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000
FXUS66 KMTR 210358
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
858 PM PDT MON APR 20 2015

.SYNOPSIS...A DEEP MARINE LAYER WILL ALLOW LOW CLOUDS TO SPREAD
WELL INLAND DURING THE NIGHT AND MORNING HOURS...KEEPING
TEMPERATURES SLIGHTLY BELOW NORMAL INTO TUESDAY. ALTHOUGH
TEMPERATURES ARE EXPECTED TO WARM SLIGHTLY BY WEDNESDAY...UPPER
LEVEL DISTURBANCES WILL KEEP TEMPERATURES NEAR TO SLIGHTLY BELOW
NORMAL THROUGH THE END OF THE WORK WEEK. THERE WILL ALSO BE A
SLIGHT CHANCE OF SHOWERS AT TIMES THIS WEEK...PRIMARILY OVER THE
HIGHER HILLS.

&&

.DISCUSSION...AS OF 8:55 PM PDT MONDAY...A RELATIVELY DEEP MARINE
LAYER ALONG WITH INCREASING ONSHORE FLOW ALLOWED MARINE AIR TO
SURGE WELL INLAND LAST NIGHT AND TODAY. AS A RESULT...COOLING
OCCURRED ACROSS NEARLY OUR ENTIRE FORECAST AREA TODAY...AND
AFTERNOON HIGHS WERE SLIGHTLY BELOW NORMAL AT MOST LOCATIONS.

A WEAK UPPER LOW OFF THE SOUTHERN CA COAST WILL MOVE EASTWARD
OVERNIGHT AND INLAND OVER SOUTHERN CA ON TUESDAY. MEANWHILE...A
TROUGH DROPPING SE OUT OF THE GULF OF ALASKA WILL APPROACH
NORTHERN CA ON TUESDAY. THESE WEATHER SYSTEMS WILL LIKELY GENERATE
SUFFICIENT INSTABILITY FOR SHOWERS/THUNDERSTORMS ACROSS PORTIONS OF
CA ON TUESDAY...BUT ONLY OVER THE HIGHER MOUNTAINS SUCH AS THE
SIERRA NEVADA AND MOUNTAINS OF FAR NORTHERN CA. OUR FORECAST AREA
WILL ALMOST CERTAINLY REMAIN DRY...EXCEPT FOR AN OUTSIDE CHANCE OF
CONVECTION OVER SOUTHERN MONTEREY AND SAN BENITO COUNTIES. THE
TROUGH APPROACHING FROM THE NW WILL ENHANCE ONSHORE FLOW AND
PERHAPS DEEPEN THE MARINE LAYER FURTHER. THIS MAY RESULT IN AREAS
OF DRIZZLE TONIGHT/TUESDAY MORNING AND AGAIN ON TUESDAY
NIGHT...ESPECIALLY IN COASTAL AREAS.

THE TROUGH COMING IN FROM THE NORTHWEST TOMORROW WILL BRING WITH
IT A COOLER AIRMASS WHICH SHOULD HELP DISRUPT THE MARINE LAYER AND
BREAK UP THE PERSISTENT COASTAL LOW CLOUDS BY WEDNESDAY AFTERNOON.
TEMPERATURES TOMORROW ARE EXPECTED TO BE NEAR PERSISTENCE...OR
PERHAPS A FEW DEGREES COOLER THAN TODAY. BUT WITH MORE AFTERNOON
SUN EXPECTED ON WEDNESDAY...TEMPERATURES SHOULD WARM A
BIT...ESPECIALLY IN COASTAL AREAS.

THE MODELS AGREE IN KEEPING A TROUGH OVER CA THROUGH THE END OF
THE WORK WEEK...AND ALSO AGREE THAT CONVECTIVE PRECIPITATION WILL
CONTINUE ACROSS PORTIONS OF CA...BUT MAINLY OVER THE HIGHER
MOUNTAINS. SHOWER CHANCES IN OUR AREA REMAIN SLIGHT AT BEST.

FROM PREVIOUS DISCUSSION...THE LONG RANGE MODELS HAVE BACKED OFF
ON ANY APPRECIABLE RAIN CHANCES FOR OUR CWA. THE 12Z ECMWF NOW
BUILDS A RIDGE OVER THE BAY AREA THIS WEEKEND AS AN INSIDE SLIDER
DIVES INTO NEVADA ON SATURDAY MORNING. SO IF ANYTHING THE TREND
FOR THE WEEKEND LOOKS WARMER WITH INCREASED COASTAL SUNSHINE.

