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

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000
FXUS66 KMTR 181752
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
952 AM PST THU DEC 18 2014

.SYNOPSIS...A FEW LIGHT SHOWERS WILL LINGER INTO THE MORNING...
OTHERWISE THE AREA WILL SEE A BRIEF LULL IN PRECIPITATION TODAY.
THE NEXT SYSTEM TO BRING RAIN BACK TO THE AREA WILL MOVE IN LATE
THIS EVENING THROUGH FRIDAY. AFTER SOME RESIDUAL SHOWERS ON
SATURDAY...A RIDGE OF HIGH PRESSURE WILL BUILD OVER THE WEST COAST
RESULTING IN A DRYING TREND THROUGH EARLY NEXT WEEK.

&&

.DISCUSSION...AS OF 8:45 AM PST THURSDAY...RADAR CONTINUES TO SHOW
A FEW ECHOS THIS MORNING AND ACROSS THE CWA SEVERAL LOCATIONS HAVE
PICKED UP LIGHT AMOUNTS OF RAINFALL OVER THE PAST FEW HOURS. THE
SHOWER ACTIVITY WILL REMAIN SPOTTY THROUGH THE DAY ALTHOUGH WE
COULD SEE A FEW LOCATIONS GETTING CLOSE TO A TENTH. RAIN WILL BE ON
THE INCREASE TONIGHT INTO FRIDAY AS ANOTHER FRONT APPROACHES OUR
AREA AND THEN MOVES NW TO SE THROUGH THE REGION. ALTHOUGH THIS
WILL BE A FAR CRY FROM THE LARGER SYSTEMS WE HAVE HAD
RECENTLY...IT COULD STILL BRING A THIRD TO TWO THIRDS OF AN INCH
TO URBAN LOCATIONS BY FRIDAY EVENING WITH MORE THAN AN INCH OVER
THE NORTH BAY HILLS.

BIGGEST CONCERN RIGHT NOW WILL BE FRIDAY MORNING INTO THE EARLY
AFTERNOON HOURS ASSOCIATED WITH THE FRONT GOING ACROSS. COULD SEE A
BRIEF PERIOD OF MODERATE RAINFALL AT THAT TIME WITH A FEW HYDRO
ISSUES NOT OUT OF THE QUESTION. WINDS LOOK TO BE LIGHT FOR LOWER
ELEVATION SPOTS WITH SPEEDS OF 15 TO 25 MPH ABOVE 1000 FEET.

&&

.PREVIOUS DISCUSSION AS OF 3:30 AM THURSDAY...RESIDUAL LIGHT
SHOWERS ARE STILL OCCURRING WITH WEAK RADAR ECHOES MOVING FROM
WEST TO EAST ACROSS PORTIONS OF THE DISTRICT WITH THE STRONGER
ECHOES NOW WELL EAST OF OUR AREA. THESE ARE EXPECTED TO DIMINISH
THIS MORNING WITH A BREAK IN THE RAINY WEATHER EXPECTED THIS
AFTERNOON AS HIGH PRESSURE BRIEFLY BUILDS OVER THE AREA.

THIS BREAK WILL BE SHORT-LIVED...HOWEVER...AS THE NEXT SYSTEM IS DUE TO
ARRIVE THIS EVENING WITH LIGHT WARM FRONTAL RAINS SPREADING INTO
THE NORTH BAY AFTER SUNSET. THE MAIN FRONTAL BAND IS NOT EXPECTED TO
MOVE THROUGH UNTIL FRIDAY MORNING WITH BRIEF HEAVIER RAIN POSSIBLE
OVER THE NORTH BAY AS IT MOVES THROUGH...WITH LIGHTER RAIN SOUTH.
RESIDUAL SHOWERS ARE EXPECTED TO CONTINUE INTO SATURDAY MORNING.
RAINFALL AMOUNTS OF UP TO AN INCH IN THE NORTH BAY HILLS ARE
EXPECTED WITH A HALF INCH OR LESS EXPECTED ELSEWHERE.

