FXUS66 KSTO 171647
 AFDSTO
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SACRAMENTO CA
 945 AM PDT THU MAY 17 2012
 
 .SHORT TERM DISCUSSION...
 
 MUCH COOLER DAY OVER INTERIOR NORCAL TODAY AS UPPER-LEVEL PACIFIC 
 TROF MOVES INLAND AND ACROSS NORCAL THRU TONITE. ONSHORE GRADIENTS 
 HAVE BEEN INCREASING AND SYNOPTIC COOLING AND DELTA BREEZE WILL 
 BEGIN TO COOL THE AIR MASS MORE AS THE DAY WEARS ON. THE 24-HR TEMP 
 CHANGE IS JUST BEGINNING TO SHOW SOME COOLING AT PRESS TIME...WITH 
 850 MBS TEMPS AND LOW TO MID LEVEL THICKNESSES SUGGESTING AT LEAST 
 SOME 4 TO 11 DEG OF COOLING OVER MOST OF THE AREA. OUR MAX TEMP 
 CHANGE GRID SHOWS THE EQUIVALENT...SOME 3 TO 13 DEG OF COOLING 
 TODAY. 
 
 CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS STILL LOOK POSSIBLE 
 MAINLY OVER OUR NERN ZONES PER THE PREVIOUS DISCUSSION. THE SPC 
 12-HR PROB OF TSTORMS SHOWS ABOUT A 1 IN 5 CHANCE OVER THE NRN 
 SIERNEV MAINLY N OF THE TAHOE AREA THIS AFTERNOON AND TONITE. THIS 
 IS IN LINE WITH THE MODEL CAPE/INSTABILITY FORECASTS. THE NAM/WRF 
 SURFACE BOUNDARY ASSOCIATED WITH UPPER TROF SHOWS A MODEST 
 CONVERGENCE ZONE MOVING FROM THE SHASTA CO MTNS SEWD TOWARDS THE 
 I-80 CORRIDOR BY LATE THIS EVENING...AND THEN SE OF OUR AREA FRI 
 MORNING. WINDS WILL TURN NWLY BEHIND THE BOUNDARY TONIGHT AND FRI 
 MORNING. BEST CHANCE OF TSTORMS THIS AFTERNOON AND EVENING IS 
 EXPECTED TO BE IN THE PROXIMITY OF THE SURFACE BOUNDARY/CONVERGENCE 
 ZONE.    JHM 
 
 
 .PREVIOUS DISCUSSION... 
 
 PRETTY GOOD AGREEMENT IN ALL MODELS THAT A FAIRLY WELL DEFINED
 COOL FRONT ASSOCIATED WITH UPPER WAVE WILL PUSH ACROSS THE AREA THIS
 AFTERNOON. NAM PICKING UP ON PRETTY GOOD 700 MB FRONTOGENESIS AND
 SURFACE CONVERGENCE LINE PUSHING FROM NORTH TO SOUTH ACROSS THE
 AREA THIS AFTERNOON. INSTABILITY FORECAST FROM LOCAL WRF MODEL
 PRETTY HIGH AND LOOKS OVERDONE WITH LOW LEVELS PRETTY DRY WITH
 THIS SYSTEM. NAM/GFS HAVE BEEN CONSISTENT AND HAVE PICKED UP ON AN
 AREA OF CAPE OF AROUND 400 J/KG TO BE IN PLACE IN PLUMAS AND
 SIERRA COUNTY THIS AFTERNOON AS FRONT PUSHES THROUGH. THIS IS
 WHERE THERE SHOULD BE A FEW SHOWERS AND THUNDERSTORMS. NAM ALSO
 PLACING SOME INSTABILITY AND LIFT ON THE WEST SIDE OF THE VALLEY IN
 LAKE COUNTY SO HAVE ADDED SOME SLIGHT CHANCES THERE FOR THIS
 AFTERNOON AND EVENING. SREF PROBABILITIES ALSO IN LINE WITH LOWER
 INSTABILITY SHOWING ONLY A SLIGHT CHANCE OF CAPE OVER 500 J/KG
 ANYWHERE TODAY. OVER THE VALLEY WITH DRY LOW LEVELS SHOULD BE
 ANYTHING MORE THAN CLOUDS AND MAYBE A SPRINKLE. EXPECT BREEZY
 CONDITIONS IN THE DELTA WITH CONTINUED ONSHORE FLOW AND STILL
 THINK WE COULD SEE SOME STRATUS INTRUDE INTO VALLEY LATER THIS
 MORNING.
 
 ON FRIDAY...THE SYSTEM MOVES QUICKLY OFF TO THE EAST AND WE SHOULD 
 SEE A LITTLE NORTHERLY WIND...BUT NOTHING TOO BAD. TEMPERATURES 
 SHOULD MODERATE BUT WEATHER WILL BE DRY.
 
 SATURDAY AND SUNDAY...HIGHER HEIGHTS BUILD INTO THE AREA SATURDAY BUT
 TROUGH BEGINS TO MOVE ONTO WEST COAST SHORE SUNDAY EVENING. AHEAD
 OF IT GOOD TEMPERATURE WARM UP THOUGH AND SUNDAY LOOKS PRETTY WARM
 IN THE 90S...AND SHOULD BE THE WARMEST DAY FOR NEXT 7 DAYS. RASCH
 
 .EXTENDED DISCUSSION (MONDAY THROUGH THURSDAY)
 
 COOLER WEATHER WILL ARRIVE WITH THE NEW WORK WEEK ON MONDAY AS A
 TROUGH OF LOW PRESSURE MOVES OVER THE WEST COAST. MOST OF THE
 MOISTURE ASSOCIATED WITH THIS TROUGH WILL BE CARRIED NORTH OF THE
 AREA...THOUGH THE THREAT OF SOME SHOWERS IN THE NORTHERN
 MOUNTAINS EXISTS. THE TROUGH MOVES INLAND TUE AND HEIGHTS BEGIN TO
 RISE OVER THE EASTERN PACIFIC AS A RIDGE BUILDS. MODELS DIVERGE AS
 TO THE LOCATION AND TIMING OF FEATURES...BUT THE MAIN IDEA IS A
 COOLER START TO THE WEEK WITH A GENERALLY DRY PATTERN. DK
 
 
 &&
 
 .AVIATION...
 
 UPPER LEVEL TROF MOVING ACROSS NORTHERN CA TDA AND TONIGHT. ONSHORE 
 FLOW WILL LEAD TO COOLER TEMPS AND BREEZY WINDS IN THE VALLEY AND 
 WIND GUSTS TO 45-50 KTS OVER SIERNEV CREST. MAINLY VFR CONDITIONS 
 OVER INTERIOR NORCAL WITH BKN-OVC MID AND HIGH LEVEL CLOUDS UNTIL 
 TROF PASSES LATER TONITE. SCATTERED SHOWERS AND CHANCE OF 
 THUNDERSTORMS SPREADING FROM THE NRN MTNS INTO THE SIERNEV DURING 
 AFTERNOON AND EVENING WITH POSSIBLE MVFR CIGS/VSBYS OBSCG HIER TRRN. 
 
 &&
 
 .STO WATCHES/WARNINGS/ADVISORIES...NONE.
 
