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

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000
FXUS66 KMTR 222143
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
243 PM PDT MON SEP 22 2014

.SYNOPSIS...NEAR SEASONAL CONDITIONS WILL CONTINUE ACROSS THE SAN
FRANCISCO AND MONTEREY BAY AREA EARLY THIS WEEK. COOLER WEATHER
AND CHANCES FOR RAINFALL ARE THEN EXPECTED BY MIDWEEK AS AN UPPER
LEVEL SYSTEM IMPACTS THE REGION.

&&

.DISCUSSION...AS OF 02:42 PM PDT MONDAY...MOSTLY SUNNY CONDITIONS
PREVAIL ACROSS THE REGION THIS AFTERNOON ALONG WITH TEMPERATURES
NEAR SEASONAL AVERAGES. THIS IS A RESULT OF A WEAK MID/UPPER
LEVEL RIDGE THAT HAS DEVELOPED AHEAD OF AN APPROACHING TROUGH
THAT WILL BRING RAIN CHANCES TO THE REGION BY MIDWEEK. FOR THE
NEXT FEW DAYS...EXPECT AFTERNOON TEMPERATURES NEAR NORMAL WHILE
OVERNIGHT TEMPERATURES WILL CONTINUE TO RUN A FEW TO SEVERAL
DEGREES ABOVE AVERAGE WITH HIGHER THAN NORMAL HUMIDITY. IN
ADDITION...WITH A MARINE LAYER AROUND 2000FT...COASTAL CLOUDS
WILL LIKELY RETURN DURING THE OVERNIGHT AND MORNING HOURS.

TEMPERATURES THEN COOL TO BELOW SEASONAL AVERAGES FOR THE LATTER
HALF OF THE WEEK AS A MID/UPPER LEVEL TROUGH IMPACTS THE REGION.
THE SYSTEM WILL FIRST BRING PRECIPITATION TO THE PACIFIC
NORTHWEST TUESDAY AND BEING TO DIG SOUTHWARD WEDNESDAY INTO
THURSDAY. THE FORECAST MODELS INDICATE CHANCES FOR PRECIPITATION
WILL ENTER THE PICTURE OVER THE NORTH BAY AS EARLY AS TUESDAY
NIGHT AS LIGHT RAIN. RAIN SHOWERS WILL THEN DEVELOP AND INCREASE
OVER THIS REGION THROUGH WEDNESDAY EVENING AND BEGIN TO SPREAD
SOUTHWARD WEDNESDAY NIGHT. AT THIS TIME...THE BEST CHANCES FOR
MEASURABLE PRECIPITATION WILL BE NORTH OF SAN FRANCISCO WITH RAIN
SHOWERS POSSIBLE AS FAR SOUTH AS THE SANTA CRUZ MOUNTAINS.
FURTHER SOUTH AND ESPECIALLY INLAND...RAIN SHOWERS WILL BE MORE
SCARCE. BY TOMORROW...THE HIGH RESOLUTION MODELS WILL BECOME MORE
USEFUL IN HELPING WITH FORECASTING THE RAINFALL AMOUNTS ACROSS
THE REGION...SO STAY TUNED.

THE UPPER LEVEL TROUGH IS FORECAST TO REMAIN ACROSS MUCH OF THE
WEST COAST THROUGH SATURDAY AND RESULT IN BELOW AVERAGE
TEMPERATURES. HOWEVER...RAIN CHANCES DIMINISH LATE THURSDAY INTO
FRIDAY AS 850MB WINDS TURN MORE NORTHERLY AND AVAILABLE MOISTURE
ALOFT BECOMES LIMITED. AS THE TROUGH EXITS EASTWARD LATE IN THE
WEEKEND...THE MID/UPPER LEVEL RIDGE BUILDS OVER THE EASTERN
PACIFIC AND WILL RESULT IN DRY WEATHER CONDITIONS AND SLIGHTLY
WARMER TEMPERATURES BY EARLY NEXT WEEK.

&&

.AVIATION...AS OF 10:30 AM PDT MONDAY...THE MARINE LAYER REMAINS
AROUND 2000 FT THIS MORNING. NORTHWEST FLOW IS SCOURING STRATUS
FROM THE BAY AREA WHILE ALSO DRIVING IT FURTHER INTO THE SANTA
CLARA VALLEY AND MONTEREY PENINSULA. EXPECT CLEARING AT ALL BUT
MRY BEFORE MORNING IS OUT. VFR THIS AFTERNOON WITH MOSTLY LIGHT
WINDS. SOME PATCHY STRATUS TO STAY ALONG THE COAST TODAY AND
LIKELY TO RETURN TO THE TERMINALS TONIGHT.

VICINITY OF KSFO...BECOMING VFR MOMENTARILY. ONSHORE WINDS TO
AROUND 15 KT THIS AFTERNOON. STRATUS TO RETURN TONIGHT LATE
EVENING.

KSFO BRIDGE APPROACH...SIMILAR  TO KSFO.

MONTEREY BAY AREA TERMINALS...SNS TO CLEAR IN THE NEXT HOUR AS
CIGS ERODE IN THE SALINAS VALLEY. NW FLOW TO MAINTAIN CIGS AT MRY
INTO EARLY AFTERNOON. THEN VFR THROUGH MID TO LATE AFTERNOON.

&&

.CLIMATE...AUTUMN OFFICIALLY BEGINS (AUTUMNAL EQUINOX) AT 7:29 PM
PDT TODAY.

&&

.MARINE...AS OF 02:42 PM PDT MONDAY...MOSTLY LIGHT NORTHWEST WINDS
WILL CONTINUE OVER THE COASTAL WATERS AS HIGH PRESSURE REMAINS
OVER THE EASTERN PACIFIC. MID WEEK A COLD FRONT WILL MOVE THROUGH
THE REGION AND MODERATE PERIOD NORTHWESTERLY SWELL WILL BUILD.

&&

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

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: AC

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