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

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000
FXUS66 KMTR 281221
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
521 AM PDT THU MAY 28 2015

.SYNOPSIS...HIGH PRESSURE BUILDING ALONG THE WEST COAST WILL
RESULT IN A MODEST WARMING TREND THROUGH SATURDAY...MOST APPARENT
INLAND. TEMPERATURES WILL THEN COOL SUNDAY INTO EARLY NEXT WEEK
AS A WEAK UPPER LEVEL TROUGH APPROACHES THE COAST. THERE IS A SLIGHT
CHANCE OF SHOWERS ACROSS THE NORTH BAY FROM LATE SUNDAY INTO
MONDAY...BUT MOST LOCATIONS ARE EXPECTED TO REMAIN DRY THROUGH THE
FORECAST PERIOD.

&&

.DISCUSSION...AS OF 3:53 AM PDT THURSDAY...MARINE LAYER STILL
AROUND 2000 FEET EARLY THIS MORNING WITH LOW CLOUDS SPREADING WELL
INLAND ONCE AGAIN. COMPARING SATELLITE IMAGERY FROM 24 HOURS AGO
REVEALS SIMILAR COVERAGE PATTERN...ALTHOUGH A LITTLE LESS SO FAR
THIS MORNING INTO THE DELTA AND UP NEAR PACHECO PASS. ANYWAY AS IT
STANDS RIGHT NOW THE INCOMING RIDGE IS LOOKING A LITTLE LESS
ROBUST AND NOT COMPRESSING THE MARINE LAYER AS MUCH AS PREVIOUSLY
EXPECTED. IN ADDITION ONSHORE GRADIENTS STILL REMAIN STRONG AT 2.5
SFO-SAC WITH HOWLING WINDS FROM THE GOLDEN GATE TO TRAVIS. NONE OF
THIS POINTS TO SIGNIFICANT WARMING TODAY...EVEN FOR INLAND AREAS.
MOS GUIDANCE FOR PLACES LIKE SANTA ROSA/CONCORD AND LIVERMORE ALL
REMAINS BELOW 80 DEGREES. ANYWAY...IT SHOULD WARM A FEW DEGREES
AGAIN TODAY AWAY FROM THE COAST BUT NOTHING TOO EXTREME. SCANNING
THE HILLS FOR HINTS OF WARMING AND MT TAM IS NOW 62 VERSUS 56 LAST
NIGHT BUT OFTEN TIMES WE`D LIKE TO SEE SOME OF THE RIDGES IN THE
HILLS CLOSER TO 70 TO BRING DOWN SOME TOASTY AFTERNOON AIR.

UPPER RIDGE WILL CONTINUE TO BUILD FRI AND SAT AND THE FORECAST
THEME WILL CONTINUE TO FOCUS ON WARMER TEMPERATURES INLAND BUT
REALLY NOTHING OUT OF THE ORDINARY WITH SOME 80S AND ONLY TOUCHING
90 FOR PLACES LIKE PINNACLES NATIONAL PARK. MEANWHILE CONTINUED
ONSHORE GRADIENTS WILL KEEP THE COAST COOL AND NOT EXPECTING
CLOUDS TO CLEAR FROM THE BEACHES MOST OF THE NEXT 3 DAYS AS ANY
BUILDING OF THE RIDGE WILL JUST COMPRESS THE MARINE LAYER AND
INDUCE SOME COASTAL DRIZZLE/FOG.

BY SATURDAY AFTERNOON A STRONGER SEABREEZE SHOULD BE NOTED AS A
TROUGH APPROACHES FROM THE WEST. THIS SYSTEM WILL BE OFF THE
MENDOCINO COAST BY SUNDAY AFTERNOON AND ECMWF/GFS TRENDS SUGGEST
SOME VERY LIGHT SHOWERS POSSIBLE FROM POINT REYES NORTHWARD ON
SUNDAY...SO THIS SYSTEM WILL BECOME THE FORECAST FOCUS IN THE MID
RANGE. NO REAL PRECIP CHANCES SOUTH OF THE GOLDEN GATE BUT COOLING
WILL OCCUR FOR ALL LOCATIONS ON SUNDAY AS THE MARINE LAYER DEEPENS
AND ONSHORE FLOW INCREASES ONCE AGAIN.

THE 00Z ECMWF KEEPS THE PATTERN ZONAL OR CYCLONIC BEHIND THAT
FRONT SUGGESTING NEAR TO BELOW NORMAL TEMPERATURES WILL CONTINUE
FOR THE START OF JUNE.

LOOKING FARTHER AHEAD IT WILL BE INTERESTING TO SEE IF WE GET ANY
TYPE OF PATTERN SHIFT AS WE HEAD DEEPER INTO JUNE. COASTAL BUOYS
STILL SHOW SST AROUND 51 DEGREES...SINCE THEY DROPPED IN EARLY
APRIL OUR PATTERN HAS BEEN NOTABLY COOLER.

&&

.AVIATION...AS OF 5:15 PM ADT THURSDAY... HIGH PRESSURE ALOFT
LEADING TO SUBSIDENCE OVER MARINE LAYER COMPRESSING MOISTURE TOWARDS
SURFACE. THIS IS RESULTING IN WIDESPREAD IFR CIGS WITH BASES
300-1000 FT THROUGH MOST OF THE FORECAST AREA THIS MORNING. RUC/WRF
GUIDANCE PUSHING FOR SIMILAR TIMING TO YESTERDAY... WITH GRADUALLY
LIFTING CIGS THROUGH THE MORNING AND MIX OUT BETWEEN 17-19Z FOR
MOST LOCATIONS. EARLY RETURN OF MVFR/IFR CIGS AT 01-03Z FOR MOST
LOCATIONS. ONSHORE FLOW 10- 16KT WITH GUSTS UP TO 24 KT THROUGH
THIS AFTERNOON WITH STRONGEST WINDS NEARSHORE.

VICINITY OF KSFO... IFR/MVFR THROUGH 18-19Z. BREEZY ONSHORE WINDS
THIS AFTERNOON. MVFR CIGS RETURN 01-02Z FRI.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS... IFR/MVFR THROUGH 18-19Z. ONSHORE
WINDS THIS AFTERNOON. MVFR CIGS RETURN 01-02Z FRI.

&&

.MARINE...AS OF 05:00 AM PDT THURSDAY...HIGH PRESSURE OVER THE
CALIFORNIA COASTAL WATERS TODAY WILL LEAD TO LIGHT TO LOCALLY
MODERATE NORTHWEST WINDS. THE STRONGEST WINDS WILL BE THROUGH THE
NORTH SAN FRANCISCO BAY... OFF OF THE SONOMA COASTLINE... AND
ALONG THE BIG SUR COASTLINE WITH BORDERLINE SMALL CRAFT CRITERIA
WINDS POSSIBLE. PREDOMINATELY GENTLE SEAS THROUGH THE PERIOD.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...SF BAY NORTH OF THE BAY BRIDGE FROM 2 PM
             SCA...PIGEON PT TO PT PINOS 0-10 NM FROM 2 PM
             SCA...PT ARENA TO PT REYES 0-10 NM FROM 2 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM FROM 2 PM

&&

$$

PUBLIC FORECAST: RWW
AVIATION/MARINE: DRP

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