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

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000
FXUS66 KMTR 290437
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
937 PM PDT SAT MAR 28 2015

.SYNOPSIS...MUCH ABOVE NORMAL TEMPERATURES WILL CONTINUE INTO
SUNDAY WITH RECORD HIGH TEMPERATURES POSSIBLE ONCE AGAIN. A COOLING
TREND IS THEN FORECAST FROM MONDAY THROUGH WEDNESDAY. DRY WEATHER
IS EXPECTED TO PERSIST THROUGH THE FORECAST PERIOD.

&&

.DISCUSSION...AS OF 8:55 PM PDT SATURDAY...A RELATIVELY STRONG
NORTH-SOUTH SURFACE PRESSURE GRADIENT ACROSS NORTHERN CALIFORNIA
GREATLY REDUCED ONSHORE FLOW TODAY...ALLOWING THE AIRMASS OVER OUR
AREA TO WARM AND DRY. LOCATIONS IN CLOSE PROXIMITY TO THE OCEAN
SAW AFTERNOON HIGHS IN THE 60S....BUT 70S AND LOWER 80S WERE
COMMONPLACE ELSEWHERE. A FEW OF THE WARMEST INLAND VALLEYS POSTED
HIGHS IN THE MID AND UPPER 80S. FIVE LOCATIONS MET OR EXCEEDED
THEIR RECORD HIGHS FOR THE DAY INCLUDING
OAKLAND...GILROY...NAPA...SAN RAFAEL...AND LIVERMORE.

SKIES REMAIN MOSTLY CLEAR THIS EVENING...WITH NO EVIDENCE ON
SATELLITE OF COASTAL LOW CLOUDS AND FOG. A FEW PATCHES OF FOG/LOW
CLOUDS MAY DEVELOP ALONG THE COAST OVERNIGHT...BUT WITH THE ACV-
SFO SURFACE PRESSURE GRADIENT CURRENTLY AT A ROBUST 8 MB...IT`S
LIKELY THAT INLAND AREAS WILL REMAIN CLEAR.

SUNDAY SHOULD BE A DAY MUCH LIKE TODAY. PERIODS OF HIGH CLOUDS ARE
EXPECTED...BUT THESE CLOUDS SHOULD BE THIN AND NOT IMPACT
TEMPERATURES VERY MUCH. 850 MB TEMPERATURES ARE FORECAST TO WARM
SLIGHTLY FROM TODAY...BUT THE NORTH-SOUTH SURFACE PRESSURE GRADIENT
IS PROJECTED TO EASE SOMEWHAT. THE NET EFFECT SHOULD BE
TEMPERATURES NEAR PERSISTENCE. MOS GUIDANCE WAS TOO COOL
TODAY...IN SOME CASES MUCH TOO COOL...AND BELIEVE THE SAME IS
LIKELY TO BE THE CASE TOMORROW. MAX TEMPERATURES FOR TOMORROW WERE
BUMPED SLIGHTLY HIGHER IN AN EARLY EVENING FORECAST UPDATE...TO
PUT THEM MORE IN LINE WITH PERSISTENCE.

THE MODELS AGREE THAT AN UPPER LEVEL TROUGH WILL APPROACH THE WEST
COAST BY LATE MONDAY. THE APPROACH OF THIS TROUGH WILL TRIGGER AN
INCREASE IN ONSHORE FLOW ON MONDAY AND BEGIN A COOLING TREND. THAT
COOLING TREND IS EXPECTED TO CONTINUE THROUGH MIDWEEK AS THE
UPPER TROUGH SETTLES IN ACROSS THE WEST. TEMPERATURES WILL DROP
BACK TO AROUND NORMAL BY TUESDAY...AND EVEN A BIT BELOW NORMAL BY
WEDNESDAY. ALL PRECIPITATION WITH THIS TROUGH IS EXPECTED TO
REMAIN WELL NORTH OF OUR AREA.

DRY WEATHER CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE NEXT
SEVEN DAYS. THE MEDIUM RANGE MODELS AGREE THAT A COLD TROUGH DROPPING
IN FROM THE GULF OF ALASKA LATE NEXT WEEK MAY PRODUCE RAIN IN OUR
AREA BY THE FIRST WEEKEND OF APRIL.

&&

.AVIATION...AS OF 9:30 PM PDT SATURDAY...A DRY NORTHERLY WIND FLOW
WILL TEND TO KEEP VFR GOING AREA-WIDE FOR THE PERIOD. THE ACV-SFO
GRADIENT IS NEAR 8 MB AND THE UKI-STS GRADIENT IS 3 MB. STS REPORTS
A NORTH WIND AT 10 KNOTS. THE NORTH WIND AT STS COULD BECOME A LITTLE
GUSTY AT TIMES OVERNIGHT BUT ALSO WEIGHTED IN THE FORECAST IS THE
TENDENCY FOR THE SURFACE WINDS TO DE-COUPLE UNDER NIGHT-TIME COOLING.
THE 00Z NAM MODEL APPEARS TO BE UNDER-FORECASTING TONIGHT`S NORTHERLY
GRADIENTS BY APPROX 1-3 MB...WHICH MAY CARRY OVER INTO SUNDAY.
ALSO...7-8 MB OF OFFSHORE GRAD FROM WMC-SFO APPEARS VERY LIKELY LATE
TONIGHT AND EARLY SUNDAY MORNING LIKELY HELPING TO FURTHER DIMINISH
THE ONSHORE WINDS. IN SUMMARY IT LOOKS LIKE A HIGH CONFIDENCE VFR
FORECAST FOR THE PERIOD THE ONLY EXCEPTION IS THAT THERE MAY BE A
FEW SMALL PATCHES OF LOW CLOUDS AND/OR FOG OVER THE SOUTHERN MONTEREY
BAY AREA BRIEFLY VERY LATE TONIGHT AND/OR EARLY SUNDAY MORNING.

VICINITY OF KSFO...VFR. RECENT OBS INDICATE WESTERLY WIND GUSTS
STILL REACHING TO 20 KNOTS. SURFACE WINDS SHOULD TEND TO SETTLE
SLOWLY OVERNIGHT...A LITTLE SLOWER THAN PREVIOUSLY FORECASTED.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...SO FAR SO GOOD VFR CONTINUES TO HOLD
THIS EVENING...BUT AS DISCUSSED THERE MAY BE A FEW SMALL PATCHES
OF LOW CLOUDS AND/OR FOG VERY LATE TONIGHT AND/OR EARLY SUN MORNING.
24 HOUR TRENDS INDICATE DECENT DRYING OF THE AIR MASS THIS AREA
INCLUSIVE SO THE TAFS MAINTAIN OPTIMISTIC WITH VFR FOR THE OVERNIGHT
HOURS AND SUNDAY.

&&

.MARINE...AS OF 8:48 PM PDT SATURDAY...STRONG AND GUSTY NW WINDS WILL
CONTINUE OVER THE COASTAL WATERS THIS WEEKEND AND NEXT WEEK. HIGH
PRESSURE WILL REMAIN PARKED OVER THE EASTERN PACIFIC THROUGH THE
PERIOD. THE STRONG WINDS WILL PRODUCE FRESH AND SHORT PERIOD SEAS.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 3 AM
             SCA...PT ARENA TO PT REYES 0-10 NM
             SCA...PT REYES TO PIGEON PT 0-10 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
             SCA...PT ARENA TO PT REYES 10-60 NM
             SCA...PT REYES TO PIGEON PT 10-60 NM
             SCA...PIGEON PT TO PT PINOS 10-60 NM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM
             SCA...MONTEREY BAY UNTIL 11 PM

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: CANEPA

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