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

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000
FXUS66 KMTR 160448
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
948 PM PDT MON SEP 15 2014

.SYNOPSIS...A GRADUAL COOLING TREND WILL CONTINUE OVER INLAND
AREAS ON TUESDAY AHEAD OF AN APPROACHING TROUGH. THIS SYSTEM WILL
BRING A SLIGHT CHANCE OF SHOWERS TO THE NORTH BAY AND SAN
FRANCISCO BAY AREA LATE WEDNESDAY INTO EARLY THURSDAY. SHOWER CHANCES
THEN END AND TEMPERATURES REBOUND FOR THE UPCOMING WEEKEND.

&&

.DISCUSSION...AS OF 9:47 PM PDT MONDAY...SKIES ARE MOSTLY CLEAR
THIS EVENING EVEN THOUGH THE WIND FLOW IS DISTINCTLY ONSHORE WITH
CYCLONIC FLOW ALOFT OVER THE OCEAN. THE SST ARE NOW A SOLID 65
DEGREES...UNSEASONABLY WARM AND THE MARINE INVERSION LAYER ISN`T
REFORMING LIKE IT USUALLY DOES WITH LARGER SURFACE TO 850 MB DELTA T.
ANYWAY STILL EXPECT MARINE CLOUDS TO SLOWLY REFORM OVERNIGHT AND
THROUGH MORNING WITH INCREASING WESTERLY WIND FLOW AHEAD OF THE
SYSTEM.

BATCH OF MOISTURE CLEARLY SHOWS UP ON IR SATELLITE OUR NEAR
35N/135W WITH JET STREAM ENERGY DROPPING DOWN THE BACKSIDE OF THE
TROUGH. THIS WILL SLOW ANY EASTWARD PROGRESSION AS WILL TS ODILE
AND THE RIDGE OVER THE WESTERN US.

MAIN RAIN BAND WILL STAY FOCUSED NORTH OF THE BAY AREA AND HEAD
TOWARDS CAPE MENDOCINO BY WEDS AFTERNOON. HOWEVER AS THIS OCCURS
THE SYSTEM WILL STALL OUT AND NOW PRETTY GOOD MODEL CONSENSUS FOR
GENERATING SOME LIGHT AND SPOTTY SHOWERS OVER THE NORTH BAY LATER
WEDS EVENING INTO EARLY THURSDAY MORNING. ANY QPF LOOKS TO BE ON
THE ORDER OF A FEW HUNDREDTHS WITH LITTLE OR NO CHANCE OF PRECIP
SOUTH OF THE GOLDEN GATE (OR PERHAPS THE SANTA CRUZ MOUNTAINS).
MOS GUIDANCE HAS POPS AS HIGH AS 40% FOR SANTA ROSA TO AROUND 20%
FOR SAN JOSE BUT AGAIN LITTLE HOPE FOR MORE THAN A FEW LIGHT RAIN
SHOWERS.

THE JUICY AND SOMEWHAT PROMISING WEATHER SYSTEM GETS CUT-OFF AND
BECOMES MORIBUND BY THURSDAY AFTERNOON AS RIDGING BUILDS IN FROM
THE WEST. THE UPPER LOW WILL DROP DOWN THE COAST AND THE BAY AREA
WILL BECOME UNDER THE INFLUENCE OF NORTHEASTERLY FLOW AROUND THE
UPPER LOW AND BUILDING HIGH PRESSURE FROM THE WEST. THIS WILL SET
THE STAGE FOR A SUNNY AND WARM TO HOT WEEKEND WITH 850 MB TEMPS
AROUND 24 CELSIUS...THERMAL TROUGH NEAR THE COAST...590 DM HIGH
OVER NORCAL AND SYNOPTIC EASTERLY FLOW OVER CENTRAL CALIFORNIA
ROTATING AROUND THE UPPER LOW.


&&

.AVIATION...AS OF 4:45 PM PDT MONDAY...HIGH PROB VFR WILL CONTINUE
AT AREA TERMINALS THIS EVENING. VISIBLE IMAGERY SHOWS CLEAR SKIES
OVER AREA. HOWEVER LATE TONIGHT LOW CLOUDS ARE FORECAST TO
REDEVELOP AND SOME INLAND MOTION OF THE CLOUDS ARE POSSIBLE BUT IT
SHOULD BE SOMEWHAT LIMITED DUE TO WEAK ONSHORE WINDS.

VICINITY OF KSFO...VFR THROUGH THE EVENING. WEST WIND GUSTS TO 20
KT TIL 04Z. LOW CLOUDS ARE FORECAST TO ARRIVE LATE AT NIGHT. VFR
RETURNS LATE TUESDAY MORNING.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...MODERATE TO HIGH CONFIDENCE VFR WILL
HOLD THIS EVENING. LOW CLOUDS ARE EXPECTED TO DEVELOP LATE THIS
EVENING. IFR FORECAST TO DEVELOP 07Z-09Z.

&&

.MARINE...AS OF 09:07 AM PDT MONDAY...GENERALLY LIGHT ONSHORE FLOW
AND GENTLE SEAS WILL CONTINUE THROUGH MUCH OF THE UPCOMING WORK
WEEK. MEANWHILE...A LONG PERIOD SOUTHWEST SWELL WILL BEGIN TO
BUILD INTO THE WATERS AND CONTINUE THROUGH MIDWEEK.

&&

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

&&

$$

PUBLIC FORECAST: RWW
AVIATION: CANEPA
MARINE: BELL

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