 &&
 
 $$


  NWS STO Office Area Forecast Discussion
  

   
 FXUS66 KSTO 171023
 AFDSTO
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SACRAMENTO CA
 323 AM PDT THU MAY 17 2012
 
 .SHORT TERM DISCUSSION...
 
 THINGS STILL ON TRACK FOR A PROGRESSIVE SYSTEM TO PUSH ACROSS THE
 AREA TODAY AND EARLY THIS EVENING. MAIN CHALLENGES ARE SHOWER AND
 THUNDERSTORM COVERAGE.
 
 PRETTY GOOD AGREEMENT IN ALL MODELS THAT A FAIRLY WELL DEFINED
 COOL FRONT ASSOCIATED WITH UPPER WAVE WILL PUSH ACROSS THE AREA THIS
 AFTERNOON. NAM PICKING UP ON PRETTY GOOD 700 MB FRONTOGENESIS AND
 SURFACE CONVERGENCE LINE PUSHING FROM NORTH TO SOUTH ACROSS THE
 AREA THIS AFTERNOON. INSTABILITY FORECST FROM LOCAL WRF MODEL
 PRETTY HIGH AND LOOKS OVERDONE WITH LOW LEVELS PRETTY DRY WITH
 THIS SYSTEM. NAM/GFS HAVE BEEN CONSISTENT AND HAVE PICKED UP ON AN
 AREA OF CAPE OF AROUND 400 J/KG TO BE IN PLACE IN PLUMAS AND
 SIERRA COUNTY THIS AFTERNOON AS FRONT PUSHES THROUGH. THIS IS
 WHERE THERE SHOULD BE A FEW SHOWERS AND THUNDERSTORMS. NAM ALSO
 PLACING SOME INSTABILITY AND LIFT ON THE WEST SIDE OF THE VALLEY IN
 LAKE COUNTY SO HAVE ADDED SOME SLIGHT CHACNES THERE FOR THIS
 AFTERNOON AND EVENING. SREF PROBABILITIES ALSO IN LINE WITH LOWER
 INSTABILITY SHOWING ONLY A SLIGHT CHANCE OF CAPE OVER 500 J/KG
 ANYWHERE TODAY. OVER THE VALLEY WITH DRY LOW LEVELS SHOULD BE
 ANYTHING MORE THAN CLOUDS AND MAYBE A SPRINKLE. EXPECT BREEZY
 CONDITIONS IN THE DELTA WITH CONTINUED ONSHORE FLOW AND STILL
 THINK WE COULD SEE SOME STRATUS INTRUDE INTO VALLEY LATER THIS
 MORNING.
 
 FRIDAY SYSTEM MOVES QUICKLY OFF TO THE EAST AND WE SHOULD SEE A
 LITTLE NORTHERLY WIND...BUT NOTHING TOO BAD. TEMPERATURES SHOULD
 MODERATE BUT WEATHER WILL BE DRY.
 
 SATURDAY AND SUNDAY...HIGHER HEIGHTS BUILD INTO AERA SATURDAY BUT
 TROUGH BEGINS TO MOVE ONTO WEST COAST SHORE SUNDAY EVENING. AHEAD
 OF IT GOOD TEMPERATURE WARM UP THOUGH AND SUNDAY LOOKS PRETTY WARM
 IN THE 90S...AND SHOULD BE THE WARMEST DAY FOR NEXT 7 DAYS. RASCH
 
 .EXTENDED DISCUSSION (MONDAY THROUGH THURSDAY)
 
 COOLER WEATHER WILL ARRIVE WITH THE NEW WORK WEEK ON MONDAY AS A
 TROUGH OF LOW PRESSURE MOVES OVER THE WEST COAST. MOST OF THE
 MOISTURE ASSOCIATED WITH THIS TROUGH WILL BE CARRIED NORTH OF THE
 AREA...THOUGH THE THREAT OF SOME SHOWERS IN THE NORTHERN
 MOUNTAINS EXISTS. THE TROUGH MOVES INLAND TUE AND HEIGHTS BEGIN TO
 RISE OVER THE EASTERN PACIFIC AS A RIDGE BUILDS. MODELS DIVERGE AS
 TO THE LOCATION AND TIMING OF FEATURES...BUT THE MAIN IDEA IS A
 COOLER START TO THE WEEK WITH A GENERALLY DRY PATTERN. DK
 
 
 &&
 
 .AVIATION...
 
 A TROUGH MOVES ACROSS NORTHERN CA THU AND THU NIGHT. MID AND HIGH LEVEL
 CLOUDS WILL DECREASE STRATUS DEVELOPMENT THU MORNING OVER THE
 INTERIOR AND DELTA REGION. EXPECT ONSHORE BREEZY CONDITIONS OVER
 DELTA WITH SW GUSTS TO 25 KTS ESPECIALLY IN THE AFTERNOON AND
 EARLY EVENING. CHANCE OF THUNDERSTORMS OVER THE SIERRA AND
 NORTHERN MOUNTAINS AFTER 18Z.
 
 &&
 
 .STO WATCHES/WARNINGS/ADVISORIES...
 NONE.
 &&
 
 $$


  NWS STO Office Area Forecast Discussion
  

   
 FXUS66 KSTO 170359
 AFDSTO
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SACRAMENTO CA
 859 PM PDT WED MAY 16 2012
 
 .SHORT TERM DISCUSSION...
 
 THE WINDS WILL BE STRONG AT TIMES TONIGHT THROUGH THE DELTA AS
 THE SYSTEM MOVES CLOSER TO COAST OVERNIGHT AND SHOULD CONTINUE TO
 BE AT LEAST MODERATE DURING THE DAY. HIGH CLOUDS WILL BEGIN TO
 SPREAD OVER THE INTERIOR LATER TONIGHT. THE MARINE LAYER ALONG THE
 COAST LOWERED THIS AFTERNOON ALONG THE COAST BUT IS NOW INCREASING
 AGAIN AS THE LOW MOVES CLOSER. SOME LOW CLOUDS WILL LIKELY ADVECT
 INTO THE INTERIOR THURSDAY MORNING DUE TO THE STRETCHING OF THE
 MARINE LAYER OVERNIGHT AND THE STRONG PUSH THROUGH THE DELTA.
 
 COOLING WILL THURSDAY OCCUR WITH HIGHS COOLING BACK INTO THE MID
 70S TO LOWER 80S FOR THE VALLEY...WITH THE COOLEST TEMPERATURES IN
 THE DELTA AND AREAS NEAR THE DELTA. A 70 TO 80KT JET WILL MOVE
 OVER THE SOUTHERN SACRAMENTO VALLEY THURSDAY MORNING AND PUSHES
 FURTHER SOUTH THAN YESTERDAYS MODEL RUNS. THIS WILL BRING SOME
 SHOWER AND THUNDERSTORM CHANCES MAINLY NORTH OF I-80 FOR THE
 MOUNTAINS WITH A SLIGHT CHANCE OF SOME ISOLATED ACTIVITY OVER THE
 NORTHERN HALF OF THE SACRAMENTO VALLEY. INSTABILITY DOES NOT LOOK
 ALL THAT GREAT WITH THIS SYSTEM SO EXPECT ANY THUNDERSTORMS THAT
 DO DEVELOP WOULD BE OVER HIGHER TERRAIN IN THE MOUNTAINS.
 
