Small Craft Advisory 257, NWS San Francisco Bay Area, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
830 PM PDT SUN MAY 22 2011

.DISCUSSION...AS OF 8:30 PM PDT SUNDAY...WITH A MIXTURE OF HIGH AND
LOW CLOUDS OVER MUCH OF THE DISTRICT TODAY...TEMPERATURES TURNED
OUT TO BE COOLER THAN YESTERDAY BY SEVERAL DEGREES. HIGHS TODAY
RANGED FROM THE 50S AT THE OCEAN TO THE 60S AND 70S INLAND. SURFACE
PRESSURE GRADIENTS HAVE TIGHTENED WITH 4.5 MB CURRENTLY FROM SFO TO
SAC...4.9 MB FROM ACV TO SFO...AND 14.3 MB BETWEEN SFO AND LAS. AS A
RESULT...AFTERNOON SEABREEZE WINDS HAVE RAMPED UP AND THERE WAS EVEN
A WIND GUST TO 47 KNOTS AT SFO EARLIER THIS EVENING.

AN UPPER LEVEL LOW CURRENTLY OFF THE PACNW COAST WILL DROP SE
INTO THE GREAT BASIN LATE TONIGHT THROUGH MONDAY NIGHT. IN ITS
WAKE...WEAK RIDGING WILL DEVELOP OVER THE WEST COAST. A SLIGHT
WARMING TREND IS THUS EXPECTED THROUGH TUESDAY. BY WEDNESDAY...THE
RIDGE IS PROGGED TO WEAKEN AS A LATE-SEASON STORM SYSTEM APPROACHES
FROM THE GULF OF ALASKA. THIS IS EXPECTED TO BRING SOME RAIN TO
MAINLY THE NORTHERN HALF OF THE DISTRICT WEDNESDAY AND WEDNESDAY
NIGHT. IN ADDITION TO RAIN CHANCES...THIS SYSTEM WILL ALSO BRING IN
COOLER TEMPERATURES...AT LEAST ACROSS NORTHERN SECTIONS. SOUTHERLY
FLOW AND DRY CONDITIONS COULD LEAD TO SLIGHTLY WARMER TEMPS ACROSS
THE EXTREME SOUTHERN PART OF THE CWA.

ZONAL FLOW ALOFT AND WEAK SHORT-WAVE TROUGH PASSAGES COULD LEAD TO
SOME UNSETTLED WEATHER DURING PARTS OF THE EXTENDED FORECAST PERIOD
WITH COOL TEMPERATURES INTO THE HOLIDAY WEEKEND.

&&

.AVIATION...AS OF 5:00 PM PDT SUNDAY...STRONG E-W PRESSURE GRADIENTS
RESULTING IN STRONG WINDS NEAR SFO. THIS WILL KEEP VFR CONDITIONS
FOR THE SFO BAY AREA THROUGH THE AIRPORT EVENING RUSH HOUR. LOW
CLOUDS WILL SLOWLY INCREASE LATER TONIGHT.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH THE AIRPORT
EVENING RUSH HOUR WITH MVFR CIGS SLOWLY INCREASING AFTER 05Z.
STRONG WEST WINDS 30-40 KT WITH LOCALLY HIGHER GUSTS THROUGH 03Z.
WINDS DECREASING TO 20-30 KT AFTER 03Z CONTINUING THROUGH THE
REST OF THE NIGHT.

KSFO BRIDGE APPROACH...VFR CONDITIONS EXPECTED THROUGH THE AIRPORT
EVENING RUSH HOUR WITH MVFR CIGS SLOWLY INCREASING AFTER 05Z.

MONTEREY BAY AREA TERMINALS...MVFR CIGS COULD BRIEFLY CLEAR
BETWEEN NOW AND 04Z. CIGS RETURNING AFTER 04Z.

&&

.MTR WATCHES/WARNINGS...
     .TNGT...SCA...ALL COASTAL WATERS.
            .SCA...ROUGH BAR...SAN FRANCISCO BAR.
            .SCA...MONTEREY BAY UNTIL 9 PM.

&&

PUBLIC FORECAST: SIMS
AVIATION/MARINE: CW/W PI