000
FXUS66 KSTO 240437
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
937 PM PDT WED MAY 23 2012

.SHORT TERM DISCUSSION...

WINDS DIMINISHING MOST AREAS THIS EVENING...BUT REMAINING BREEZY
OVER THE NORTHERN SACRAMENTO VALLEY AND NORTHERN SAN JOAQUIN
VALLEY. WENT AHEAD AND EXPIRED THE WIND ADVISORY AT 8 PM AS WINDS
WERE BELOW ADVISORY LEVELS OVER THE AREA. TEMPERATURES WERE IN THE
UPPER 60`S TO LOW 70`S OVER VALLEY LOCATIONS AND LOW 50`S TO UPPER
40`S OVER THE MOUNTAINS. THESE VALUES WERE 2-5 DEGS COOLER VERSUS
YESTERDAY AT THIS TIME. FORECASTED OVERNIGHT LOWS ARE IN THE LOW
50`S FOR VALLEY LOCATIONS WHICH SEEMS RIGHT ON TRACK WITH CURRENT
TRENDS. NO EVENING UPDATE WILL BE NEEDED TO CURRENT FORECAST.

UPPER LOW ALONG THE WESTERN BRITISH COLUMBIA COAST WILL DROP SOUTH
THROUGH CALIFORNIA FRI-SAT. MODELS ARE IN EXTREMELY GOOD AGREEMENT
WITH THIS TIMING AND TRACK. THIS SYSTEM WILL BRING COOLER TEMPS
AND SCATTERED SHOWERS AND THUNDERSTORMS WITH A FEW INCHES OF SNOW
AT HIGH ELEVATIONS.

PREVIOUS DISCUSSION...

NOT MUCH CHANGE IN THE FORECAST PACKAGE EXCEPT FOR ALTERING THE
WIND ADVISORY. RECENT MODEL GUIDANCE SUGGESTS THAT WINDS SHOULD
LESSEN EARLIER THAN PREVIOUSLY FORECAST SO HAVE SHORTENED THE WIND
ADVISORY TO HAVE IT EXPIRE AT 8 PM INSTEAD OF 11 PM TONIGHT.
CURRENT NORTHERLY GRADIENT FROM MFR-SAC HAS INCREASED TO ABOUT 6
MB. STRONGEST WINDS ARE IN THE NORTHERN SAN JOAQUIN VALLEY WITH
PERSISTENT GUSTS BETWEEN 20-25 MPH AROUND THE STOCKTON-MODESTO
REGION. STRONGEST GUST RECORDED TODAY SO FAR IN THE NORTHERN SAN
JOAQUIN VALLEY WAS EAST OF OAKDALE AT 37 MPH.

CENTER OF THE UPPER LEVEL LOW ALONG THE WESTERN CANADIAN COASTLINE
WILL BE TRACKING SOUTHWARD ON THURSDAY NUDGING INTO FAR NORCAL BY
THURS AFTN/EVENING. THIS WILL RESULT IN TEMPERATURES ACROSS OUR
CWA COOLING BY ABOUT 5-10 DEGREES AS A SLIGHT CHANCE TO CHANCE OF
SHOWERS COULD IMPACT THE NORTHERN TERRAIN OF THE COASTAL...SHASTA
COUNTY...AND SIERRA MOUNTAINS AND POSSIBLY PUSH INTO THE NORTHERN
SACRAMENTO VALLEY.

FRIDAY MARKS THE BRUNT OF THE STORM AS THE CENTER OF THE UPPER LOW
WILL CONTINUE TO MOVE SOUTHWARD AND BE DIRECTLY OVER OUR CWA.
DURING THE DAY FRIDAY...EXPECT CHANCE OF SHOWERS THROUGHOUT THE
VALLEY WITH LIKELY SHOWERS ALONG THE SIERRA. THE UNSEASONABLE COLD
POOL ALOFT WILL CAUSE SURFACE TEMPERATURES TO BE ABOUT 10-20
DEGREES BELOW NORMAL ACROSS OUR CWA. VALLEY HIGHS SHOULD RANGE IN
THE UPPER 60S TO LOW 70S. THE COLD POOL WILL DROP SNOW LEVELS TO
ABOUT 5000-6000 FEET RESULTING IN UP TO 4 INCHES OF SNOWFALL
ALONG THE HIGHER ELEVATIONS OF THE SIERRA...HOWEVER MOST
ACCUMULATIONS SHOULD BE LIGHT WITH UP TO 1-2 INCHES OF SNOW.
INSTABILITY FROM THE COLD POOL SHOULD ALSO TRIGGER A SLIGHT CHANCE
OF THUNDERSTORM ACTIVITY ALONG THE SIERRA AND IN PORTIONS OF THE
VALLEY. RESIDENTS SHOULD KEEP IN MIND THAT LOCALLY GUSTY WINDS AND
BRIEF PERIODS OF HEAVY SHOWERS WITH SMALL HAIL ARE POSSIBLE DURING
THUNDERSTORMS.

THE CENTER OF THE LOW SHOULD TRACK TO THE EAST OF OUR CWA ON
SATURDAY WHICH WILL ALLOW LINGERING SHOWERS ALONG THE SIERRA.
OTHERWISE...THE REST OF INTERIOR NORCAL SHOULD BEGIN A WARMING AND
DRYING TREND.   JBB

&&

.EXTENDED DISCUSSION (SUNDAY THROUGH WEDNESDAY)

WEAK RIDGES AND TROUGHS DEPICTED IN MEAN WESTERLY FLOW ALOFT OVER
INTERIOR NORCAL THROUGH THE EXTENDED WILL RESULT IN DRY WEATHER.
MINOR WARMING WITH NEAR NORMAL TEMPERATURES THROUGH MONDAY.
INCREASING HEIGHTS TUESDAY INTO WEDNESDAY WILL RAISE HIGH TEMPS INTO
THE UPPER 80S TO LOWER 90S FOR THE CENTRAL VALLEY BY MIDWEEK.


&&

.AVIATION...

VFR CONDS OVR INTR NORCAL NXT 24 HRS. LCL W-NWLY SFC WND GSTS AOA
25 KTS OMTNS TNGT AND THU AND IN CNTRL VLY BTWN 15Z- 04Z THU.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$