 THE TROUGH WILL MOVE EAST OF THE AREA ON FRIDAY TO ALLOW
 TEMPERATURES TO WARM UP BACK INTO THE 80S AND THE INTERIOR LOOSES
 IT THREAT OF ANY SHOWER OR THUNDERSTORM ACTIVITY. WEAK RIDGING
 WILL OCCUR ON SATURDAY AS ANOTHER TROUGH DEVELOPS OVER THE PACIFIC
 WITH SOME CONTINUED WARMING AND TEMPERATURES MAINLY IN THE MID TO
 UPPER 80S FOR THE VALLEY WITH MID 60S AND 70S IN THE MOUNTAINS.
 
 .EXTENDED DISCUSSION (SUNDAY THROUGH WEDNESDAY)
 
 CENTRAL VALLEY TEMPS WILL WARM FROM THE LATE WEEKEND TO EARLY
 NEXT WEEK IN RESPONSE TO BUILDING HEIGHTS OVER THE DISTRICT.
 COOLING IN RESPONSE TO AN APPROACHING TROUGH OF LOW PRESSURE
 DEVELOPS MON WITH THE ECMWF STRONGER AND MORE PROGRESSIVE WITH
 THIS FEATURE THAN GFS. HAVE LEANED TOWARD A BLEND OF BOTH FOR
 GENERAL COOLING AND STRONGER MARINE INFLUENCE AND ENHANCED DELTA
 BREEZES. STILL GENERALLY DRY AND SEASONAL TEMPERATURES MOST AREA
 EXCEPT SLIGHT CHANCES SHOWERS IN THE FAR NORTH MON THROUGH WED.
 DK2
 
 
 &&
 
 .AVIATION...
 
 WLY FLOW ALF AS UPR TROF APCHS TNGT THEN MOVS THRU INTR NORCAL THU 
 INTO THU NGT WITH FLOW ALF VRG NWLY AFT 00Z FRI. AREAS OF MVFR/IFR
 CONDS LIKELY IN PORTIONS OF DELTA AFT 08Z AND POSS INTO PTNS OF
 SRN SAC VLY BTWN 10Z- 18Z THU. OTRW MNLY VFR WITH SCT-BKN CLDS ABV
 FL120 NXT 24 HRS EXC ISOLD MVFR POSS IN SHWR OR TSTM OVR HYR TRRN
 OF SHASTA AND WRN PLUMAS MTNS AND SIERNEV BTWN 18Z-06Z. LCL SWLY
 SFC WND GSTS TO 25 KTS OR GTR THRU DELTA AND OVR HYR MTN TRRN TNGT
 INTO THU.
 
 &&
 
 .STO WATCHES/WARNINGS/ADVISORIES...NONE. 
 
 &&
 
 $$


  NWS STO Office Area Forecast Discussion
  

   
 FXUS66 KSTO 162215
 AFDSTO
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SACRAMENTO CA
 330 PM PDT WED MAY 16 2012
 
 .SHORT TERM DISCUSSION...
 VISIBLE SATELLITE IMAGERY SHOWING CLEAR SKIES OVER THE FORECAST AREA 
 THIS AFTERNOON UNDER WESTERN U.S. HIGH PRESSURE RIDGE. SOME CUMULUS 
 POPPING UP JUST NORTH OF SHASTA COUNTY AT THIS TIME AS A WEAK UPPER 
 DISTURBANCE SKIRTS THE CWA SO CAN NOT RULE OUT SLIGHT THREAT OF 
 SHOWERS OR THUNDERSTORMS OVER THE SHASTA COUNTY MOUNTAINS THIS 
 EVENING. OTHERWISE...SHOULD SEE SOME INCREASING HIGH CLOUDS OVER THE 
 AREA TONIGHT AS AN UPPER LEVEL TROUGH APPROACHES THE COAST. FORT ORD 
 PROFILER SHOWING MARINE LAYER AT AROUND 1000 FEET DEEP THIS 
 AFTERNOON BUT IT SHOULD BE DEEPENING THROUGH THE NIGHT AS TROUGH 
 APPROACHES. THEREFORE...SOME SCATTERED MARINE STRATUS MIGHT MAKE IT 
 INTO THE SACRAMENTO AREA LATE TONIGHT. 
 
 UPPER LEVEL TROUGH AXIS FORECAST TO BE NEAR THE COASTLINE BY 18Z 
 TOMORROW. THIS LATE SEASON PACIFIC SYSTEM WILL BRING IN INCREASED 
 MOISTURE ACROSS THE NORTHERN PORTIONS OF THE STATE AND SOME LIFT. 
 CONDITIONS NOT EXPECTED TO BE ALL THAT UNSTABLE HOWEVER SO ANY 
 THUNDERSTORM ACTIVITY IS LIKELY TO BE VERY ISOLATED. 1000 TO 500MB 
 THICKNESS COOLS ABOUT 10 DECAMETERS SO COOLER TEMPERATURES 
 DEFINITELY IN STORE FOR THURSDAY WITH AT LEAST SOME CLOUDINESS FOR 
 THE ENTIRE CWA. THE RIDGETOPS WILL SEE BREEZY SOUTHWEST WINDS AHEAD 
 OF THE TROUGH BUT WITH INCREASING HUMIDITY...SHOULD NOT SEE A 
 SIGNIFICANT INCREASE IN FIRE DANGER. UPPER THROUGH AXIS PROGRESSES 
 QUICKLY EASTWARD INTO NEVADA BY 12Z FRIDAY SO PRECIP THREAT ENDS. 
 MAY SEE A PERIOD OF BREEZY NORTH WINDS EARLY FRIDAY AS ABOUT A 9 MB 
 SURFACE GRADIENT DEVELOPS BETWEEN MFR AND SAC. THIS GRADIENT WEAKENS 
 QUICKLY WITH UPPER RIDGE PUSHING IN. DAYTIME HIGHS WARM GOING INTO 
 THE WEEKEND AS A SOMEWHAT FLAT UPPER RIDGE AXIS CENTERS OVER THE 
 WEST COAST. BY SATURDAY...DAYTIME HIGHS ARE FORECAST TO BE BACK 
 AROUND 5 DEGREES ABOVE NORMAL FOR THIS TIME OF YEAR. 
 
 .EXTENDED DISCUSSION (SUNDAY THROUGH WEDNESDAY)
 UPPER RIDGE SHIFTS EAST INTO THE INTERMOUNTAIN WEST SUNDAY AS UPPER 
 TROUGH APPROACHES. HIGH TEMPS SUNDAY IN THE CENTRAL VALLEY ARE 
 EXPECTED IN THE MID TO UPPER 80S. UPPER TROUGH MOVES THROUGH EARLY 
 NEXT WEEK WITH MODELS DIFFERING ON TIMING AND DEPTH OF THE WAVE. 
 OPER GFS SHOWING LESS VARIATION FROM RUN TO RUN COMPARED TO 
 ECMWF-HIRES AND GEM AND THUS FORECAST FOLLOWS THIS MODEL FOR NOW 
 WITH A SLIGHT CHANCE OF SHOWERS OVER THE SHASTA MOUNTAINS MONDAY. 
 MINOR SYNOPTIC COOLING EXPECTED FOR THE REMAINDER OF THE CWA WITH  
 INCREASED FLOW THROUGH DELTA MONDAY.
 
