Small Craft Advisory 26, NWS San Francisco Bay Area, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
857 PM PDT SUN MAR 17 2013

...LIGHT RAIN EXPECTED TO MOVE INTO THE FORECAST AREA TUESDAY...

.DISCUSSION...AS OF 8:56 PM PDT SUNDAY...CURRENT OBSERVATIONS FROM
AROUND THE AREA ARE INDICATING MOSTLY CLEAR SKIES THIS EVENING
WITH THE EXCEPTION OF HALFMOON BAY WHICH IS REPORTING BKN CIGS.
THE FINAL LOW LIGHT VIS IMAGE WAS SHOWING UPPER LEVEL CLOUDS
FILTERING INTO THE AREA AHEAD OF THE APPROACHING STORM SYSTEM.
WITH THE ADDITION OF CLOUD COVER AND WARM AFTERNOON TEMPERATURES
OVERNIGHT LOW TEMPERATURES WILL BE RELATIVELY MILD. LOWS ARE
EXPECTED TO ONLY FALL INTO THE LOW TO MID 40S AT MOST LOCATIONS.

INCREASING MID TO UPPER LEVEL CLOUDS ARE EXPECTED TOMORROW AS THE
LOW CURRENTLY POSITIONED AT 150W 36N APPROACHES THE WEST COAST.
THE UPPER LEVEL RIDGE CURRENTLY POSITIONED OVER THE EASTERN
PACIFIC WILL BEGIN TO FLATTEN TOMORROW BECOMING ZONAL BY TUESDAY.
MOIST ZONAL FLOW WILL THEN PUSH INTO THE CWA RESULTING IN LIGHT
RAIN ACROSS THE FORECAST AREA FOR TUESDAY AND WEDNESDAY. ISENTROPIC
ANALYSIS DOES INDICATE THAT PRECIPITABLE WATER ALONG THE COAST
WILL INCREASE TO JUST OVER AN INCH...1.0 TO 1.17 INCHES...TUESDAY
NIGHT INTO WEDNESDAY MORNING. MODEST ISENTROPIC ASCENT AND LIGHT WEST
WINDS ALIGNED NORMAL TO THE COASTAL MOUNTAINS WILL PROMOTE
OROGRAPHIC ENHANCEMENT TUESDAY NIGHT INTO WEDNESDAY MORNING. THE
GREATEST QPF WILL BE SEEN ALONG THE COASTAL MOUNTAINS AND AT THIS
POINT THE FORECAST IS LESS THAN AN INCH AT MOST LOCATIONS. THIS
MAYBE A LITTLE UNDER DONE WHEN CONSIDERING OROGRAPHIC ASCENT UNDER
ZONAL FLOW. WILL WAIT TO ADJUST THE QPF FORECAST UNTIL THE NEXT
MODEL RUNS BECOME AVAILABLE.

BOTH THE 1800Z GFS AND 1200Z ECMWF QUICKLY BUILD HIGH PRESSURE
OVER THE FORECAST AREA THURSDAY AS THE STORM SYSTEM DEPARTS. THIS
HIGH PRESSURE WILL BRING A RETURN OF DRY WEATHER AND A SIGNIFICANT
WARM UP FOR THE END OF THE WORK WEEK INTO THE WEEKEND.

&&

.AVIATION...AS OF 5:45 PM PDT SUNDAY...HIGH CLOUDS WILL CONTINUE
TO STREAM IN OVERNIGHT WITH LIGHT TO MODERATE WEST WINDS. VFR
CONDITIONS EXPECTED ACROSS MOST TERMINALS THROUGH THE FORECAST
PERIOD WITH THE EXCEPTION OF KMRY FOR EARLY MORNING IFR CIGS.

VICINITY OF KSFO...VFR CONDITIONS WITH MAINLY HIGH CLOUDS ACROSS
AREA TERMINALS. WEST WINDS SUSTAINED AROUND 20 KT WITH GUSTS TO
25 KT EXPECTED UNTIL 04Z. WINDS WILL GRADUALLY EASE OVERNIGHT
DROPPING BELOW 10 KT AFTER 06Z.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WITH MAINLY HIGH
CLOUDS ACROSS AREA TERMINALS EXPECTED THROUGH THIS EVENING.
POSSIBLE IFR CIGS OVER KMRY BETWEEN 12Z AND 16Z MONDAY MORNING.
WEST WINDS WILL EASE OVERNIGHT BECOMING LIGHT AND VARIABLE.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 2 AM
             SCA...PT ARENA TO PIGEON PT 10-60 NM
             SCA...PIGEON PT TO PT PIEDRAS BLANCAS 10-60 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
             SCA...PT ARENA TO PT REYES 0-10 NM UNTIL 3 AM
             SCA...PT REYES TO PIGEON PT 0-10 NM UNTIL 3 AM
             SCA...MRY BAY UNTIL 9 PM

&&

PUBLIC FORECAST: LARRY
AVIATION/MARINE: CW

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