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

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000
FXUS66 KMTR 250259
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
759 PM PDT THU APR 24 2014

.SYNOPSIS...A STORM SYSTEM WILL BRING COOLER TEMPERATURES AND
CHANCES FOR PRECIPITATION TO THE REGION LATE TONIGHT THROUGH
FRIDAY. ANOTHER WEAKER SYSTEM COULD BRING RAIN CHANCES SATURDAY
NIGHT AND SUNDAY. ABOVE NORMAL TEMPERATURES ARE EXPECTED NEXT WEEK
AS HIGH PRESSURE BUILDS OVER THE REGION.

&&

.DISCUSSION...AS OF 8:00 PM PDT THURSDAY...A COLD FRONT STRETCHED
ACROSS NORTHERN CALIFORNIA WILL GRADUALLY SLIDE SOUTH BRINGING
RAIN TO THE REGION LATE TONIGHT AND FRIDAY. THERE EXISTS A
POSSIBILITY OF THUNDERSTORMS FRIDAY AS THE AN UPPER LEVEL LOW AND
THE ACCOMPANYING UNSTABLE AIRMASS MOVE DIRECTLY ACROSS THE CWA.

CURRENTLY TEMPERATURES REMAIN IN THE 60S ACROSS MOST LOCATIONS
WITH MODERATE AND LOCALLY GUSTY WESTERLY WINDS. CEILINGS ARE
GRADUALLY LOWERING FROM NORTH TO SOUTH ACROSS THE DISTRICT. THE
CHANCE OF RAIN WILL INCREASE THROUGH THE NIGHT WITH A WET COMMUTE
EXPECTED FRIDAY MORNING ACROSS THE CWA. RAINFALL TOTALS WILL NOT
BE VERY LARGE WITH A FEW HUNDREDTHS TO A FEW TENTS EXPECTED. THE
HILLS AND MOUNTAINS WILL RECEIVE THE HIGHEST AMOUNTS. THE MAIN
CONCERN FOR FRIDAY WILL BE THE THREAT OF THUNDERSTORMS IN RESPONSE
TO THE ALIGNMENT OF THE JET MAX AND THE UNSTABLE AIRMASS THAT WILL
ACCOMPANY THE UPPER LOW. BUFFER SOUNDING DATA DEPICTS CAPE IN
EXCESS OF 500 J/KG WHICH IS SIGNIFICANT IN THIS AREA.
THUNDERSTORMS THAT DO DEVELOP WILL BE CAPABLE OF PRODUCING GUSTY
WINDS AND SMALL HAIL AND WILL NEED TO BE MONITORED CAREFULLY.

FROM PREVIOUS DISCUSSION...STORM PREDICTION CENTER EXPANDED THEIR
GENERAL MENTION OF THUNDERSTORMS TO INCLUDE MUCH OF CA NORTH OF
SAN FRANCISCO.

PRECIP CHANCES AND THUNDERSTORM THREAT DIMINISHES QUICKLY AFTER
00Z SATURDAY AS THE BEST FORCING MOVES EAST AND DRIER AIR ALOFT
FILLS IN FROM THE WEST. DRY WEATHER IS EXPECTED FOR MUCH OF
SATURDAY...BUT BELOW NORMAL TEMPERATURES ARE BEING FORECAST. HIGHS
ON SATURDAY WILL BE IN THE UPPER 50S TO MID 60S...HIGH ELEVATIONS
IN THE 40S TO 50S.

ANOTHER WEAK SYSTEM WILL MOVE IN SATURDAY NIGHT INTO SUNDAY
MORNING. LOW CONFIDENCE FOR THIS POTENTIAL PRECIP EVENT...BUT
GIVEN RECENT MODEL OUTPUT DECIDED TO INTRODUCE LIGHT PRECIP LATE
SATURDAY NIGHT/SUNDAY MORNING. PERSONS WITH OUTDOOR ACTIVITIES
PLANNED SUNDAY MORNING...ESPECIALLY ALONG THE COAST...SHOULD AT LEAST PLAN
FOR THE VERY LOW CHANCE OF PRECIP. RAINFALL AMOUNTS WILL BE VERY LIGHT.

LONG TERM(MONDAY-THURSDAY)...
ONCE THE PRECIP ENDS SUNDAY AFTERNOON...MUCH DRIER WEATHER IS
EXPECTED FOR THE ENTIRE LONG TERM. MEDIUM RANGE MODELS STILL
INDICATE BUILDING HIGH PRESSURE AND DEVELOPING OFFSHORE FLOW BY
TUESDAY. THE OFFSHORE FLOW WILL BE STRONGEST FROM MONDAY NIGHT
THROUGH WEDNESDAY NIGHT. THE DAYTIME WILL BE MILD AND VERY DRY
WITH HIGHS IN THE 80S TO MID 90S INLAND...70S AT THE COAST.
OVERNIGHT LOWS WILL SEE THERMAL BELTS WITH MILD TEMPS IN THE HILLS
WITH MODERATE TO POOR HUMIDITY RECOVERIES. THAT BEING SAID...FIRE
WEATHER MAY BECOME MORE OF A CONCERN NEXT WEEK.

&&

.AVIATION...AS OF 5:30 PM PDT THURSDAY...APPROACHING UPPER TROUGH
IS PUSHING STRATUS INTO THE SFO BAY AREA EARLY. THIS IS SUPPORTED
BY WEB CAMERAS WHICH SHOW STRATUS ALREADY MOVING IN OVER SFO.
LOOKS LIKE THE CIGS WILL FILL IN OVER SFO IN THE NEXT HOUR OR TWO
AND STAY IN FOR THE NIGHT. LOOK FOR CIGS TO SPREAD OVER THE REST OF
THE SFO BAY AREA AND THE MRY BAY AREA EARLY THIS EVENING.
SOUTHWEST WINDS WILL DECREASE AND BECOME MORE SOUTHERLY BY DAYBREAK
AS A FRONTAL SYSTEM APPROACHES. THIS FRONT SHOULD HELP MIX OUT THE
LOW CIGS.

VICINITY OF KSFO...BECOMING MVFR CIGS. SOUTHWEST WINDS TO 15 KT
GUSTING TO 20 KT THROUGH 12Z THEN BECOMING SOUTHERLY 5-10 KT. CIGS
SHOULD RISE INTO THE VFR RANGE AS WELL.

KSFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...BECOMING MVFR BY 03-04Z.

&&

.MARINE...AS OF 02:00 PM PDT THURSDAY...WEST TO NORTHWEST WINDS WILL
PREVAIL ALONG THE CENTRAL COAST INTO THE WEEKEND. A MIXED SWELL WILL
ENTER THE SOUTHERN COASTAL WATERS ON SATURDAY FEATURING A 7 TO 9
FOOT 14 SECOND WESTERLY SWELL AND A 3 TO 4 FEET 19 TO 21 SECOND
SOUTHERLY SWELL. THE SOUTHERLY SWELL WILL PRODUCE POTENTIALLY
HAZARDOUS CONDITIONS FOR SOUTH-FACING BEACHES IN MONTEREY AND SANTA
CRUZ COUNTIES THROUGH SUNDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...SAN FRANCISCO BAY NORTH OF THE BAY BRIDGE UNTIL 8 PM
             SCA...SAN FRANCISCO BAY SOUTH OF THE BAY BRIDGE UNTIL 8 PM
             SCA...MONTEREY BAY UNTIL 8 PM
             SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 8 PM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM UNTIL 5 AM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM

&&

$$

PUBLIC FORECAST: CW
AVIATION/MARINE: W PI

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