 QUASI-ZONAL FLOW SETS UP ACROSS THE EPAC TUESDAY INTO WEDNESDAY AS 
 EPAC RIDGE RETROGRADES AND NEXT SHORT WAVE MOVES INTO THE PAC NW.  
 THIS WILL PROVIDE A GRADUAL LOWERING OF HEIGHTS OVER INTERIOR NORCAL 
 RESULTING IN A SLOW DOWNWARD TREND IN TEMPS THROUGH MIDWEEK. CENTRAL 
 VALLEY HIGHS FORECAST IN MOSTLY THE LOWER 80S BY WEDNESDAY WITH 60S 
 TO 70S FOR THE FOOTHILLS AND MOUNTAINS.
 
 &&
 
 .AVIATION...
 WLY FLOW ALF AS UPR TROF APCHS TNGT THEN MOVS THRU INTR NORCAL THU 
 INTO THU NGT WITH FLOW ALF VRG NWLY AFT 00Z FRI. LCL MVFR/IFR CONDS 
 POSS IN ST VCNTY DELTA AND POSS INTO PTNS OF SRN SAC VLY BTWN 
 10Z-18Z THU. OTRW MNLY VFR WITH SCT-BKN CLDS ABV FL120 NXT 24 HRS 
 EXC ISOLD MVFR POSS IN SHWR OR TSTM OVR HYR TRRN OF SHASTA AND WRN 
 PLUMAS MTNS AND SIERNEV BTWN 18Z-06Z. LCL SWLY SFC WND GSTS TO 25 
 KTS OR GTR THRU DELTA AND OVR HYR MTN TRRN TNGT INTO THU.
  
 
 &&
 
 .STO WATCHES/WARNINGS/ADVISORIES...NONE.
 &&
 
 $$


  NWS STO Office Area Forecast Discussion
  

   
 FXUS66 KSTO 161634
 AFDSTO
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SACRAMENTO CA
 930 AM PDT WED MAY 16 2012
 
 .SHORT TERM DISCUSSION...
 CLEAR SKIES OVER THE CWA THIS MORNING UNDER UPPER LEVEL HIGH 
 PRESSURE. ONLY EXCEPTION THIS MORNING WAS IN THE DELTA REGION WHERE 
 SOME SCATTERED MARINE STRATUS MADE IT INLAND WITH A FEW CLOUDS EVEN 
 REPORTED AT SACRAMENTO EXECUTIVE AIRPORT. FORT ORD PROFILER SHOWING 
 MARINE LAYER DEPTH AT ABOUT 1800 FEET THIS MORNING. AS THE UPPER 
 LEVEL TROUGH NOW AT ABOUT 140 WEST APPROACHES THE COAST TOMORROW 
 ...MARINE LAYER WILL LIKELY DEEPEN SO WILL NEED TO WATCH FOR STRATUS 
 INTRUSION TONIGHT AND EARLY THURSDAY. OVERALL AIRMASS SHOULD BE A 
 LITTLE COOLER TODAY SO EXPECT TODAYS HIGHS TO COME IN NEAR OR LOWER 
 THAN TUESDAY AND MAY NEED TO UPDATE MAX TEMP FORECASTS TO BRING THEM 
 DOWN A LITTLE. ONLY OTHER ISSUE TODAY IS SLIGHT THREAT OF 
 THUNDERSTORMS OVER THE FAR NORTHERN MOUNTAINS. GFS/NAM BOTH SHOW 
 VERY MINOR DISTURBANCE TREKKING THROUGH FAR NORCAL EARLY THIS 
 EVENING. WITH ONLY A SLIGHT LIFT INCREASE AND STABILITY DECREASE AND 
 VERY LIMITED MOISTURE COMBINED WITH UPPER SOUTHWEST FLOW...BELIEVE 
 THIS THREAT IS VERY MINIMAL BUT NOT OUT OF THE QUESTION. THEREFORE 
 WILL LEAVE VERY SLIGHT T-STORM THREAT FOR NORTHERN MOUNTAINS IN 
 FORECAST FOR NOW. 
 
 UPPER LEVEL TROUGH AXIS FORECAST TO BE NEAR THE COASTLINE BY 18Z 
 TOMORROW. THIS LATE SEASON PACIFIC SYSTEM WILL BRING IN INCREASED 
 MOISTURE ACROSS THE NORTHERN PORTIONS OF THE STATE AND SOME LIFT. 
 CONDITIONS NOT EXPECTED TO BE ALL THAT UNSTABLE HOWEVER SO ANY 
 THUNDERSTORM ACTIVITY IS LIKELY TO BE VERY ISOLATED. 1000 TO 500MB 
 THICKNESS COOLS ABOUT 10 DECAMETERS SO COOLER TEMPERATURES 
 DEFINITELY IN STORE FOR THURSDAY WITH AT LEAST SOME CLOUDINESS FOR 
 THE ENTIRE CWA. UPPER THROUGH AXIS PROGRESSES QUICKLY EASTWARD INTO 
 NEVADA BY 12Z FRIDAY SO PRECIP THREAT ENDS. MAY SEE A PERIOD OF 
 BREEZY NORTH WINDS EARLY FRIDAY AS ABOUT A 9 MB SURFACE GRADIENT 
 DEVELOPS BETWEEN MFR AND SAC. THIS GRADIENT WEAKENS QUICKLY WITH 
 UPPER RIDGE PUSHING IN. DAYTIME HIGHS WARM GOING INTO THE WEEKEND AS 
 A SOMEWHAT FLAT UPPER RIDGE AXIS CENTERS OVER THE WEST COAST. 
 
 .EXTENDED DISCUSSION (SUNDAY THROUGH WEDNESDAY)
 
 LOOKS LIKE SUNDAY WILL BE THE WARMEST DAY OF THE WEEKEND WITH 
 DAYTIME HIGHS ABOUT 5 TO 10 DEGREES ABOVE SEASON NORMAL BEFORE UPPER 
 RIDGE BEGINS TO SLIP EASTWARD. EARLY NEXT WEEK WILL SEE COOLING IN 
 RESPONSE TO AN APPROACHING TROUGH OF LOW PRESSURE. ECMWF A LITTLE 
 FASTER WITH THIS SYSTEM THAN GFS WITH GEM BRINGING TROUGH THROUGH 
 NORCAL ABOUT A DAY LATER THAN EURO MODEL AND ALSO MUCH DEEPER. 
 CURRENT FORECAST LEANS TO GFS/ECMWF SOLUTIONS KEEPING PRECIP THREAT 
 LIMITED TO NORTHERN MOST ZONES. OTHERWISE...GENERAL COOLING AND 
 STRONGER MARINE INFLUENCE AND ENHANCED DELTA BREEZES THROUGH 
 REMAINDER OF EXTENDED PERIOD. 
 
 
 &&
 
 .AVIATION...
 
