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

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000
FXUS66 KMTR 211153
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
453 AM PDT MON APR 21 2014

.SYNOPSIS...DAYTIME TEMPERATURES WILL BE SLIGHTLY COOLER TODAY
WITH AN INCREASE IN MID TO HIGH LEVEL CLOUDS IN ADVANCE OF AN
APPROACHING FRONTAL BOUNDARY. LIGHT PRECIPITATION WILL BE POSSIBLE
TONIGHT THROUGH EARLY TUESDAY MORNING AS THE WEAK STORM SYSTEM
MOVES ACROSS THE REGION. DRY WEATHER AND NEAR NORMAL TEMPERATURES
RETURN WEDNESDAY BEFORE RAIN CHANCES RE-ENTER THE PICTURE BY THE
END OF WEEK.

&&

.DISCUSSION...AS OF 04:15 AM PDT MONDAY...GENERALLY CLEAR SKIES
PREVAIL ACROSS THE REGION THIS MORNING WITH ONLY A VERY WEAK
MARINE LAYER PRESENT. SATELLITE IMAGERY AT THIS HOUR SHOWS AN
INCREASE IN MID TO HIGH LEVEL CLOUDS IN ADVANCE OF A FRONTAL
BOUNDARY THAT WILL MOVE INTO THE PACIFIC NORTHWEST AND NORTHERN
CALIFORNIA THIS MORNING. WITH THE INCREASE IN CLOUDS MOVING IN AND
COOLING ALOFT...TEMPERATURES WILL BE COOLER ACROSS MUCH OF THE
REGION THIS AFTERNOON COMPARED TO THE WARM CONDITIONS OBSERVED
YESTERDAY AFTERNOON. THE WARMEST CONDITIONS TODAY WILL REMAIN
ACROSS THE CENTRAL COAST WITH A FEW INLAND LOCATIONS LIKELY
REACHING THE UPPER 70S TO NEAR 80 DEGREES.

THE MID/UPPER LEVEL SYSTEM WILL THEN MOVE INLAND AND BRING A
SLIGHT CHANCE OF PRECIPITATION TO NORTH BAY THIS EVENING AND THEN
SPREAD SOUTHWARD OVERNIGHT TONIGHT INTO EARLY TUESDAY MORNING. THE
LATEST FORECAST MODELS KEEP PRECIPITATION AMOUNTS VERY
LIGHT...GENERALLY ONLY A FEW HUNDREDTHS OF AN INCH FOR THOSE
LOCATIONS THAT DO RECEIVE RAINFALL. OTHERWISE...LOCATIONS SOUTH OF
THE SANTA CRUZ MOUNTAINS MAY ONLY PICK UP TRACE AMOUNTS OR NO
RAINFALL AT ALL FROM THIS MOISTURE STARVED SYSTEM. MUCH COOLER AND
DRIER CONDITIONS WILL THEN FILTER INTO CENTRAL CALIFORNIA ON
TUESDAY WITH AFTERNOON TEMPERATURES ONLY REACHING INTO THE UPPER
50S TO MID 60S.

DRY WEATHER WILL CONTINUE AND DAYTIME TEMPERATURES WARM SLIGHTLY
THROUGH MIDWEEK AS WEAK RIDGING BUILDS ALOFT. HOWEVER...WEAK
MID/UPPER LEVEL DISTURBANCES WILL BRING THE POSSIBILITY OF LIGHT
PRECIPITATION TO THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA FOR
THE LATTER HALF OF THE WEEK. WHILE THE BEST CHANCES FOR
PRECIPITATION REMAIN TO OUR NORTH...CANNOT RULE OUT LIGHT RAIN
ACROSS THE NORTH BAY WEDNESDAY NIGHT THROUGH THURSDAY.

FOR LATE IN THE WEEK INTO THE WEEKEND -- THE GFS AND GEM CONTINUE
TO SHOW A MUCH DEEPER MID/UPPER LEVEL TROUGH DIGGING SOUTHWARD AND
IMPACTING THE REGION. THIS WOULD BRING COOLER TEMPERATURES AND
WIDESPREAD LIGHT PRECIPITATION TO MUCH OF THE FORECAST AREA FRIDAY
THROUGH SATURDAY. HOWEVER...THE ECMWF IS LESS AGGRESSIVE WITH THIS
SYSTEM AND KEEPS A MORE ZONAL FLOW ACROSS CENTRAL CALIFORNIA.
THUS...RAIN CHANCES STAYING TO OUR NORTH. UNTIL MODEL CONSISTENCY
IMPROVES...WILL KEEP A SLIGHT CHANCE TO LOW END CHANCE OF
PRECIPITATION IN THE FORECAST FRIDAY THROUGH SATURDAY BEFORE
CONDITIONS DRY OUT AS RIDING RETURNS EARLY NEXT WEEK.

&&

.AVIATION...AS OF 4:45 AM PDT MONDAY...VFR. SKIES ARE CLEAR EXCEPT
FOR SOME HIGH CLOUDS DRIFTING IN FROM THE WEST. CLOUDINESS INCREASES
LATE TODAY INTO TUESDAY. SHOWERS POSSIBLE NORTH BAY LATE TONIGHT.

VICINITY OF KSFO...VFR.

KSFO BRIDGE APPROACH...VFR.

MONTEREY BAY AREA TERMINALS...VFR TODAY. LOW CLOUDS ARE POSSIBLE BY
THE EVENING.

&&

.MARINE...AS OF 4:45 AM PDT MONDAY...NORTHWEST SWELL ARE DECREASING
THIS MORNING AND ARE EXPECTED TO SLOWLY SUBSIDE THROUGH THE DAY.
SWELL PERIODS WILL ALSO BE DECREASING SLOWLY TO 13 SECONDS BY THIS
AFTERNOON.

A ROUGH BAR ADVISORY DOES CONTINUE THROUGH TONIGHT. ON TUESDAY NW
WINDS WILL INCREASE TO SMALL CRAFT CRITERIA FOR THE COASTAL WATERS.
NW WINDS OVER THE BAY WATERS WILL NOT BE AS GUSTY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
 .TDAY...HIGH SURF ADVISORY...EXPIRES AT 5 AM PDT THIS MORNING
  SCA...ROUGH BAR ADVISORY FOR SF BAR

&&

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: CANEPA

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