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. 
 
 &&
 
 $$

  NWS STO Office Area Forecast Discussion
  

   
 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. 
 
 &&
 
 $$

  NWS STO Office Area Forecast Discussion
  

   
 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. 
 
 &&
 
 $$

  NWS STO Office Area Forecast Discussion
  

   
 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. 
 
 &&
 
 $$

  NWS STO Office Area Forecast Discussion
  

   
 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. 
 
 &&
 
 $$

  NWS STO Office Area Forecast Discussion
  

   
 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. 
 
 &&
 
 $$

  NWS STO Office Area Forecast Discussion
  

   
 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. 
 
 &&
 
 $$

  NWS STO Office Area Forecast Discussion
  

   
 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. 
 
 &&
 
 $$

  NWS STO Office Area Forecast Discussion
  

   
 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. 
 
 &&
 
 $$

  NWS STO Office Area Forecast Discussion
  

   
 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. 
 
 &&
 
 $$

  NWS STO Office Area Forecast Discussion
  

   
 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. 
 
 &&
 
 $$

  NWS STO Office Area Forecast Discussion