 A FEW LOW CLOUDS NEAR THE EASTERN SAN FRANCISCO BAY MAY SPREAD OVER 
 THE WESTERN DELTA REGION EARLY THU BUT WILL DISSIPATE BY 16Z. 
 OTHERWISE VFR TODAY AND TONIGHT. DELTA BREEZE CONDITIONS WITH LOCAL 
 SW GUSTS TO 30 KTS ARE POSSIBLE MAINLY AFTER 20Z. ISOLATED 
 THUNDERSTORMS MAY DEVELOP NORTH OF ABOUT MYV AFTER 18Z THURSDAY. 
 
 &&
 
 .STO WATCHES/WARNINGS/ADVISORIES...NONE.
 &&
 
 $$


  NWS STO Office Area Forecast Discussion
  

   
 FXUS66 KSTO 161045
 AFDSTO
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SACRAMENTO CA
 345 AM PDT WED MAY 16 2012
 
 .SHORT TERM DISCUSSION...
 
 NO MAJOR CHANGES TO FORECAST. BIGGEST CHALLENGE FOR THE SHORT TERM
 WAS PRECIPITATION FORECAST WITH THURSDAY WAVE AND INCREASING WINDS
 WITH THIS SYSTEM AS WELL.
 
 TODAY...SHOULDN`T BE TOO MUCH CHANGE IN TEMPERATURES AS UPPER FLOW
 REMAINS WESTERLY WITH LITTLE CHANGE IN HEIGHTS AND LOW LEVEL
 TEMPERATURES. MODELS ARE SHOWING ONLY SLIGHT INSTABILITY AND NAM
 ONLY A SMALL AMOUNT OF QPF LATE IN THE AFTERNOON IN NORTHERN
 AREAS. WAS TEMPTED TO REMOVE MENTION OF PRECIPITATION BUT SINCE
 THEY ARE SHOWING A SMALL INDICATION OF IT AND IT IS ALREADY IN THE
 FORECAST WILL LET IT RIDE AS IT IS ONLY A SLIGHT CHANCE.
 
 BETTER CHANCE OF MOISTURE WILL COME INTO PLAY THURSDAY AS
 PROGRESSIVE UPPER TROUGH SLIDES ACROSS THE AREA DURING THE DAY.
 MODELS LOOK TO BE TRENDING STRONGER WITH THIS SYSTEM BUT CONTINUE
 TO PLACE BEST LIFT AND INSTABILITY IN NORTHERN HALF OF FORECAST
 AREA. HOWEVER...THE LIFT AND INSTABILITY DON`T LOOK ALL THAT
 IMPRESSIVE AND THINK CURRENT ISOLATED TO LOW SCATTERED POPS LOOK
 LIKE A GOOD CALL. STILL DOESN`T LOOK TO BE A FIRE WEATHER CONCERN
 WITH LIMITED THUNDERSTORM COVERAGE. LOOKS LIKE A PRETTY GOOD
 ONSHORE FLOW WILL BE IN PLACE DURING MOST OF THE DAY. MIGHT SEE
 SOME STRATUS INTRUSION INTO SACRAMENTO AREA BUT SHOULDN`T BE A BIG
 IMPACT IF IT DOES BURNING OFF QUICKLY. SHOULD BE A BREEZY DAY
 ACROSS THE DELTA AS WELL. OVERALL ALL THIS WILL RESULT IN A COOLER
 DAY WITH TEMPERATURES IN THE UPPER 70S TO LOWER 80S. 
 
 FRIDAY AND SATURDAY TEMPERATURES WILL WARM AS PROGRESSIVE TROUGH
 PUSHES OFF TO THE EAST. UPPER FLOW REMAINS WESTERLY WITH LITTLE
 AMPLIFICATION TO THE FLOW. THIS WILL RESULT IN DRY WEATHER AND
 NEAR SEASONABLE TEMPERATURES. RASCH
 
 .EXTENDED DISCUSSION (SUNDAY THROUGH WEDNESDAY)
 
 CENTRAL VALLEY TEMPS WILL WARM FROM THE LATE WEEKEND TO EARLY
 NEXT WEEK IN RESPONSE TO BUILDING HEIGHTS OVER THE DISTRICT.
 COOLING IN RESPONSE TO AN APPROACHING TROUGH OF LOW PRESSURE
 DEVELOPS MON WITH THE ECMWF STRONGER AND MORE PROGRESSIVE WITH
 THIS FEATURE THAN GFS. HAVE LEANED TOWARD A BLEND OF BOTH FOR
 GENERAL COOLING AND STRONGER MARINE INFLUENCE AND ENHANCED DELTA
 BREEZES. STILL GENERALLY DRY AND SEASONAL TEMPERATURES MOST AREA
 EXCEPT SLIGHT CHANCES SHOWERS IN THE FAR NORTH MON THROUGH WED.
 DK2
 
 
 &&
 
 .AVIATION...
 
 FOR THE NEXT 24 HOURS HIGH PRESSURE ALOFT WILL DOMINATE THE
 WEATHER PATTERN. A FEW LOW CLOUDS NEAR THE EASTERN SAN FRANCISCO
 BAY MAY SPREAD OVER THE WESTERN DELTA REGION EARLY WED BUT WILL
 DISSIPATE BY 16Z. DELTA BREEZE CONDITIONS WITH LOCAL SW GUSTS TO 30
 KTS ARE POSSIBLE MAINLY AFTER 20Z. ISOLATED THUNDERSTORMS MAY
 DEVELOP OVER THE MOUNTAINS OF NORTHERN CA LATE WED. DK2
 
 &&
 
 .STO WATCHES/WARNINGS/ADVISORIES...
 NONE.
 &&
 
 $$


  NWS STO Office Area Forecast Discussion
  

   
 FXUS66 KSTO 160326
 AFDSTO
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SACRAMENTO CA
 826 PM PDT TUE MAY 15 2012
 
 .SHORT TERM DISCUSSION...
 
 AN ISOLATED SHOWER MADE ITS WAY ALONG THE CREST IN ALPINE COUNTY
 THIS EVENING FROM THE ACTIVITY OVER NEVADA THAT ROLLED SOUTH THROUGH
 LAKE TAHOE. THAT ACTIVITY CONTINUES TO WEAKEN NOW THAT THE SUN HAS
 SET AND SHOULD BE TAPERING OFF OVER THE NEXT COUPLE OF HOURS NEAR
 THE CREST. MODERATE FLOW WILL CONTINUE THOUGH THE DELTA OVERNIGHT
 AND WILL COOL THE INTERIOR VALLEY DOWN INTO THE 50S.
 
 A FLAT RIDGE WILL BE OVER THE AREA FOR WEDNESDAY SO I DONT EXPECT
 A LOT OF CHANGE IN TEMPERATURES FROM TODAY OTHER THAN SOME SLIGHT
 WARMING AND MAINLY FOR AREAS AWAY FROM THE DELTA AND SACRAMENTO 
 AREA. CONDITIONS LOOK TO REMAIN DRY FOR MOST AREAS AS WELL BUT
 SOME WEAK FORCING OVER THE FAR NORTHERN PART OF THE STATE MAY
 GENERATE A FEW SHOWERS OR AN ISOLATED THUNDERSTORM. WE SHOULD
 CONTINUE TO GET A MODERATE INFLUENCE THROUGH THE DELTA DURING THIS
 TIME...AND IT SHOULD BE A LITTLE STRONGER THAN TODAY.
 
