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

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000
FXUS66 KMTR 012202
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
302 PM PDT WED JUL 1 2015

.SYNOPSIS... MONSOONAL MOISTURE AND ENERGY WILL RESULT IN
ISOLATED SHOWERS AND THUNDERSTORMS FOR THE SOUTHERN COUNTIES
THIS EVENING AND POSSIBLY OVERNIGHT. A COOLING TREND WILL
BEGIN TOMORROW AND CONTINUE INTO THE WEEKEND AS TEMPERATURES
APPROACH NORMAL VALUES.

&&

.DISCUSSION...AS OF 03:00 PM PDT WEDNESDAY... CALIFORNIA IS
BETWEEEN A 595DM DOME OF HIGH PRESSURE OVER THE GREAT BASIN AND A
581DM LOW PRESSURE SYSTEM WEST OF BAJA CALIFORNIA IN A TYPICAL
SUMMERTIME MONSOONAL PATTERN. MONSOONAL MOISTURE IS RESULTING IN
IMPRESSIVE PRECIPITAIBLE WATER VALUES OF BETWEEN 125% OF NORMAL
FOR MOST OF OUR FORECAST AREA TO OVER 200% OF NORMAL FOR PORTIONS
OF CENTRAL AND SOUTHERN CALIFORNIA. PRECIPITABLE WATER VALUES
RANGE FROM AROUND 1.1 INCHES OVER THE NORTH BAY TO 1.4 IN SOUTHERN
MONTEREY COUNTY... TO AROUND 1.8 OFF OF LOS ANGELES AND SAN DIEGO.
THE MOST EASILY IDENTIFIABLE FEATURE OF THIS ABUNDANCE OF MID TO
UPPER LEVEL MOISTURE IS THE INCREASE IN CLOUDINESS ACROSS THE
REGION. THESE CLOUDS ARE PREDOMINATELY BASED AT AROUND 15000 FT.

VISIBLE SATELLITE SHOWS A WELL DEFINED MESOLOW MOVING FROM THE
SOUTHEAST TOWARDS THE NORTHWEST AND INTO THE SOUTHERN PORTION OF
OUR CWA THIS AFTERNOON. THIS MID LEVEL FEATURE HAS INCREASED
INSTABILITY AROUND IT AND TRIGGERED THUNDERSTORMS ON THE NORTH
AND WEST FLANK OVER THE LAST 24 HOURS. SEVERAL LIGHTNING STRIKES
HAVE BEEN REPORTED ALREADY IN SOUTHERN MONTEREY AND SAN BENITO
COUNTY THIS AFTERNOON FROM THIS FEATURE. KMUX RADAR SHOWS A LIGHT
BAND OF RETURNS AROUND THE CENTER OF THI FEATURE HOWEVER MOST OF
THE PRECIPITATION IS FALLING FROM 15000 FT OR MORE AND MAY ONLY BE
RESULTING IN VIRGA. THUS FAR... ONLY A FEW HUNDRETH HAVE BEEN
REPORTED BENEATH THESE RETURNS. HAVE UPDATED THE FORECAST TO
PROPATE A SLIGHT CHANCE OF THUNDERSTORMS OVER SANTA CRUZ AND AND
SANTA CLARA COUNTY INTO THE EVENING AND POSSIBLY FURTHER NORTHWARD
INTO TONIGHT. ADDITIONAL ENERGY AND MOISTURE WILL ADVECT INTO THE
REGION OVERNIGHT TONIGHT AND... DUE TO THE ELEVATED NATURE OF THIS
CONVECTION... COULD RESULT IN A FEW NOCTURNAL FLASHES OF
LIGHTNING. SHORT TO MEDIUM TERM MODELS ARE HINTING AT THE
POSSIBILITY OF ADDITIONAL CONVECTION THURSDAY AND EVEN FRIDAY
MORNING HOWEVER UNCERTAINTY IS STILL HIGH OVER THE
TIMING/PLACEMENT.

TEMPERATURES TODAY ARE A MIXED BAG... WITH MANY LOCATIONS RUNNING
A FEW TO SEVERAL DEGREES COOLER THAN YESTERDAY AND A MUCH SMALLER
PORTION AS WARM OR EVEN WARMER TODAY. THE WARMEST AREA WAS IN AND
AROUND THE EAST AND SOUTH BAY INTERIOR... WHERE TRIPLE DIGIT
TEMPERATURES ARE ALREADY BEING OBSERVED AS OF 3PM. TEMPERATURES
ARE FORECAST TO COOL OFF SEVERAL MORE DEGREES FOR TOMORROW AND
THEN GRADUALLY COOL TOWARDS NORMAL TEMPERATURES INTO THE WEEKEND.

DRP

&&

.AVIATION...AS OF 10:50 AM PDT WEDNESDAY...MONSOONAL MOISTURE
STREAMING IN FROM THE SOUTH WILL BLANKET THE REGION WITH HIGH
CLOUDS TODAY. OTHERWISE VFR CONDITIONS WILL PREVAIL THROUGH THIS
EVENING. COASTAL LOW CLOUDS WILL PUSH BACK IN THIS EVENING
REACHING INLAND TERMINALS LATE TONIGHT. MAINLY LIGHT WEST TO
SOUTHWESTERLY FLOW WILL PREVAIL WITH A MODERATE AFTERNOON
SEABREEZE EXPECTED LATER TODAY.

VICINITY OF KSFO... VFR WITH LIGHT TO MODERATE ONSHORE FLOW.

KSFO BRIDGE APPROACH... SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR WITH LIGHT TO LOCALLY MODERATE
ONSHORE FLOW.

&&

.CLIMATE...RECORD HIGHS FOR JULY 1 FOR SELECTED LOCATIONS.

.SF BAY AREA................JULY 1
 KENTFIELD.................103/1996
 SAN RAFAEL.................99/1991
 NAPA......................103/1972
 SAN FRANCISCO..............92/1991
 SFO AIRPORT................99/1985
 OAKLAND DOWNTOWN...........92/1984
 OAKLAND AIRPORT............90/1985
 RICHMOND...................97/1985
 LIVERMORE.................110/1950
 MOUNTAIN VIEW..............97/1985
 SAN JOSE..................102/1985
 GILROY....................108/1972

MONTEREY BAY AREA............JULY 1
 MONTEREY...................96/1985
 SANTA CRUZ.................99/1970
 SALINAS....................85/1996
 SALINAS AIRPORT............88/1991
 KING CITY.................105/1985

&&

.MARINE...AS OF 02:22 PM PDT WEDNESDAY...HIGH PRESSURE ACROSS THE
COASTAL WATERS WILL MAINTAIN LIGHT WINDS AND SEAS THROUGH THE
FORECAST PERIOD. A WEAK DISTURBANCE WILL PASS BY ON THURSDAY
BRINGING SOUTHWESTERLY WINDS AND A CHANCE OF SHOWERS AND
THUNDERSTORMS TO THE REGION.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...HEAT ADVISORY...NORTH BAY AREA... EAST BAY AREA
             AND THE SANTA CLARA VALLEY.
             SCA...SF BAY UNTIL 9 PM

&&

$$

PUBLIC FORECAST: DRP
AVIATION: CW
MARINE: CW
CLIMATE: BELL


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