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

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000
FXUS66 KMTR 202138
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
238 PM PDT SUN APR 20 2014

.SYNOPSIS...DRY AND MILD WEATHER WILL CONTINUE THROUGH MONDAY
AFTERNOON. A WEAK STORM WILL IMPACT THE AREA MONDAY NIGHT INTO
TUESDAY WITH A CHANCE OF LIGHT RAIN AND COOLER TEMPS. DRY WEATHER
AND NEAR NORMAL TEMPERATURES RETURN WEDNESDAY BEFORE MORE UNSETTLED
WEATHER AT THE END OF WEEK.

&&

.DISCUSSION...AS OF 02:30 PM PDT SUNDAY...MOSTLY SUNNY SKIES THIS
AFTERNOON AS STRATUS HAS ALMOST COMPLETELY CLEARED FROM THE COAST
AND JUST A FEW SMALL PATCHES OF CIRRUS WHISK THROUGH. THE ONSHORE
SFO-SAC GRADIENT IS A FAIR BIT WEAKER TODAY AT 1.2 MB OVER
YESTERDAYS 3.8. THIS COMBINED WITH SUBSIDENCE WARMING THE LOWER
ATMOSPHERE IS MAKING FOR A FAIRLY NICE SUNDAY ACROSS THE CWA.
TEMPS ARE RUNNING FIVE TO TEN DEGREES ABOVE WHERE THEY WERE THIS
TIME YESTERDAY. DOWNTOWN SAN FRANCISCO IS UP TO 73 DEGREES AT THIS
HOUR...THE FIRST IT HAS BEEN OVER 70 IN NEARLY TWO WEEKS.

AN APPROACHING COLD FRONT IS VISIBLE AS A WELL DEFINED LINE OF
CLOUDS ON SATELLITE IMAGERY WEST OF 130W. AS THE TROUGH GETS
CLOSER TOMORROW TEMPS WILL COOL ACROSS THE NORTHERN TWO THIRDS OF
THE CWA WHILE THE CENTRAL COAST REMAINS MILD. MODELS CONSISTENTLY
SHOW ONLY LIGHT PRECIP WITH THIS STORM BEGINNING MONDAY NIGHT AND
CONTINUING INTO TUESDAY AFTERNOON. RAINFALL AMOUNTS STILL LOOK TO
STAY BELOW A TENTH OF AN INCH IN PARTS OF SONOMA COUNTY AND ONLY A
FEW HUNDREDTHS OUTSIDE OF THE NORTH BAY. THE STORM SYSTEM WILL
BRING A COOLER AIRMASS DRAGGING DAYTIME HIGHS INTO THE 50S AND TO
MID 60S TUESDAY AFTERNOON.

DRY WEATHER SETS UP AND TEMPS REBOUND SLIGHTLY WEDNESDAY AND
THURSDAY AS A WEAK RIDGE MOVES THROUGH AHEAD OF ANOTHER STORM
SYSTEM.

MODELS ARE CONSISTENT IN BRINGING ANOTHER STORM INTO THE AREA AT
THE TAIL END OF THE WEEK HOWEVER THERE IS SOME DISAGREEMENT IN
TIMING AND IMPACTS. THE GFS CONTINUES TO BE MORE AGGRESSIVE HAVING
A DEEP TROUGH WITH RAIN STARTING FIRST THING FRIDAY MORNING AND A
SECOND STORM SUNDAY. ECMWF HAS BEEN MORE CONSERVATIVE WITH
RAINFALL AMOUNTS AND SLOWER IN TIMING. THE LATEST 12Z RUN DOES
CATCH UP THE TIMING MORE SHOWING RAIN STARTING SOME TIME ON
FRIDAY. GEFS ENSEMBLE PROBABILITY OF A TENTH OF INCH HAS DECREASED
SOMEWHAT SINCE YESTERDAY HOWEVER THE PROBABILITY OF MEASURABLE
REMAINS HIGH. ANOTHER STORM LOOKS POSSIBLE SUNDAY HOWEVER DETAILS
REMAIN UNCLEAR DUE TO DIVERGENT MODEL SOLUTIONS AT THIS TIME.

&&

.AVIATION...AS OF 10:35 AM PDT SUNDAY...SATELLITE IMAGERY SHOWS
THAT THE STRATUS HAS CLEARED TO JUST OFF THE MONTEREY BAY...AND
WISPS OF HIGH CLOUDS ARE ALSO STREAMING ACROSS THE STATE. VFR
CONDITIONS ARE EXPECTED THROUGH THE DAY WITH LOW CLOUDS DEVELOPING
THIS EVENING IN THE MONTEREY BAY TERMINALS.

VICINITY OF KSFO...VFR. MARINE LAYER INVERSION DEPTH MAY SUPPORT
SOME WESTERLY WIND GUSTS TO 20 KNOTS 21Z-04Z.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR TODAY. IFR CIGS DEVELOPING THIS
EVENING THROUGH EARLY MONDAY MORNING.

&&

.MARINE...AS OF 10:35 AM PDT SUNDAY...LARGE NW SWELL WITH LONGER
PERIODS WILL MOVE INTO THE WATERS TODAY AND TONIGHT. A HIGH SURF
ADVISORY IS IN EFFECT UNTIL 5 AM PDT MONDAY. NORTHWEST SWELL WILL
REACH 13 TO 15 FEET WITH A 16 SECOND SWELL PERIOD.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...HIGH SURF ADVISORY...COAST FROM SONOMA THROUGH MONTEREY COUNTY
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM UNTIL 6 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM UNTIL 6 PM
             SCA...ROUGH BAR ADVISORY FOR SF BAR UNTIL 5 AM

&&

$$

PUBLIC FORECAST: AC
AVIATION/MARINE: SIMS

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