 WEDNESDAY NIGHT THE WINDS WILL BE STRONG AT TIMES THROUGH THE
 DELTA AS THE SYSTEM MOVES THROUGH THE REGION AND SHOULD CONTINUE
 TO BE AT LEAST MODERATE DURING THE DAY. EXPECT MORE COOLING TO
 OCCUR WITH HIGHS COOLING BACK INTO THE MID 70S TO LOWER 80S FOR
 THE VALLEY...WITH THE COOLEST TEMPERATURES IN THE DELTA AND AREAS
 NEAR THE DELTA. A 70 TO 80KT JET WILL MOVE OVER THE SOUTHERN
 SACRAMENTO VALLEY LATE WEDNESDAY NIGHT AND THURSDAY. THIS WILL
 BRING SOME SHOWER AND THUNDERSTORM CHANCES MAINLY NORTH OF I-80
 FOR THE MOUNTAINS WITH A SLIGHT CHANCE OF SOME ISOLATED ACTIVITY
 OVER THE NORTHERN HALF OF THE SACRAMENTO VALLEY.
 
 THE TROUGH WILL MOVE EAST OF THE AREA ON FRIDAY TO ALLOW
 TEMPERATURES TO WARM UP BACK INTO THE 80S AND THE INTERIOR LOOSES
 IT THREAT OF ANY SHOWER OR THUNDERSTORM ACTIVITY.
 
 
 .EXTENDED DISCUSSION (SATURDAY THROUGH TUESDAY)
 
 MEDIUM RANGE MODELS SUGGESTING INCREASING HEIGHTS OVER INTERIOR
 NORCAL THROUGH SUNDAY RESULTING IN WARMING AMS AND DRY WEATHER.
 HIGH TEMPERATURES OVER THE WEEKEND EXPECTED IN THE MID 80S FOR THE
 CENTRAL VALLEY WITH UPPER 60S TO UPPER 70S FOR MOST OF THE
 MOUNTAIN AND FOOTHILL LOCATIONS. MODELS CONTINUE TO DIFFER WITH
 SOLUTIONS FOR EARLY NEXT WEEK. GEM MOVES DEEPER TROUGHING THROUGH
 WHILE ECMWF-HIRES MAINTAINS STRONGER RIDGING. OPER GFS IS A
 COMPROMISE BETWEEN THE TWO AND FORECAST FOLLOWS THIS MODEL ATTM
 WHICH SUGGESTS A SLIGHT CHANCE OF SHOWERS OVER THE NORTHERN
 MOUNTAINS MONDAY INTO TUESDAY. REMAINDER OF INTERIOR NORCAL WILL
 EXPERIENCE SOME SYNOPTIC COOLING WITH INCREASED DELTA FLOW.
 
 
 &&
 
 .AVIATION...
 
 UPR RDG OVR INTR NORCAL NXT 24 HRS WITH VFR CONDS EXC ISOLD MVFR/IFR 
 CONDS POSS VCNTY DELTA IN ST BTWN 12Z-18Z. LCL SWLY SFC WND GSTS UP 
 TO 30 KTS POSS VCNTY DELTA TNGT INTO WED MRNG.
 
 
 &&
 
 .STO WATCHES/WARNINGS/ADVISORIES...NONE. 
 
 &&
 
 $$


  NWS STO Office Area Forecast Discussion
  

   
 FXUS66 KSTO 152203
 AFDSTO
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SACRAMENTO CA
 330 PM PDT TUE MAY 15 2012
 
 .SHORT TERM DISCUSSION...
 FAIR SKIES OVER THE CWA THIS AFTERNOON UNDER BUILDING UPPER RIDGE. 
 TEMPERATURES THIS AFTERNOON ARE RUNNING FROM 4 TO 8 DEGREES ABOVE 24 
 HOURS AGO IN WARMING AIRMASS. A WEAK SHORTWAVE TROUGH RIDING OVER 
 THE TOP OF THE RIDGE AND INTO THE PACIFIC NORTHWEST SEEMS TO BE 
 HAVING LITTLE IMPACT ON NORCAL WEATHER. AS THIS SHORTWAVE DROPS INTO 
 DEFORMATION ZONE OVER NORTHEAST CALIFORNIA THERE COULD BE JUST 
 ENOUGH INSTABILITY PRODUCED FOR AN ISOLATED THUNDERSTORM IN THIS 
 REGION SO LEFT IN SLIGHT EVENING THUNDERSTORM THREAT TODAY. AFTER 
 MIDNIGHT TONIGHT...FLOW ALOFT BECOMES WEST TO SOUTHWEST ALL AREAS 
 ENDING ANY RESIDUAL SHOWER THREAT.  
 
 WEST COAST UPPER RIDGE STARTS GETTING FLATTENED ON WEDNESDAY AS LATE 
 SEASON PACIFIC TROUGH NOW OUTSIDE 140 WEST PUSHES TOWARDS THE COAST. 
 AIRMASS COOLS A BIT WITH A SLIGHT INCREASE IN ONSHORE FLOW. 
 THEREFORE...SHOULD SEE LITTLE CHANGE OR A LITTLE COOLING MOST AREAS 
 WEDNESDAY AND HAVE TRIED TO REFLECT THIS IN AFTERNOON PACKAGE GRIDS 
 BASED ON TODAYS FORECAST HIGHS.  GFS PIVOTS A WEAK DISTURBANCE OUT 
 AHEAD OF THE TROUGH AND BRINGS A SLIGHT THREAT OF SHOWERS TO THE 
 NORTHERN MOUNTAINS WEDNESDAY AFTERNOON. OTHER MODELS DO NOT HAVE 
 THIS FEATURE AND MOISTURE IS LIMITED SO AGAIN...T-STORM THREAT IS 
 VERY LIMITED. 
 
 UPPER TROUGH AXIS FORECAST TO REACH THE COAST THURSDAY AFTERNOON. 
 MODERATE LIFT...INSTABILITY AND INCREASED MOISTURE MAKE 
 THUNDERSTORMS A PRETTY GOOD BET ACROSS THE NORTHERN CWA ALTHOUGH 
 CONDITIONS DO NOT LOOK QUITE AS UNSTABLE AS YESTERDAY. 
 ELSEWHERE...COOLER TEMPERATURES BY ABOUT 5 TO 10 DEGREES ARE IN 
 STORE FOR THURSDAY AS COOLER MARINE AIR PUSHES INLAND. UPPER RIDGE 
 STARTS TO BECOME REESTABLISHED FRIDAY FOR A WARMING AND DRYING 
 TREND GOING INTO THE WEEKEND. 
 
 &&
 
 .EXTENDED DISCUSSION (SATURDAY THROUGH TUESDAY)...
 MEDIUM RANGE MODELS SUGGESTING INCREASING HEIGHTS OVER INTERIOR 
 NORCAL THROUGH SUNDAY RESULTING IN WARMING AMS AND DRY WEATHER. HIGH 
 TEMPERATURES OVER THE WEEKEND EXPECTED IN THE MID 80S FOR THE 
 CENTRAL VALLEY WITH UPPER 60S TO UPPER 70S FOR MOST OF THE MOUNTAIN 
 AND FOOTHILL LOCATIONS. MODELS CONTINUE TO DIFFER WITH SOLUTIONS FOR 
 EARLY NEXT WEEK. GEM MOVES DEEPER TROUGHING THROUGH WHILE 
 ECMWF-HIRES MAINTAINS STRONGER RIDGING. OPER GFS IS A COMPROMISE 
 BETWEEN THE TWO AND FORECAST FOLLOWS THIS MODEL ATTM WHICH SUGGESTS 
 A SLIGHT CHANCE OF SHOWERS OVER THE NORTHERN MOUNTAINS MONDAY INTO 
 TUESDAY. REMAINDER OF INTERIOR NORCAL WILL EXPERIENCE SOME SYNOPTIC 
 COOLING WITH INCREASED DELTA FLOW.
 
