Small Craft Advisory 171, NWS San Francisco Bay Area, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
229 PM PST WED DEC 16 2015

.SYNOPSIS....ALTHOUGH WARMER IN MOST LOCATIONS BE PREPARED FOR
ANOTHER ROUND OF COLD TEMPERATURES TONIGHT. A FREEZE WARNING WILL
BE IN EFFECT LATE TONIGHT INTO THURSDAY MORNING FOR SOUTHERN
MONTEREY AND SAN BENITO COUNTIES. THERE IS A CHANCE OF LIGHT RAIN
IN THE NORTH BAY THURSDAY INTO FRIDAY. WIDESPREAD RAINFALL IS THEN
EXPECTED TO SPREAD ACROSS THE ENTIRE REGION LATE FRIDAY INTO
SATURDAY AS A FRONTAL BOUNDARY PUSHES THROUGH. UNSETTLED WEATHER
IS ANTICIPATED INTO NEXT WEEK.

&&

.DISCUSSION...AS OF 2:30 PM PST WEDNESDAY...MOSTLY SUNNY SKIES
AROUND THE AREA THIS AFTERNOON WITH TEMPERATURES CURRENTLY IN THE
MID 50S AT MOST LOCATIONS. COLD AIR REMAINS IN PLACE IN THE IN LAND
VALLEYS WHERE CURRENT TEMPERATURES REMAIN IN THE MID TO UPPER 40S.
SOME HIGH CLOUDS ARE ANTICIPATED TO WORK THEIR WAY INTO THE AREA
TONIGHT...MAINLY SAN JOSE AND NORTH. THESE HIGH CLOUDS WILL
INHIBIT THE RADIATIVE COOLING PROCESS PROMOTING SLIGHTLY WARMER
LOW TEMPERATURES OVERNIGHT TONIGHT COMPARED TO LAST NIGHT.
HOWEVER...DEW POINTS FROM AROUND THE LOCAL AREA ARE RANGING
BETWEEN -1 C TO ABOUT 2 C...SO TONIGHT WILL BE A CHILLY ONE. IN FACT
AREAS WHERE LITTLE TO NO HIGH CLOUDS ARE TONIGHT WILL SEE FREEZING
TEMPERATURES ONCE AGAIN. THEREFORE...HAVE ISSUED A FREEZE WARNING
FOR SOUTHERN MONTEREY AND SAN BENITO COUNTIES.

NOT MUCH HAS CHANGED OVER THE PAST 8 HOURS WITH THE SYNOPTIC SCALE
WEATHER PATTERN. THE CURRENT SATELLITE WATER VAPOUR IMAGE
CONTINUES TO SHOW A RIDGE OF HIGH PRESSURE OVER THE EASTERN
PACIFIC WITH MOISTURE PUSHING INTO THE PACIFIC NORTHWEST. THE LOW
PRESSURE SYSTEM CENTERED OVER MINNESOTA THIS MORNING HAS PUSHED
NORTHEAST TOWARDS CANADA. THE 1200Z ECMWF AND 1800Z GFS40 HAVE
INITIALIZED WELL WITH THESE SYNOPTIC SCALE WEATHER FEATURES AND
REMAIN IN GOOD AGREEMENT THROUGH ROUGHLY THE MIDDLE OF NEXT
WEEK.

BOTH MODELS CONTINUE TO SLIDE A WARM FRONT ACROSS NORTHERN
CALIFORNIA THURSDAY MORNING WHICH MAY BRING SOME LIGHT RAIN INTO
SONOMA COUNTY. A COLD FRONT WILL THEN SLIDE THROUGH THE ENTIRE CWA
FRIDAY WITH THE PARENT LOW PASSING OVER ON SATURDAY. ONCE THIS LOW
PRESSURE SYSTEM DEPARTS THE AREA A RIDGE OF HIGH PRESSURE BUILDS
OVER THE EASTERN PACIFIC PLACING OUR CWA UNDER MOIST NORTHWESTERLY
FLOW THROUGH AT LEAST TUESDAY. AT THIS POINT IT DOESN'T LOOK LIKE
ANY MAJOR IMPACTS WILL ACCOMPANY THIS UNSETTLED WEATHER PATTERN.

&&

.AVIATION...AS OF 10:00 AM PST WEDNESDAY... PREDOMINATELY VFR WITH
LIGHT WINDS. LOWERING CIGS AT THE END OF THE FORECAST PERIOD BUT
WILL REMAIN VFR.

VICINITY OF KSFO...VFR. HIGH CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR. HIGH CONFIDENCE.

&&

.MARINE...AS OF 09:59 AM PST WEDNESDAY...A LONG PERIOD NORTHWEST
SWELL HAS ENTERED THE COASTAL TODAY PRODUCING ENERGETIC SURF NEAR
HARBOR ENTRANCES...JETTIES AND THE SAN FRANCISCO BAR. MODERATE
SEAS WILL CONTINUE THROUGH THE END OF THE WORK WEEK WITH WEAKENING
WINDS. UNSETTLED WEATHER RETURNS OVER THE WEEKEND WITH INCREASING
WINDS AND SEAS.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
 .TNGT...FREEZE WARNING...FREEZE WARNING LATE TONIGHT FOR SOUTHERN
                          MONTEREY AND SAN BENITO COUNTIES CAZ516>518

&&

PUBLIC FORECAST: LARRY
AVIATION: DRP
MARINE: DRP

VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK AND TWITTER AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA