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

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000
FXUS66 KMTR 052339
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
439 PM PDT THU MAY 5 2016

.SYNOPSIS...AN UPPER LEVEL LOW OFF OF THE CENTRAL COAST WILL
SHIFT INLAND OVER SOUTHERN CALIFORNIA AND RESULT IN ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS THROUGH SATURDAY. BY SUNDAY,
DRY WEATHER CONDITIONS ARE FORECAST TO RETURN AND PERSIST THROUGH
THE MIDDLE OF NEXT WEEK ALONG WITH A GRADUAL WARMING TREND.

&&

.DISCUSSION...AS OF 01:41 PM PDT THURSDAY...THE CENTER OF A
MID/UPPER LEVEL LOW IS CURRENTLY POSITIONED OFF OF THE CENTRAL
COAST THIS AFTERNOON. WITH THIS SYSTEM, MOISTURE CONTINUES TO
ADVECT OVER THE REGION WITH INCREASED INSTABILITY. AS A RESULT,
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS HAVE IMPACTED THE
NORTH AND EAST BAY REGIONS EARLY THIS MORNING AND CONTINUE OVER
THE NORTH BAY AT THIS HOUR. MEANWHILE, SHOWERS HAVE FINALLY
STARTED TO DEVELOP OVER THE CENTRAL COAST AND IS EXPECTED TO
INCREASE IN COVERAGE THROUGH THE AFTERNOON. ISOLATED TO SCATTERED
SHOWERS WILL PERSIST THROUGH THE EVENING AS THE MID/UPPER LEVEL
SYSTEM SLOWLY PUSHES INLAND OVER SOUTHERN CALIFORNIA THROUGH
TONIGHT. RAINFALL AMOUNTS WILL BE SPOTTY, YET CANNOT RULE OUT
BRIEF MODERATELY TO LOCALLY HEAVY RAINFALL WITH ANY SHOWERS THAT
MOVE OVER A REGION.

THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH
SATURDAY AS THE MID/UPPER LEVEL SYSTEM MOVES VERY LITTLE INLAND
THROUGH LATE WEEK. THE FORECAST MODELS DO INDICATE THE POTENTIAL FOR
A MORE ORGANIZED BAND OF PRECIPITATION WRAPPING AROUND THE UPPER
LEVEL LOW FRIDAY MORNING/AFTERNOON. HOWEVER, THE MODELS DIFFER ON
THE LOCATION OF THIS DEVELOPMENT. THUS, DO HAVE INCREASED CHANCES OF
PRECIPITATION REGION-WIDE ON FRIDAY AS A RESULT. WHILE THE THREAT
FOR THUNDERSTORMS DECREASES SLIGHTLY ON FRIDAY, THERE REMAINS A
SLIGHT CHANCE GIVEN THE COLDER, MORE UNSTABLE AIR MASS ALOFT. IN
ADDITION, TEMPERATURES WILL REMAIN ON THE COOL SIDE OF SEASONAL
AVERAGES GIVEN THE PROXIMITY OF THE UPPER LEVEL FEATURE.

SHOWER ACTIVITY WILL DIMINISH DURING THE DAY ON SATURDAY AS THE
UPPER LEVEL SYSTEM PUSHES INTO THE DESERT SOUTHWEST. BY SUNDAY, DRY
CONDITIONS ARE FORECAST TO RETURN TO THE ENTIRE REGION AS MID/UPPER
LEVEL HIGH PRESSURE BEGINS TO DEVELOP OVER THE EASTERN PACIFIC.
EARLY NEXT WEEK, THE RIDGE WILL BUILD AND SHIFT CLOSER TO THE WEST
COAST AND RESULT IN A GRADUAL WARMING TREND. AS A RESULT, EXPECT
TEMPERATURES TO REBOUND BACK TO NEAR OR SLIGHTLY ABOVE SEASONAL
AVERAGES BY THE MIDDLE OF NEXT WEEK WITH ONGOING DRY WEATHER
CONDITIONS.

&&

.AVIATION...AS OF 4:30 PM PDT THURSDAY...UPPER LEVEL LOW WEST OF
THE CENTRAL COAST AREA WITH SCATTERED SHOWERS ROTATING THROUGH
THE AREA FROM SOUTH TO NORTH. CIGS HAVE REMAINED AT OR ABOVE 3000
FEET BUT MAY LOWER INTO MVFR RANGE TONIGHT AS LOW-LEVEL COOLING
TAKES PLACE. THE LOW WILL MOVE SLOWLY INTO SOUTHERN CALIFORNIA
TONIGHT AND FRIDAY WITH WRAP-AROUND SHOWERS CONTINUING OVER THE
AREA. CANNOT RULE OUT A THUNDERSTORM DURING THE AFTERNOON HOURS.

VICINITY OF KSFO...OCCASIONAL MVFR CIGS THROUGH 04Z. BECOMING
PREDOMINATELY MVFR AFTER 04Z AS COOLING OF THE LOWER ATMOSPHERE
TAKES PLACE. RADAR INDICATES NO SHOWER ACTIVITY IN THE VICINITY
BUT SCATTERED SHOWERS MAY SPREAD INTO THE AREA FROM THE SOUTH
TONIGHT AND FROM THE EAST TO SOUTHEAST FRIDAY. SOUTHWEST WINDS
10-15 KT.

SFO BRIDGE APPROACH...SIMILAR AS KSFO.

MONTEREY BAY TERMINALS...VFR WITH CIGS REMAINING ABOVE 3000 FEET.
CIGS LOWERING TO MVFR RANGE AFTER 06Z. VCSH THROUGH THE PERIOD.

&&

.MARINE...AS OF 4:30 PM PDT THURSDAY...A STORM SYSTEM OVER THE
REGION WILL BRING MODERATE NORTHERLY WINDS TO THE OUTER WATERS
NORTH OF PT REYES AND LIGHT SOUTH WINDS ELSEWHERE INTO TOMORROW.
HAZARDOUS CONDITIONS FROM SQUARED SEAS WILL BE ALSO BE POSSIBLE IN
THE NORTHERN OUTER WATERS. THIS STORM WILL PRODUCE SHOWERS AND
POSSIBLY THUNDERSTORMS OVER THE COASTAL WATERS TODAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...PT ARENA TO PIGEON PT 10-60 NM

&&

$$

PUBLIC FORECAST: RGASS
AVIATION: W PI
MARINE: DRP


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