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

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000
FXUS66 KMTR 270444
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
944 PM PDT THU MAR 26 2015

.SYNOPSIS...A RETURN OF COASTAL FOG AND LIGHT ONSHORE FLOW WILL
MEAN COOLER TEMPERATURES ON FRIDAY...ESPECIALLY NEAR THE COAST.
ONSHORE FLOW WILL WEAKEN BY SATURDAY... AND RESULT IN MOSTLY CLEAR
SKIES AND WARMER THAN NORMAL TEMPERATURES OVER THE WEEKEND.
COOLING IS THEN EXPECTED DURING THE FIRST HALF OF NEXT WEEK. DRY
WEATHER WILL CONTINUE WITH NO RAIN IN SIGHT THROUGH THE END OF THE
MONTH

&&

.DISCUSSION...AS OF 8:55 PM PDT THURSDAY...SUBSIDENCE WARMING
OCCURRED UNDER A WEST COAST RIDGE TODAY. THE 00Z OAK SOUNDING
SHOWS THAT THE AIRMASS BELOW 900 MB WARMED BY AS MUCH AS 6 DEGREES
C SINCE YESTERDAY. IN ADDITION...LIGHT OFFSHORE FLOW DEVELOPED
LAST NIGHT AND PERSISTED THROUGH EARLY AFTERNOON HOURS OF TODAY.
TODAY`S SEABREEZE WAS WEAK AND DEVELOPED LATE. THESE DEVELOPMENTS
RESULTED IN SEVERAL DAILY HIGH TEMPERATURE RECORDS ACROSS OUR
REGION TODAY...INCLUDING SAN JOSE WITH A HIGH OF 85 AND SALINAS
AIRPORT AT 90. THE SALINAS AIRPORT CAME WITHIN TWO DEGREES OF
MATCHING ITS RECORD HIGH FOR THE ENTIRE MONTH OF MARCH...WHICH WAS
SET JUST A DOZEN DAYS AGO ON MARCH 14.

LOW CLOUDS AND FOG BEGAN TO DEVELOP OVER THE COASTAL WATERS THIS
AFTERNOON AND LOW CLOUDS/FOG QUICKLY FILLED IN ALONG MOST OF OUR
COAST BY EARLY EVENING. A FORECAST UPDATE WAS COMPLETED EARLIER
THIS EVENING TO INCREASE CLOUD COVER AND ADD FOG TO COASTAL AREAS
OVERNIGHT AND INTO FRIDAY MORNING.

ONSHORE FLOW REMAINS WEAK AT THIS TIME AND INDICATIONS ARE THAT
THE MARINE LAYER IS QUITE SHALLOW. THUS...EXPECT MOST OF THE LOW
CLOUDS AND FOG TO REMAIN CONFINED TO AREAS NEAR THE OCEAN
THROUGH EARLY FRIDAY. PATCHY DENSE FOG IS LIKELY OVERNIGHT THROUGH
MID MORNING FRIDAY.

BOTH THE NAM AND WRF MODEL OUTPUT INDICATE INCREASING ONSHORE FLOW
DURING THE DAY ON FRIDAY AS A SHORTWAVE TROUGH APPROACHES THE PAC
NW AND FAR NORTHERN CA. THIS WILL MEAN PERSISTENT LOW CLOUDS NEAR
THE COAST TOMORROW...WITH SOME LOW CLOUDS POSSIBLY PRESSING INLAND
AS THE DAY PROGRESSES. CONSEQUENTLY...WE CAN EXPECT COOLER
CONDITIONS IN MOST AREAS TOMORROW...ESPECIALLY NEAR THE COAST AND
IN THE COASTAL VALLEYS WHERE HIGH TEMPERATURES WILL LIKELY BE 10
TO 15 DEGREES COOLER COMPARED TO TODAY.

TOMORROW`S COOL-DOWN WILL BE SHORT-LIVED. THE SHORTWAVE TROUGH
WILL MOVE WELL OFF TO OUR EAST BY LATE FRIDAY NIGHT AND THE 00Z
NAM DEVELOPS LIGHT OFFSHORE FLOW ALOFT BY SATURDAY MORNING. THIS
SHOULD RESULT IN CLEARING IN MOST AREAS BY MIDDAY SATURDAY AS
WELL AS SLIGHT WARMING ON SATURDAY. MOSTLY CLEAR AND MILD
CONDITIONS ARE EXPECTED TO CONTINUE INTO SUNDAY AS WELL.

ANOTHER SHORTWAVE TROUGH IS FORECAST TO APPROACH THE COAST TO OUR
NORTH NEXT MONDAY. THIS WILL RESULT IN MODEST COOLING DURING THE
FIRST HALF OF THE WORK WEEK. ALL PRECIP WITH THE MONDAY SYSTEM IS
EXPECTED TO REMAIN WELL TO OUR NORTH. IN FACT...THE MEDIUM RANGE
MODELS AGREE THAT DRY CONDITIONS WILL PREVAIL THROUGH THE END OF
MARCH...AND THROUGH AT LEAST THE FIRST FEW DAYS OF APRIL AS WELL.

&&

.AVIATION...AS OF 9:45 PM PDT THURSDAY...FOG HAS DEVELOPED ALONG
THE COAST THIS EVENING AND WILL IMPACT MRY AND SNS. WARM AND DRY
AIRMASS OVER THE INTERIOR WILL KEEP FOG AND LOW CIGS OUT OF THE
SFO BAY AREA.

VICINITY OF KSFO...VFR THROUGH FRIDAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR FOR CIGS AND VSBYS THROUGH 12Z.
DRAINAGE WIND FROM THE SNS VALLEY EXPECTED TO PUSH FOG OUT AFTER
12Z.


&&

.MARINE...AS OF 9:45 PM PDT THURSDAY...A WEAK DISTURBANCE WILL
MOVE THROUGH THE AREA ON FRIDAY RESULTING IN LIGHTER WINDS. HIGH
PRESSURE WILL BUILD OFF THE CALIFORNIA COAST BEHIND THE SYSTEM
BRINGING INCREASING NORTHWEST WINDS FRIDAY NIGHT AND LASTING
THROUGH EARLY NEXT WEEK. SOUTHERLY SWELLS GENERATED FROM A SOUTH
PACIFIC TROPICAL CYCLONE WILL ARRIVE ALONG THE COAST FRIDAY AND
CONTINUE THROUGH THE WEEKEND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...NONE.

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION: W PI
MARINE: BELL

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