000
FXUS66 KSTO 132203
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
330 PM PDT MON OCT 13 2008
.DISCUSSION...NORTHERLY SURFACE PRESSURE GRADIENTS HAVE SLOWLY
WEAKENED TODAY AND WINDS ARE ALSO DECREASING SLOWLY. WINDS STILL
STRONG ENOUGH AND HUMIDITY LOW ENOUGH TO ALLOW RED FLAG WARNING FOR
SAC VALLEY AND FOOTHILLS TO CONTINUE INTO THIS EVENING BUT WINDS
SHOULD CONTINUE TO DECREASE THROUGH THE NIGHT. TEMPERATURES THIS
AFTERNOON RUNNING ANYWHERE FROM 4 TO 12 DEGREES WARMER THAN
YESTERDAY SO HIGHS TODAY SHOULD COME IN NEAR OR JUST BELOW NORMAL
FOR THIS TIME OF YEAR. UPPER LEVEL WIND SUPPORT WILL WEAKEN BY
TUESDAY MORNING AS UPPER RIDGE CONTINUES TO SHIFT INLAND TUESDAY
WITH SURFACE GRADIENT EXPECTED TO WEAKEN AS WELL. A MORE EASTERLY
SURFACE GRADIENT TONIGHT WILL BRING AREAS OF GUSTY WINDS IN WEST
FACING CANYONS OF THE SIERRA AND FOOTHILLS BUT THESE STRONGER WINDS
WILL GENERALLY BE CONFINED TO THE MOST WIND PRONE AREAS.
BY TUESDAY AFTERNOON PRESSURE GRADIENTS AT ALL LEVELS BECOME MUCH
LIGHTER SO WINDS SHOULD REMAIN GENERALLY LIGHT THROUGH THE MIDDLE OF
THE WEEK. ALTHOUGH HIGH PRESSURE IS FORECAST TO REMAIN OVER THE
STATE...SHORTWAVES RIDING OVER THE RIDGE AND THROUGH THE PACIFIC
NORTHWEST WILL KEEP THE RIDGE SUPPRESSED SOMEWHAT SO DAYTIME HIGH
TEMPERATURES SHOULD REMAIN FAIRLY CONSTANT THROUGH WEDNESDAY.
.EXTENDED FORECAST (THURSDAY THROUGH MONDAY)...UPPER LEVEL RIDGING
REBUILDS ON THURSDAY BRINGING SLIGHTLY ABOVE AVERAGE TEMPERATURES
WITH SUNNY SKIES. AN APPROACHING TROUGH WILL BEGIN TO FLATTEN THE
RIDGE ON FRIDAY WITH SLIGHTLY COOLER TEMPERATURES. 12Z ECMWF IS
TRENDING MORE TOWARDS THE COOLER GFS FOR THE WEEKEND AND INTO EARLY
NEXT WEEK...WITH PREVIOUS RUNS SHOWING MORE OF A PERSISTENT WEAK
RIDGING PATTERN. MODELS SUGGEST A COLD FRONT WILL PUSH THROUGH LATE
FRIDAY INTO SATURDAY WITH INCREASING CLOUDS AND BELOW AVERAGE
TEMPERATURES INTO EARLY NEXT WEEK. SHORTWAVE ENERGY AND MOISTURE IS
EXPECTED TO REMAIN TO THE NORTH. GFS HAS RIDGING GIVING WAY TO A
PACIFIC TROUGH ON MONDAY...WHILE ECMWF IS SLOWER BRINGING THE SYSTEM
IN LATER IN THE AFTERNOON AND EVENING. THIS WILL BRING THE POTENTIAL
FOR PRECIPITATION OVER NORTHERN PORTIONS OF THE FORECAST AREA AND A
COOLING TREND.
&&
.AVIATION...VFR CONDITIONS WITH CLEAR SKIES WILL CONTINUE OVERNIGHT.
NORTH WINDS IN THE SACRAMENTO VALLEY WILL DECREASE BY 00Z AND BECOME
GENERALLY LIGHT OVERNIGHT. LOCAL EAST GUSTS TO 30 KT POSSIBLE OVER
THE SIERRA CREST AND IN NORTHEAST ORIENTED CANYONS TUESDAY MORNING.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING THROUGH 7 PM PDT FOR THE SAC VALLEY AND DELTA ALONG
WITH THE COASTAL RANGE AND NORTHEASTERN FOOTHILLS BELOW 1500 FEET
FOR GUSTY NORTH WINDS AND LOW HUMIDITY.
&&
$$
