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

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000
FXUS66 KMTR 281147
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
347 AM PST WED JAN 28 2015

.SYNOPSIS...DRY CONDITIONS ARE EXPECTED THROUGH SUNDAY MORNING...WITH
CHANCES OF SOME LIGHT RAIN THEN DEVELOPING OVER THE NORTHERN HALF
OF THE DISTRICT BEGINNING SUNDAY AFTERNOON AND EVENING...AND CONTINUING
INTO THE FIRST PART OF NEXT WEEK. BY MIDWEEK DRY CONDITIONS ARE
AGAIN PROJECTED TO PREVAIL ACROSS THE AREA. TEMPERATURES WILL GENERALLY
REMAIN ABOVE SEASONAL NORMS...WARMEST ON SATURDAY.

&&

.DISCUSSION...AS OF 3:30 AM PST WEDNESDAY...CLEAR TO PARTLY CLOUDY
SKIES PREVAIL ACROSS THE DISTRICT ALONG WITH SOME PATCHES OF FOG
IN THE NORTH BAY VALLEYS. LOWER ELEVATION TEMPERATURES ARE
GENERALLY IN THE MID 40S TO LOWER 50S.

THE WEAK UPPER LEVEL DISTURBANCE THAT BROUGHT SOME SHOWERS TO MORE
SOUTHERN PORTIONS OF OUR DISTRICT ON TUESDAY HAS NOW WEAKENED AND
MOVED NORTHEASTWARD INTO THE GREAT BASIN. ALTHOUGH SOUTHWESTERLY
FLOW ALOFT WILL CONTINUE OVER US FOR THE NEXT COUPLE OF DAYS...LATEST
MODEL OUTPUT REMAINS IN EXCELLENT AGREEMENT THAT ALL PRECIP ASSOCIATED
WITH THE NEXT DISTURBANCE WILL STAY WELL TO OUR SOUTHEAST WHEN IT
MOVES INLAND THURSDAY NIGHT AND FRIDAY. DRY CONDITIONS ARE THUS
EXPECTED TO PREVAIL DISTRICTWIDE THROUGH THE END OF THE WEEK AND
INTO THE WEEKEND. THIS WOULD THEN BRING TO A CLOSE AN HISTORICALLY
DRY MONTH OF JANUARY. FOR DOWNTOWN SAN FRANCISCO FOR EXAMPLE...THIS
WOULD THEN BECOME THE FIRST JANUARY SINCE PRECIPITATION RECORDS
BEGAN IN 1850...165 YEARS AGO...FOR THERE TO BE NO MEASURABLE
PRECIPITATION AT ALL.

NOT MUCH TEMPERATURE CHANGE IS EXPECTED FOR THE NEXT COUPLE OF
DAYS WITH DAYTIME TEMPERATURES GENERALLY CONTINUING TO BE ABOVE
NORMAL.

FRIDAY NIGHT AND SATURDAY...HIGH PRESSURE AT THE SURFACE AND ALOFT
WILL BUILD ALONG THE WEST COAST AND THEN INTO THE NORTHERN GREAT
BASIN ALONG WITH WARMING OF THE AIR MASS OVER US. THE NET RESULT
WILL BE CLEAR SKIES AND AFTERNOON TEMPERATURES LOCALLY GETTING
BACK UP INTO THE 70S.

IN THE LONGER RANGE...LATEST RUNS OF BOTH THE ECMWF AND GFS MODELS
FLATTEN THE UPPER LEVEL RIDGE AND THEN DRAG A BAND OF LIGHT RAIN
ASSOCIATED WITH THE TAIL END OF A WEAK PACIFIC FRONTAL SYSTEM INTO
THE NORTHERN PORTION OF OUR DISTRICT. TIMING HOWEVER DIFFERS...
WITH THE 00Z ECMWF OUTPUT FOCUSING ON THE SUNDAY AFTERNOON AND
EVENING TIME FRAME WHILE BOTH THE 00Z AND JUST REC`D 06Z GFS
OUTPUT DELAYS IT UNTIL LATER SUNDAY NIGHT INTO MONDAY. BOTH ARE IN
AGREEMENT THOUGH THAT TOTALS WILL BE LESS THAN 1/4 INCH...AND THAT
RENEWED LARGE SCALE UPPER LEVEL RIDGE DEVELOPMENT WILL OCCUR OVER
THE WEST COAST AS WE HEAD INTO THE MIDDLE OF NEXT WEAK...AND THUS DRY
CONDITIONS RETURNING DISTRICTWIDE.

&&

.AVIATION...AS OF 3:46 AM PST WEDNESDAY...HIGH PRESSURE WILL
CONTINUE TO BUILD OVER THE CENTRAL COAST TODAY WITH LIGHT OFFSHORE
FLOW AT THE SURFACE. THE COMBINATION OF LIGHT OFFSHORE FLOW AND HIGH
PRESSURE ALOFT WILL MAINTAIN CLEAR SKIES AT THE TERMINALS TODAY WITH
THE EXCEPTION OF KSTS WHICH MAY EXPERIENCE A PERIOD OF DENSE FOG
THIS MORNING.

VICINITY OF KSFO...VFR AND GENERALLY LIGHT WINDS ARE EXPECTED TO
PREVAIL TODAY WITH A GENTLE SEA BREEZE THIS AFTERNOON.

CONFIDENCE IS HIGH.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR AND GENERALLY LIGHT WINDS ARE
EXPECTED TO PREVAIL TODAY. EASTERLY WINDS ARE EXPECTED TO CONTINUE TO
PERSIST INTO THE LATE MORNING HOURS WITH A GENTLE SEA BREEZE THIS
AFTERNOON.

CONFIDENCE IS HIGH.

&&

.MARINE...AS OF 03:46 AM PST WEDNESDAY...GENERALLY LIGHT WINDS ARE
EXPECTED TO PERSIST OVER THE COASTAL WATERS TODAY. WINDS WILL
BEGIN TO STRENGTHEN OUT OF THE NORTHWEST THURSDAY AS A THERMAL
TROUGH DEVELOPS ALONG THE COAST...MAINTAINING MODERATE NORTHERLY
WINDS THROUGH FRIDAY. THE THERMAL TROUGH IS ANTICIPATED TO SLIDE
OFFSHORE THIS WEEKEND...RESULTING IN LIGHT WINDS ACROSS THE
WATERS. A LONG PERIOD SWELL WILL MOVE INTO THE COASTAL WATERS
THURSDAY MORNING.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...NONE.

$$

PUBLIC FORECAST: BLIER
AVIATION/MARINE: LARRY

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