HIGH PRESSURE IS THEN PROGGED TO BUILD ALONG THE COAST BEGINNING
ON SATURDAY. SOME OVERRUNNING MOISTURE COULD BRING A FEW SHOWERS TO
THE NORTH BAY LATE SATURDAY...OTHERWISE A DRYING TREND IS
INDICATED FOR THE DISTRICT THROUGH AT LEAST EARLY NEXT WEEK. THERE
ARE DIFFERENCES AMONGST THE MEDIUM RANGE MODEL SOLUTIONS WITH THE
GFS OFFERING A DRY SOLUTION THROUGH THE WEEK...WHILE BOTH THE ECMWF
AND GEM BRING IN AN INSIDE SLIDER TYPE TROUGH AFFECTING NORTHERN
CALIFORNIA LATE WEDNESDAY INTO THURSDAY WITH COOLER TEMPERATURES
AND POSSIBLE PRECIPITATION. IT SHOULD BE NOTED...HOWEVER...THAT BOTH
THE 6-10 DAY AND 8-14 DAY OUTLOOKS FROM THE CLIMATE PREDICTION
CENTER KEEP CALIFORNIA UNDER AN ABOVE NORMAL TEMPERATURE AND BELOW
NORMAL PRECIPITATION PATTERN THROUGH DECEMBER 23-27 AND 25-31
RESPECTIVELY.

&&

.AVIATION...AS OF 9:52 AM PST THURSDAY...FOR 18Z TAFS. STILL SOME
ISOLATED SHOWERS AROUND BUT MAINLY EXPECTING VFR WITH LOCAL MVFR
CIGS TODAY AS SOLAR HEATING WILL PRODUCE FRESH CLOUDS THIS
AFTERNOON ACROSS THE REGION. LIGHT SOUTHEAST FLOW CONTINUES AHEAD
OF NEXT FRONT. WARM FRONTAL SHOWERS BEGIN OVERNIGHT THEN STEADY
RAINS INTO THE BAY AREA FRIDAY MORNING WITH CONTINUED SOUTHEAST
WINDS.

VICINITY OF KSFO...MAINLY VFR CIGS TODAY BUT IN THE 3500 FOOT
RANGE WITH CONTINUED LIGHT SOUTHEAST WINDS. ANY BREAKS IN CLOUDS
THROUGH MIDDAY SHOULD BE FAIRLY SHORT LIVED AND CLOUDS IN GENERAL
SHOULD THICKEN LATER THIS AFTERNOON AND EVENING AHEAD OF NEXT FRONT.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...ISOLATED -SHRA POSSIBLE BUT WILL NOT
SHOW IN TAF. OTHERWISE VFR CIGS WILL CONTINUE IN THE 3500-5000
FOOT RANGE IN MOIST ONSHORE FLOW. GENERAL WINDS TO REMAIN
SOUTHEAST BUT COULD BRIEFLY TURN WEST THIS AFTERNOON BEFORE GOING
SOUTHEAST AGAIN OVERNIGHT AHEAD OF NEXT FRONT. STEADY RAINS ARRIVE
CLOSER TO 18Z FRIDAY.

&&

.MARINE...AS OF 9:52 AM PST THURSDAY...LIGHT TO MODERATE
SOUTHERLY FLOW WILL CONTINUE ALONG THE CENTRAL COAST THROUGH
FRIDAY. HAZARDOUS SEAS WILL DEVELOP FRIDAY AFTERNOON AS A LONG
PERIOD NORTHWESTERLY SWELL IMPACTS THE COASTAL WATERS. THE LARGEST
SWELL WILL BE NORTH OF PIGEON POINT AND OVER THE OUTER WATERS. THE
LARGE SWELL WILL DECREASE OVER THE WEEKEND.

&&

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

&&

$$

PUBLIC FORECAST: BELL
AVIATION/MARINE: RWW

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