Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA

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000
FXUS66 KMTR 251138
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
438 AM PDT FRI JUL 25 2014

.SYNOPSIS...WARM TO HOT WEATHER TODAY FOR MOST OF THE BAY AREA AS
HIGH PRESSURE BUILDS AND A THERMAL TROUGH PERSISTS NEAR THE COAST.
SOME SUBTLE COOLING IS POSSIBLE ON SATURDAY...MAINLY NEAR THE
COAST AS A STRONGER SEABREEZE DEVELOPS BUT WARM TO HOT WEATHER
WILL CONTINUE INLAND. NO BIG CHANGES THROUGH EARLY NEXT WEEK AS
HIGH PRESSURE CONTINUES WITH DRY WEATHER OVER THE BAY AREA AND
CONTINUED SEASONABLY WARM TEMPERATURES AWAY FROM THE COAST.

&&

.DISCUSSION...AS OF 3:15 AM PDT FRIDAY...MAIN WEATHER STORY FOR
TODAY WILL BE WARM TO HOT INLAND TEMPERATURES. THE NORTHERLY
GRADIENT IS STILL 5 MB DOWN THE COAST WITH SFO-WMC 3 MB OFFSHORE.
THE COAST IS CLEAR OF CLOUDS FOR THE MOST PART EXCEPT SOME SHALLOW
FOG RIGHT ALONG THE COAST. FOR EXAMPLE HALF MOON BAY AND MONTEREY
ARE BOTH REPORTING 400 FOOT CLOUD DECKS THAT ARE FORECAST TO MIX
OUT QUICKLY AFTER SUNRISE. IN GENERAL EXPECT TEMPERATURES TO WARM
AS MUCH AS 4 TO 8 DEGREES ABOVE YESTERDAYS READINGS. ALREADY AT
THIS HOUR MANY OF THE SITES UP IN THE HILLS ARE RUNNING AS MUCH AS
10 TO 20 DEGREES WARMER THAN LAST NIGHT AT THIS TIME. THIS IS
OCCURRING AS THE MARINE LAYER HAS COMPRESSED TO UNDER 1000 FEET
WITH CONTINUED AIRMASS WARMING AND SOME ADIABATIC COMPRESSION AS
THE THERMAL TROUGH HAS SHIFTED CLOSER TO THE COAST. IN GENERAL NOT
EXPECTING RECORD HIGHS TODAY BUT A FEW SITES COULD GET CLOSE.
RECORD HIGHS FOR LATE JULY NEAR THE COAST ARE ACTUALLY QUITE LOW
AS WERE OFTEN MIRED UNDER A PERSISTENT MARINE LAYER AND STRONG
ONSHORE WINDS. HOWEVER SINCE THE OFFSHORE FLOW IS ONLY WEAK AND A
SEABREEZE IS EXPECTED BELIEVE WE`LL FALL SHORT OF RECORDS AT
PLACES LIKE SF CITY...MONTEREY AND SALINAS. MEANWHILE INLAND AREAS
WILL BE HOT WITH 100 DEGREE HEAT FORECAST FOR THE EAST BAY
VALLEYS...SANTA CLARA VALLEY AND INTERIOR VALLEYS OF MONTEREY/SAN BENITO.

ALL MOS DATA SHOWS TODAY AS THE PEAK OF THE HEAT WITH A FEW
DEGREES OF COOLING FOR SATURDAY. HOWEVER FOR THE MOST PART THAT
MAY BE SPLITTING HAIRS AS ANOTHER HOT DAY IS IN STORE FOR SATURDAY
AWAY FROM THE COAST. LOOKING OVER THE MODEL DATA NOT SEEING ANY
SIGNS OF A SOUTHERLY WIND REVERSAL OR ANYTHING THAT WOULD BRING
DRAMATIC COOLING ON SATURDAY. HOWEVER THERE IS A SUBTLE RIPPLE IN
THE FLOW THAT SHOWS UP IN THE 500 MB FIELDS OFF THE COAST BY
SATURDAY AFTERNOON. THIS MAY BE JUST ENOUGH TO ENHANCE THE STRATUS
FIELD OVER THE OCEAN. IN ADDITION THE FORECAST ONSHORE GRADIENTS
FROM SFO-SAC ARE EXPECTED TO INCREASE BY SATURDAY AND USHER IN A
STRONGER SEABREEZE.

DAY TO DAY CHANGES SUNDAY THROUGH THURSDAY ARE HARD TO PIN DOWN AT
THIS TIME. FOR THE MOST PART EXPECT TEMPERATURES TO RUN NEAR NORMAL.
WE WILL HAVE TO MONITOR MONSOON POTENTIAL BUT FOR NOW THE MODELS
KEEP ANY MOISTURE OVER THE SIERRA AND NORTHERN MOUNTAINS OF THE
STATE.

&&

.AVIATION...AS OF 04:30 AM PDT FRIDAY...NORTHERLY GRADIENT
CONTINUES TO BE MODERATE AT OVER 5 MB SFO TO ACV. SHALLOW STRATUS
HAS FORMED ALONG THE COAST AFFECTING THE MRY BAY TERMINALS THIS
MORNING. THE CLOUDS SHOULD BURN OFF FAIRLY EARLY GIVEN HOW THIN
THEY ARE THOUGH THE NORTHWESTERLY COMPONENT OF THE WIND MAY HELP
PUSH MORE CLOUDS IN TO EITHER OF THE TERMINALS. OTHERWISE VFR
TODAY.

VICINITY OF KSFO...VFR. LIGHT NE WINDS POSSIBLE LATE
MORNING...TURNING WEST IN THE AFTERNOON.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR THIS MORNING. SHOULD BURN OFF BY
MID MORNING HOWEVER NORTHWESTERLY FLOW COULD LEAD TO LATER
CLEARING...MEDIUM TO LOW CONFIDENCE ON CLEARING TIME.

&&

.MARINE...AS OF 3:15 AM PDT FRIDAY...WINDS OVER THE COASTAL WATERS
WILL DECREASE TODAY AS THE SURFACE PRESSURE GRADIENT WEAKENS.
LIGHT WINDS AND SEAS WILL CONTINUE THROUGH THE WEEKEND EXCEPT
MODERATE NORTHWEST OVER THE NORTHERN OUTER WATERS.

&&

.CLIMATE...RECORD HIGH TEMPERATURES FOR FRIDAY JULY 25TH ALONG
WITH THE MOST RECENT DATE IT OCCURRED. * SIGNIFIES THERE ARE
ADDITIONAL YEARS THE RECORD WAS SET.

SF BAY AREA
.LOCATION................TEMP/YEAR
 KENTFIELD...............103/1975
 SAN RAFAEL.............. 98/1975
 NAPA....................101/1975
 SAN FRANCISCO........... 82/1973
 SFO AIRPORT............. 91/1973
 OAKLAND (DOWNTOWN)...... 97/1973
 OAKLAND AIRPORT......... 92/1973
 LIVERMORE...............111/1980
 MOFFETT FIELD........... 90/2006
 SAN JOSE................ 99/1975
 GILROY..................109/2006

MONTEREY BAY AREA
.LOCATION................TEMP/YEAR
 MONTEREY................ 83/2006
 SANTA CRUZ.............. 97/1973
 SALINAS................. 85/1975
 SALINAS AIRPORT......... 87/1973
 KING CITY...............104/1973

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...PT ARENA TO PT REYES 10-60 NM
             SCA...PT ARENA TO PT REYES 0-10 NM
             SCA...PT REYES TO PIGEON PT 10-60 NM

&&

$$

PUBLIC FORECAST: RWW
AVIATION/MARINE: AC

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