND 40-45 MPH TOWARDS THE SIERRA RIDGETOPS. WITH SYNOPTIC COOLING AND STRONGER MARINE INFLUENCE TEMPERATURES ARE RUNNING ANYWHERE FROM 4 TO 12 DEGREES COOLER THAN YESTERDAY ACROSS THE FORECAST AREA... AND 12 TO 20 DEGREES COOLER CLOSER TO THE DELTA. UPPER TROUGH CONTINUES TO DIG INTO NORTHERN CALIFORNIA TONIGHT INTO TOMORROW. WHILE WE COULD POTENTIALLY SEE A FEW LIGHT SHOWERS DEVELOP AS EARLY AS MIDNIGHT TONIGHT ALONG THE NORTHERN MOUNTAINS...MOST OF THE PRECIPITATION WILL HOLD OFF UNTIL WEDNESDAY. THE LATEST CROP OF MODEL RUNS HAVE TRENDED THE EXTENT OF PRECIPITATION FURTHER SOUTHWARD...WHICH SEEMS REASONABLE GIVEN HOW FAR SOUTH THE JET ENERGY DIVES. HAVE INTRODUCED A SLIGHT CHANCE OF SHOWERS IN THE VALLEY AS FAR SOUTH AS THE I-80/HIGHWAY 50 CORRIDOR...INCLUDING THE SACRAMENTO METRO AREA. WITH THE ANOMALOUS NATURE OF THIS SYSTEM...TEMPERATURES WILL CERTAINLY BE ON THE COOL END OF THE SPECTRUM. EXPECT VALLEY HIGHS TO REACH ONLY THE 70S THROUGH THE VALLEY WITH 50S AND 60S OVER THE MOUNTAINS. THE UPPER TROUGH WILL SHIFT EASTWARD INTO THE GREAT BASIN LATE WEDNESDAY INTO THURSDAY. DRIER NORTHWESTERLY FLOW WILL TAKE HOLD OVER THE FORECAST AREA...THOUGH CANT RULE OUT A FEW WRAPAROUND SHOWERS OVER THE MOUNTAINS THROUGH THURSDAY. WHILE THURSDAYS HIGHS WILL BE WARMER THAN WEDNESDAY...COLD AIR ADVECTION WILL KEEP TEMPS UNSEASONABLY COOL. SHOULD SEE MORE WARMING ON FRIDAY AS THE TROUGH SHIFTS EASTWARD AND IS REPLACED BY A MORE ZONAL FLOW. DANG .EXTENDED DISCUSSION (SATURDAY THROUGH TUESDAY)... A SERIES OF SYSTEMS WILL MOVE ONTO THE WEST COAST OVER THE WEEKEND AND INTO NEXT WEEK. THIS WILL KEEP TEMPERATURES NEAR TO A LITTLE BELOW NORMAL FOR THIS TIME OF YEAR. THERE IS SOME UNCERTAINTY IN THE TIMING AND TRACK OF THESE SYSTEMS. THE FIRST TROUGH MAY MOVE INTO WESTERN CANADA AND THE PACIFIC NORTHWEST OVER THE WEEKEND BUT LOOKS DRY. THE NEXT SYSTEM IS OVER THE EASTERN PACIFIC EARLY NEXT WEEK AND MAY MOVE INLAND MID WEEK. THIS SYSTEM LOOKS LIKE IT WILL BE STRONGER AND FURTHER SOUTH POSSIBLY BRINGING A THREAT OF PRECIPITATION MID TO LATE NEXT WEEK. .AVIATION... UPPER LEVEL TROUGH WILL MOVE INTO THE AREA TONIGHT INTO WEDNESDAY BRINGING MORE CLOUDS AND LOWER CEILINGS ALONG WITH GUSTY SOUTHWEST WINDS AND A THREAT OF PRECIPITATION (MAINLY NORTH OF HIGHWAY 50). AREAS OF MVFR CONDITIONS AND LOCAL IFR CONDITIONS ARE EXPECTED IN THE SACRAMENTO VALLEY AND MVFR CONDITIONS WITH AREAS OF IFR/LIFR CONDITIONS IN THE MOUNTAINS AFTER 10Z. SOUTHWEST WINDS OF 15-25KTS WITH GUSTS UP TO 35KTS NEAR THE CARQUINEZ STRAIT WITH ONSHORE FLOW. SOUTHWEST WIND GUSTS UP TO 40 KTS OVER THE MOUNTAINS. && .STO WATCHES/WARNINGS/ADVISORIES...NONE. && $$
FXUS66 KSTO 071605 AFDSTO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 905 AM PDT TUE SEP 7 2010 .DISCUSSION... UPPER RIDGE THAT BROUGHT THE LAST FEW DAYS OF WARM WEATHER HAS BEEN FLATTENED BY AN AMPLIFYING TROUGH ALONG THE WEST COAST. WATER VAPOR SATELLITE IMAGERY CLEARLY SHOWS THE PRIMARY CIRCULATION CURRENTLY OFF THE WASHINGTON COAST WITH MULTIPLE VORTICES ROTATING AROUND THE PRIMARY LOW. THE SOUTHERN EXTENT OF THE CIRRUS SHIELD IS NOW BRUSHING ACROSS FAR NORTHERN CALIFORNIA NEAR THE OREGON BORDER. WITH THE WEATHER PATTERN NOW CLEARLY AN ONSHORE REGIME...MARINE STRATUS HAS REBUILT ALONG THE COAST AND PUSHED INLAND AS FAR AS CORDELIA THIS MORNING. THE MARINE LAYER HAS RAPIDLY DEEPENED TO NEAR 2000 FT PER FORT ORD PROFILER. WITH THIS ONSHORE PATTERN MOST AREAS ARE RUNNING SEVERAL DEGREES COOLER THAN 24 HOURS AGO...MOST NOTICEABLY TOWARDS THE NORTHERN SAC VALLEY. WITH THE COMBINATION OF SYNOPTIC COOLING, STRONGER MARINE INFLUENCE AND GRADUALLY INCREASING HIGH CLOUD COVER...TODAYS HIGHS SHOULD BE ON THE ORDER OF 5 TO 10 DEGREES COOLER THAN YESTERDAY. WINDS WILL ALSO BE ON THE INCREASE TODAY AHEAD OF THE COLD FRONT...SIERRA RIDGETOP GUSTS COULD BE IN EXCESS OF 40 MPH THIS AFTERNOON. UPPER TROUGH CONTINUES TO DIG INTO NORTHERN CALIFORNIA TONIGHT INTO TOMORROW. WHILE WE COULD POTENTIALLY SEE A FEW LIGHT SHOWERS DEVELOP AS EARLY AS MIDNIGHT TONIGHT ALONG THE NORTHERN MOUNTAINS...MOST OF THE PRECIPITATION WILL HOLD OFF UNTIL WEDNESDAY. THE LATEST CROP OF MODEL RUNS HAVE TRENDED THE EXTENT OF PRECIPITATION FURTHER SOUTHWARD...WHICH SEEMS REASONABLE GIVEN HOW FAR SOUTH THE JET ENERGY DIVES. WILL RE-EVALUATE OUR PRECIPITATION FORECAST WITH THE AFTERNOON PACKAGE WITH THIS SYSTEM. WITH THE ANOMALOUS NATURE OF THIS SYSTEM...TEMPERATURES WILL CERTAINLY BE ON THE COOL END OF THE SPECTRUM. EXPECT VALLEY HIGHS TO REACH ONLY THE 70S THROUGH THE VALLEY WITH 50S AND 60S OVER THE MOUNTAINS. WITH THESE FORECAST NUMBERS...WE COULD APPROACH RECORD MINIMUM HIGH TEMPERATURE VALUES. THE UPPER TROUGH WILL SHIFT EASTWARD INTO THE GREAT BASIN LATE WEDNESDAY INTO THURSDAY. DRIER NORTHWESTERLY FLOW WILL TAKE HOLD OVER THE FORECAST AREA...THOUGH CANT RULE OUT A FEW WRAPAROUND SHOWERS OVER THE MOUNTAINS THROUGH THURSDAY. WHILE THURSDAYS HIGHS WILL BE WARMER THAN WEDNESDAY...COLD AIR ADVECTION WILL KEEP TEMPS UNSEASONABLY COOL. DANG .PREVIOUS DISCUSSION... WEAK UPPER RIDGING BEGINS TO BUILD OVER THE REGION BY FRIDAY BRINGING WARMER DAYTIME TEMPERATURES BUT STILL SEVERAL DEGREES BELOW NORMAL. SYSTEMS PASSING TO THE NORTH WILL KEEP SOUTHWEST U.S. RIDGE FROM BUILDING MUCH THROUGH THE EXTENDED PERIOD SO TEMPERATURES ARE EXPECTED TO REMAIN A LITTLE BELOW NORMAL THROUGH NEXT MONDAY. && .AVIATION... VFR CONDITIONS WILL CONTINUE THROUGH TODAY AND INTO TONIGHT. AN UPPER LEVEL TROUGH WILL SPREAD GRADUALLY THICKENING HIGH AND MID LEVEL CLOUDS THIS AFTERNOON AND EVENING OVER THE NORTHERN MOUNTAINS AND NORTHERN SACRAMENTO VALLEY. SOUTHWEST WINDS WILL INCREASE THIS AFTERNOON TO AROUND 10-15KT OVER THE CENTRAL VALLEY. SOUTHWEST GUSTS TO 35 KT ARE POSSIBLE OVER THE STRAIT OF CARQUINEZ FROM 18Z-04Z. SOUTHWEST GUSTS TO 40 KT ARE POSSIBLE OVER HIGHER MOUNTAIN RIDGES THIS AFTERNOON AND EVENING. EK && .STO WATCHES/WARNINGS/ADVISORIES...NONE. && $$
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