 &&
 
 .AVIATION...
 UPR RDG OVR INTR NORCAL NXT 24 HRS WITH VFR CONDS EXC ISOLD MVFR/IFR 
 CONDS POSS VCNTY DELTA IN ST BTWN 12Z-18Z. LCL SWLY SFC WND GSTS UP 
 TO 30 KTS POSS VCNTY DELTA TNGT INTO WED MRNG.
 
 &&
 
 .STO WATCHES/WARNINGS/ADVISORIES...NONE.
 
 &&
 
 $$


  NWS STO Office Area Forecast Discussion
  

   
 FXUS66 KSTO 151651
 AFDSTO
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SACRAMENTO CA
 1000 AM PDT TUE MAY 15 2012
 
 .SHORT TERM DISCUSSION...
 WATER VAPOR IMAGERY SHOWS UPPER LOW WHICH MOVED THROUGH CENTRAL 
 CALIFORNIA ON MONDAY NOW CENTERED OVER WEST CENTRAL NEVADA. MORNING 
 SOUNDING DATA NOW SHOWING NORTHERLY FLOW OVER CWA. MAIN FORECAST 
 CONCERN NEXT FEW DAYS WILL BE THUNDERSTORM POTENTIAL OVER THE 
 NORTHERN MOUNTAINS AND POSSIBLY NORTHERN SACRAMENTO VALLEY ON 
 THURSDAY. FOR TODAY...WEAK EASTERLY FLOW AROUND NEVADA LOW MAY 
 GENERATE ENOUGH OROGRAPHICS OVER LASSEN AREA FOR ISOLATED 
 THUNDERSTORMS. MOISTURE IS LIMITED HOWEVER AND LIFT FROM WEAK 
 DISTURBANCE PASSING OVER THE RIDGE IS LIMITED TOO SO THREAT LOOKS 
 VERY SMALL AT THIS TIME. OTHERWISE FAIR DAY TODAY WITH AIRMASS 
 WARMING BRINGING ABOUT 10 DEGREES OF WARMING OVER YESTERDAY. UPPER 
 LOW STARTS GETTING FLATTENED ON WEDNESDAY AS LATE SEASON PACIFIC 
 TROUGH PUSHES TOWARDS THE COAST. AIRMASS COOLS A BIT WITH A SLIGHT 
 INCREASE IN ONSHORE FLOW. THEREFORE...SHOULD SEE A LITTLE COOLING 
 MOST AREAS WEDNESDAY. GFS PIVOTS A WEAK DISTURBANCE OUT AHEAD OF THE 
 TROUGH AND BRINGS A SLIGHT THREAT OF SHOWERS TO THE NORTHERN 
 MOUNTAINS WEDNESDAY AFTERNOON. OTHER MODELS DO NOT HAVE THIS FEATURE 
 AND MOISTURE IS LIMITED SO AGAIN...T-STORM THREAT IS VERY LIMITED. 
 
 UPPER TROUGH AXIS FORECAST TO REACH THE COAST THURSDAY AFTERNOON. 
 MODERATE LIFT...INSTABILITY AND INCREASED MOISTURE MAKE 
 THUNDERSTORMS A PRETTY GOOD BET ACROSS THE NORTHERN CWA ALTHOUGH 
 CONDITIONS DO NOT LOOK QUITE AS UNSTABLE AS YESTERDAY. 
 ELSEWHERE...COOLER TEMPERATURES BY ABOUT 10 DEGREES ARE IN STORE FOR 
 THURSDAY AS COOLER MARINE AIR PUSHES INLAND. UPPER RIDGE BECOMES 
 REESTABLISHED FRIDAY FOR A WARMING AND DRYING TREND GOING INTO THE 
 WEEKEND. 
 
 &&
 
 .EXTENDED DISCUSSION (SATURDAY THROUGH TUESDAY)...
 MEDIUM RANGE MODELS SUGGESTING INCREASING HEIGHTS OVER INTERIOR
 NORCAL THIS WEEKEND RESULTING IN SLIGHT WARMING AND DRY WEATHER.
 HIGH TEMPS IN THE CENTRAL VALLEY WARM THROUGH THE 80S OVER THE 
 WEEKEND. UPPER TROUGH PROGGED TO MOVE INTO NORCAL EARLY NEXT WEEK 
 BUT MODELS DIFFER ON TIMING WITH GEM AND GFS SLOWER IN PROGRESSING 
 SYSTEM TOWARDS THE CWA. MAIN IMPACT AT THIS TIME LOOKS TO BE SOME 
 SLIGHT SYNOPTIC COOLING WITH AN INCREASED DELTA BREEZE AND LIGHT 
 SHOWERS OVER NRN MTNS MON AND TUE. 
 
 &&
 
 .AVIATION...
 ENOUGH INSTABILITY TO TRIGGER ISOLD TSRA OVER NRN MTNS 
 THIS AFTN/EVENING...MAINLY LASSEN PARK REGION. MAINLY VFR CONDS OVER 
 INTR NORCAL NEXT 24 HRS EXC TOWARD BAY AREA IN MARINE STRATUS LAYER 
 LESS THAN 1000FT AGL. MAINLY LIGHT S TO SW WINDS LESS THAN 12 KNOTS. 
 
 &&
 
 .STO WATCHES/WARNINGS/ADVISORIES...NONE.
 
 &&
 
 $$


  NWS STO Office Area Forecast Discussion
  

   
 FXUS66 KSTO 151111
 AFDSTO
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SACRAMENTO CA
 411 AM PDT TUE MAY 15 2012
 
 .SHORT TERM DISCUSSION...
 THE CLOSED UPPER LOW IS OVER THE SIERRA NEVADA TO THE SOUTH OF
 LAKE TAHOE EARLY THIS MORNING AND WILL MOVE SLOWLY EASTWARD INTO
 CENTRAL NV TODAY. SKIES HAVE CLEARED ACROSS THE REGION IN ITS
 WAKE. TEMPERATURES WILL REBOUND TODAY AS GENERAL AIRMASS WARMING
 RETURNS AND ONSHORE FLOW WEAKENS.
 
 THE UPPER RIDGE OVER THE EPAC WILL MOVE INTO NORCAL BY THIS
 AFTERNOON AND SHOULD RESULT IN LESS CONVECTIVE ACTIVITY ACROSS THE
 NORTHERN MOUNTAINS ABSENT ANY TRIGGERING MECHANISM. HOWEVER...
 FORECAST SOUNDINGS OVER NORTHERN SHASTA COUNTY DO SHOW LINGERING
 MOISTURE AND STEEP LAPSE RATES THOUGH DOUBTFUL THAT SURFACE
 HEATING ALONE WILL BE SUFFICIENT TO LIFT PARCELS TO THE LFC.
 
