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

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000
FXUS66 KMTR 191740
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1040 AM PDT SUN APR 19 2015

.SYNOPSIS...COOL CONDITIONS EXPECTED TODAY ALONG THE COAST WITH A
PERSISTENT MARINE LAYER IN PLACE WHILE INLAND AREAS WARM TO ABOVE
AVERAGE VALUES. A REGION-WIDE COOLING TREND WILL TAKE PLACE EARLY
IN THE WORKWEEK AS A SERIES OF WEAK UPPER LEVEL DISTURBANCES
IMPACT THE STATE. AS A RESULT...UNSETTLED WEATHER WILL BE POSSIBLE
WITH A SLIGHT CHANCE OF SHOWERS THROUGH THE LATTER HALF OF THE
WEEK.

&&

.DISCUSSION...AS OF 8:45 AM PDT SUNDAY...WIDESPREAD CLOUDS ACROSS
OUR REGION TODAY FOR LOCATIONS UNDER 2000 FEET WHICH COINCIDES
WELL WITH THE LATEST READINGS OFF THE FORT ORD PROFILER. SURFACE
GRADIENTS ALSO SHOW A STRONGER WEST TO EAST COMPONENT COMPARED TO
YESTERDAY (UP 1 MB). STILL AM EXPECTING CLOUDS TO BURN OFF LATER
WITH MOSTLY SUNNY SKIES FOR AT LEAST PART OF THE AFTERNOON
FORECAST. HIGHS WILL RANGE FROM 60S AT THE COAST UP TO 80S WELL
INLAND.

HAVE NOT RECEIVED A COMPLETE 12Z RUN THROUGH SATURDAY YET SO WILL
BE INTERESTING TO SEE IF THERE IS ANY CHANGE IN THE OUTLOOK FOR
THIS WEEK. 12Z NAM THAT GOES OUT THROUGH WEDNESDAY HAS THE MAIN
UPPER LEVEL LOW STAYING WELL TO OUR WEST WITH ANY SHOWER ACTIVITY
LOOKING VERY SPOTTY. AGREE WITH THE PREVIOUS SHIFT THAT DRIZZLE
DOES LOOK VERY LIKELY FOR COASTAL SPOTS.

.PREVIOUS DISCUSSION...DEEPENING MARINE LAYER ACROSS THE REGION
THIS MORNING HAS RESULTED IN DECENT INLAND PENETRATION OF LOW
LEVEL CLOUDS...NOW SPREADING INTO MOST VALLEY LOCATIONS.
MEANWHILE...A WEAK MID/UPPER LEVEL LOW CAN BE SEEN ON SATELLITE
IMAGERY SPINNING OFF OF THE NORTHERN CALIFORNIA COAST. THIS
FEATURE WILL DROP SOUTHWARD TODAY AND ADVECT MID-LEVEL MOISTURE
INTO THE INTERIOR PORTIONS OF THE STATE OVER THE NEXT 12 TO 24
HOURS. ACROSS OUR REGION...MOISTURE ABOVE THE MARINE LAYER WILL BE
LIMITED AND DRY CONDITIONS WILL LIKELY PREVAIL. TEMPERATURES THIS
AFTERNOON WILL ONCE AGAIN BE COOL ALONG COASTAL LOCATIONS WHILE
INLAND AREAS AWAY FROM THE MARINE INFLUENCE WILL WARM INTO THE
UPPER 70S TO MID 80S.

SLIGHT COOLING WILL TAKE PLACE MONDAY INTO TUESDAY AS 850MB
TEMPERATURES COOL AND ONSHORE FLOW INCREASES IN RESPONSE TO
TROUGHING OFF OF THE WEST COAST. WILL MAINTAIN A DRY FORECAST ON
MONDAY WITH MODEL GUIDANCE NOW MOSTLY KEEPING PRECIPITATION OVER
THE HIGHER MOUNTAINS OF NORTHERN AND CENTRAL CALIFORNIA. WITH
THAT SAID...CANNOT RULE OUT AN ISOLATED SHOWER/THUNDERSTORM OVER
THE HIGHER TERRAIN OF SOUTHERN SAN BENITO COUNTY LATE
MONDAY...YET CONFIDENCE REMAINS LOW. WITH THE MARINE LAYER
EXPECTED TO DEEPEN FURTHER MONDAY NIGHT INTO TUESDAY...HAVE ADDED
THE MENTION OF PATCHY DRIZZLE ALONG COASTAL AREAS. BY TUESDAY
AFTERNOON/EVENING...THE MODELS SHOW SLIGHTLY BETTER INSTABILITY
AND MID-LEVEL MOISTURE OVER THE REGION TO MAINTAIN A MENTION A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS OVER THE
HILLS/MOUNTAINS. HOWEVER...MOST LOCATIONS WILL REMAIN DRY.

A SLIGHT CHANCE OF SHOWERS WILL CONTINUE WEDNESDAY AND THURSDAY
OVER THE HILLS/MOUNTAINS AS ANOTHER MID/UPPER LEVEL LOW IS
FORECAST TO DROP SOUTHWARD JUST OFF OF THE CALIFORNIA COAST.
AGAIN...WITH LIMITED MOISTURE AND LACK OF STRONG MID/UPPER LEVEL
SUPPORT...DO NOT EXPECT WIDESPREAD RAINFALL AND MEASURABLE
PRECIPITATION WILL BE ISOLATED TO SCATTERED AT BEST. AN UNSETTLED
PATTERN WILL PERSIST THROUGH LATE WEEK AND LIKELY INTO NEXT
WEEKEND WITH A SERIES OF WEAK DISTURBANCES MOVING THROUGH THE
BROAD MID/UPPER LEVEL TROUGH OVER MUCH OF THE WEST COAST.
HOWEVER...THE MODEL GUIDANCE HAS ONCE AGAIN BACKED OFF ON THE
POTENTIAL FOR WIDESPREAD PRECIPITATION THROUGH NEXT WEEKEND.

&&

.AVIATION...AS OF 10:40 AM PDT SUNDAY...MODERATELY DEEP MARINE
LAYER ALLOWED COASTAL STRATUS TO PUSH INTO INLAND VALLEYS
OVERNIGHT. SLOW CLEARING THIS MORNING BUT EXPECT VFR CONDITIONS
ALL DAY WITH EARLY RETURN TO STRATUS CONDITIONS TONIGHT. LIGHT
ONSHORE FLOW EXPECTED.

VICINITY OF KSFO...VFR THROUGH THE AFTERNOON AND EVENING. MOSTLY
LIGHT WINDS TODAY. STRATUS RETURNS TONIGHT...06-07Z.


SFO BRIDGE APPROACH...MVFR CIGS OVER THE APPROACH THROUGH 19Z.
THEN SIMILAR TO SFO.

MONTEREY BAY AREA TERMINALS...VFR. STRATUS LIKELY RETURNING EARLY
THIS EVENING...BY 02-04Z

&&

.MARINE...AS OF 10:36 AM PDT SUNDAY...A MODERATELY DEEP MARINE
LAYER WILL CONTINUE OVER THE COASTAL WATERS THROUGH EARLY WEEK.
LIGHT NORTHWEST WINDS AND GENTLE SEA CONDITIONS WILL CONTINUE
THROUGH MONDAY NIGHT. NORTHWEST WINDS ARE FORECAST TO INCREASE ON
TUESDAY AND WEDNESDAY AS LOW PRESSURE DEVELOPS OVER THE GREAT
BASIN AND HIGH PRESSURE STRENGTHENS OFFSHORE.

&&

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

$$

PUBLIC FORECAST: BELL/RGASS
AVIATION/MARINE: SIMS

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