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

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000
FXUS66 KMTR 041203
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
503 AM PDT TUE AUG 4 2015

.SYNOPSIS...SUBTROPICAL MOISTURE MOVING IN FROM THE SOUTHWEST MAY
RESULT IN ISOLATED SHOWERS AND THUNDERSTORMS ON TUESDAY...MAINLY
OVER THE SAN FRANCISCO BAY AREA...AND PARTICULARLY IN THE NORTH
BAY. OTHERWISE...MILD TEMPERATURES ARE FORECAST TO CONTINUE
THROUGH TUESDAY. A MODEST WARMING TREND IS THEN EXPECTED WEDNESDAY
AND THURSDAY AS HIGH PRESSURE BUILDS ACROSS THE REGION. COOLER
TEMPERATURES WITH ISOLATED SHOWERS AND THUNDERSTORMS MAY OCCUR
FRIDAY.

&&

.DISCUSSION...AS OF 3:30 AM PDT TUESDAY...SATELLITE IMAGE SHOWS
STRATUS IS SLOWER TO MOVE ONSHORE THIS MORNING. THE STRATUS IS
FINALLY FILLING IN OVER THE COASTAL WATERS AND IS STILL EXPECTED
TO REACH THE SFO AND MRY BAY AREA AFTER SUNRISE.

MID AND HIGH CLOUDS WILL INCREASE OVER THE SFO BAY AREA AND NORTH
BAY AS AN UPPER LEVEL DISTURBANCE APPROACHES THE NORTHERN
CALIFORNIA COAST. THIS DISTURBANCE WILL MOVE INLAND THIS
AFTERNOON WITH MODELS INDICATING WEAK INSTABILITY OVER THE NORTH
BAY AS THE SYSTEM MOVES INLAND WITH CAPE VALUES AROUND 200 J/KG.
THE COMBINATION OF THE WEAK INSTABILITY AND THE MOISTURE WILL
BRING A SLIGHT CHANCE OF SHOWERS OR THUNDERSTORMS FROM THE SFO BAY
AREA NORTH THIS AFTERNOON. TEMPERATURES WILL BE ABOUT 3-5 DEGREES
COOLER TODAY. CONVECTION THREAT WILL END TUESDAY EVENING AS THE
SYSTEM MOVES NORTHEAST. DRIER SOUTHWEST FLOW ALOFT WILL BRING
WARMER TEMPERATURES TO THE AREA WEDNESDAY AND THURSDAY. THE
STRATUS SHOULD REMAIN INTACT AND CONTINUE TO BRING NIGHT AND
MORNING LOW CLOUDS TO THE COASTAL AREAS.

ANOTHER UPPER LEVEL LOW WILL APPROACH THE STATE ON FRIDAY. MEDIUM
RANGE MODELS INDICATE THIS IS A SLIGHTLY STRONGER SYSTEM...WILL
HAVE MORE INSTABILITY THROUGH UPWARD VERTICAL MOTION...AND WILL
MOVE ACROSS OUR CWA. HAVE INTRODUCED A SLIGHT CHANCE OF CONVECTION
FROM THE SFO BAY AREA NORTH FOR FRIDAY. TEMPERATURES WILL BE
COOLER. DRY SOUTHWESTERLY FLOW RETURNS FOR NEXT WEEKEND.

&&

.AVIATION...AS OF 4:58 AM PDT TUESDAY...FOR 12Z TAFS...HIGH CLOUDS
CONTINUE TO MOVE ACROSS THE REGION THIS MORNING WITH LOW CLOUDS
GRADUALLY FILLING IN ALONG THE COAST AND DEVELOPING LOCALLY
INLAND. TEMPORARY CIGS ANTICIPATED THIS MORNING WITH AND EARLY
CLEARING EXPECTED. WINDS WILL REMAIN LIGHT THROUGH MIDDAY.
MODERATE CONFIDENCE.

VICINITY OF KSFO...TEMPORARY MVFR CIGS EXPECTED TO FORM BETWEEN
12Z-16Z THIS MORNING. LIGHT WINDS AROUND 10 KT WILL INCREASE TO
AROUND 15 KT THIS AFTERNOON.

KSFO BRIDGE APPROACH... SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WITH MAINLY HIGH
CLOUDS. TEMPORARY CIGS CAN`T BE RULED OUT AROUND SUNRISE THIS
MORNING. LOW CONFIDENCE. LIGHT WINDS.

&&

.MARINE...AS OF 2:26 AM PDT TUESDAY...PREDOMINATELY LIGHT TO
LOCALLY MODERATE WINDS AND CALM SEAS ARE FORECAST THROUGH TONIGHT.
THE STRONGEST WINDS WILL BE OVER THE NORTHERN SAN FRANCISCO BAY IN
THE AFTERNOON...ESPECIALLY NEAR THE GOLDEN GATE BRIDGE AND ANGEL
ISLAND. WINDS INCREASE AND SHIFT TO THE NORTHWEST MIDWEEK.

&&

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

$$

PUBLIC FORECAST: W PI
AVIATION: CW
MARINE: CW


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