 THE RIDGE WILL FLATTEN A BIT TONIGHT AND WEDNESDAY AHEAD OF
 ANOTHER LATE-SEASON TROUGH FROM THE GOA THAT IS FORECAST TO MOVE
 THROUGH THE REGION THURSDAY INTO EARLY FRIDAY. THIS WILL PROVIDE
 GREATER POTENTIAL FOR ISOLATED AFTERNOON/EVENING CONVECTION OVER
 THE NORTHERN MOUNTAINS ON WEDNESDAY. TEMPERATURES ARE FORECAST TO
 WARM A BIT FURTHER WEDNESDAY BEFORE LOWERING 5-10 DEGREES THURSDAY
 AS THE TROUGH AFFECTS THE REGION. THE NORTHERN THIRD OF THE
 FORECAST AREA MAY SEE SCATTERED SHOWERS AND THUNDERSTORMS
 THURSDAY AS THE TROUGH MOVES THROUGH...THEN TEMPERATURES MODERATE
 SLIGHTLY AND QUIETER WEATHER RETURNS FRIDAY AS THE TROUGH SHIFTS
 EAST.
 
 &&
 
 .EXTENDED DISCUSSION (SATURDAY THROUGH TUESDAY)...
 MEDIUM RANGE MODELS SUGGESTING INCREASING HEIGHTS OVER INTERIOR
 NORCAL THIS WEEKEND RESULTING IN SLIGHT WARMING AND DRY WEATHER.
 HIGH TEMPS IN THE CENTRAL VALLEY WARM THROUGH THE 80S OVER THE
 WEEKEND. UPPER TROUGH PROGGED TO MOVE INTO NORCAL EARLY NEXT WEEK
 BUT MODELS DIFFER ON TIMING WITH GEM AND GFS SLOWER IN PROGRESSING
 SYSTEM TOWARDS THE CWA. MAIN IMPACT AT THIS TIME LOOKS TO BE SOME
 SLIGHT SYNOPTIC COOLING WITH AN INCREASED DELTA BREEZE AND LIGHT
 SHOWERS OVER NRN MTNS MON AND TUE. JCLAPP
 
 &&
 
 .AVIATION...
 UPPER LOW OVERHEAD MOVES INTO GREAT BASIN TODAY. ENOUGH INSTABILITY
 TO TRIGGER ISOLD TSRA OVER NRN MTNS THIS AFTN/EVENING...MAINLY
 LASSEN PARK REGION. MAINLY VFR CONDS OVER INTR NORCAL NEXT 24 HRS
 EXC TOWARD BAY AREA. MARINE LAYER LESS THAN 1200FT AGL AT BODEGA
 BAY...ST BASE 010 MSL NOT LIKELY TO EXTEND PAST I-680 FROM BENECIA
 TO CORDELIA THIS MORN...11Z TO 18Z. JCLAPP
 
 &&
 
 .STO WATCHES/WARNINGS/ADVISORIES...NONE.
 
 &&
 
 $$


  NWS STO Office Area Forecast Discussion
  

   
 FXUS66 KSTO 150347
 AFDSTO
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SACRAMENTO CA
 847 PM PDT MON MAY 14 2012
 
 .SHORT TERM DISCUSSION...
 
 THE LOW PRESSURE AREA IS CENTERED OVER THE SOUTHERN SACRAMENTO
 VALLEY WITH MAINLY MID TO HIGH CLOUDS WRAPPING BACK AROUND THE
 NORTH SIDE OF THE LOW THIS EVENING. MOST OF THE ECHOS THAT THE
 RADAR IS PICKING UP ON ARE ALOFT SO VERY FEW SHOWERS AROUND THIS
 EVENING. THE LOW WILL CONTINUE TO MOVE EASTWARD OVERNIGHT AND AS
 IT DOES ANY REMAINING SHOWER ACTIVITY WILL DIE DOWN...BUT SOME
 HIGH CLOUDS WILL LIKELY MOVE OVER THE SOUTHERN SACRAMENTO AREA
 LATE TONIGHT. TEMPERATURES WILL BE AT LEAST SEVERAL DEGREES OR
 MORE WARMER THAN TODAY BUT AROUND NORMAL FOR THIS TIME OF YEAR FOR
 TUESDAY AND CONDITIONS WILL BE DRY FOR THE INTERIOR.
 
 A FLAT RIDGE WILL BE OVER THE AREA FOR WEDNESDAY SO I DONT EXPECT
 A LOT OF CHANGE IN TEMPERATURES FROM TUESDAY TO WEDNESDAY OTHER
 THAN SOME SLIGHT WARMING. CONDITIONS LOOK TO REMAIN DRY FOR MOST
 AREAS AS WELL BUT SOME WEAK FORCING OVER THE FAR NORTHERN PART OF
 THE STATE MAY GENERATE A FEW SHOWERS OR AN ISOLATED THUNDERSTORM.
 WE SHOULD CONTINUE TO GET A MODERATE INFLUENCE THROUGH THE DELTA
 DURING THIS TIME.
 
 THURSDAY AS THE SYSTEM MOVES THROUGH THE REGION LOOK FOR MORE
 COOLING TO OCCUR WITH HIGHS COOLING BACK INTO THE MID 70S TO LOWER
 80S FOR THE VALLEY. THERE WILL ALSO BE SOME SHOWER AND
 THUNDERSTORM CHANCES MAINLY NORTH OF I-80 FOR THE MOUNTAINS WITH A
 SLIGHT CHANCE OVER THE FAR NORTHERN END OF THE SACRAMENTO VALLEY.
 
 .EXTENDED DISCUSSION (FRIDAY THROUGH MONDAY)
 
 MEDIUM RANGE MODELS SUGGESTING INCREASING HEIGHTS OVER INTERIOR 
 NORCAL FRIDAY THROUGH SUNDAY RESULTING IN WARMING AMS AND DRY 
 WEATHER. HIGH TEMPERATURES IN THE CENTRAL VALLEY WARM THROUGH THE 
 80S OVER THE WEEKEND. UPPER TROUGH PROGGED TO MOVE INTO NORCAL
 EARLY NEXT WEEK BUT MODELS DIFFER ON TIMING WITH GEM AND ECMWF-
 HIRES SLOWER IN PROGRESSING SYSTEM TOWARDS THE CWA. MAIN IMPACT
 ATTM LOOKS TO BE SOME SYNOPTIC COOLING OVER THE AREA WITH
 INCREASED ONSHORE FLOW.
 
 
 &&
 
 .AVIATION...
 
 UPR LOW OVHD MOVS INTO GRT BASIN TUE MRNG. ISOLD -SHRA POSS OVR
 WRN PLUMAS...SHASTA..AND TEHAMA CNTYS THRU 08Z. MNLY VFR CONDS
 OVR INTR NORCAL NXT 24 HRS EXC LCL MVFR/IFR POSS VCNTY DELTA IN ST
 BTWN 10Z-18Z TUE.
 
 
 &&
 
 .STO WATCHES/WARNINGS/ADVISORIES...
 NONE.
 &&
 
 $$


  NWS STO Office Area Forecast Discussion