GIVEN THE TRENDS ON ECMWF/CMC AND GFS MODELS HAVE PULLED POPS FROM
THE LONG RANGE FORECAST THAT PREVIOUSLY INCLUDED SLIGHT CHANCE OF
RAIN FOR THE NORTH BAY.

&&

.AVIATION...AS OF 5:00 PM PDT MONDAY...MAINLY CLEAR SKIES PREVAIL
OVER MOST TERMINALS WITH THE EXCEPTION OF KMTR AND KSNS. STRATUS
WILL MAKE AN EARLY RETURN TONIGHT WITH LOW CLOUDS EXPECTED TO
PUSH INLAND AROUND 03Z-04Z THIS EVENING. BORDERLINE IFR/MVFR CIGS
EXPECTED. ONSHORE WINDS WILL BE GUSTY ALONG THE EDGES OF THE
STRATUS FIELD AS WELL AS THROUGH AREAS WHERE THE WIND IS FUNNELED
THROUGH COASTAL GAPS. SPEEDS SHOULD CONTINUE AROUND 10 TO 15 KT
WITH GUSTS AROUND 20 KT THROUGH THIS EVENING BEFORE EASING AND
BECOMING LIGHT OVERNIGHT. A SIMILAR CLEARING TIME IS EXPECTED
TUESDAY MORNING AROUND 19Z-20Z. MODERATELY HIGH CONFIDENCE.

VICINITY OF KSFO...VFR CIGS WILL TRANSITIONS TO BORDERLINE
IFR/MVFR CIGS AROUND 03Z-04Z THIS EVENING. UNTIL THEN...MODERATE
WEST WINDS AROUND 15 KT WITH OCCASIONALLY GUSTS TO AROUND 20 KT ARE
EXPECTED. WINDS WILL EASE TO 10 KT OR LESS OVERNIGHT. CLEARING IS
ANTICIPATED AROUND 20Z TUESDAY MORNING. MODERATELY HIGH CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...MVFR CIGS WILL LOWER TO VFR EARLY
THIS EVENING. WEST TO SOUTHWEST WINDS AROUND 10 KT EXPECTED
THROUGH THE EVENING WITH LIGHTER WINDS ANTICIPATED OVERNIGHT. CIGS
WILL LIFT TO MVFR AROUND 19Z-20Z TUESDAY MORNING BUT ARE NOT
FORECAST TO CLEAR.

&&

.MARINE...AS OF 2:18 PM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS  HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE  FOR ZONES NORTH OF POINT
REYES WITH GALE FORCE WINDS EXPECTED IN THE  OUTER ZONE BY LATE
TUESDAY AFTERNOON. IN ADDITION...SHORT PERIOD NORTHWESTERLY SWELL
WILL GREATLY BUILD FOR THE NORTHERN OUTER ZONES ALSO BY TUESDAY
NIGHT.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM FROM 3 AM
             SCA...SF BAY NORTH OF THE BAY BRIDGE UNTIL 3 AM

&&

$$

PUBLIC FORECAST: DYKEMA/RWW
AVIATION: CW
MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
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000
FXUS66 KMTR 210358
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
858 PM PDT MON APR 20 2015

.SYNOPSIS...A DEEP MARINE LAYER WILL ALLOW LOW CLOUDS TO SPREAD
WELL INLAND DURING THE NIGHT AND MORNING HOURS...KEEPING
TEMPERATURES SLIGHTLY BELOW NORMAL INTO TUESDAY. ALTHOUGH
TEMPERATURES ARE EXPECTED TO WARM SLIGHTLY BY WEDNESDAY...UPPER
LEVEL DISTURBANCES WILL KEEP TEMPERATURES NEAR TO SLIGHTLY BELOW
NORMAL THROUGH THE END OF THE WORK WEEK. THERE WILL ALSO BE A
SLIGHT CHANCE OF SHOWERS AT TIMES THIS WEEK...PRIMARILY OVER THE
HIGHER HILLS.

&&

.DISCUSSION...AS OF 8:55 PM PDT MONDAY...A RELATIVELY DEEP MARINE
LAYER ALONG WITH INCREASING ONSHORE FLOW ALLOWED MARINE AIR TO
SURGE WELL INLAND LAST NIGHT AND TODAY. AS A RESULT...COOLING
OCCURRED ACROSS NEARLY OUR ENTIRE FORECAST AREA TODAY...AND
AFTERNOON HIGHS WERE SLIGHTLY BELOW NORMAL AT MOST LOCATIONS.

A WEAK UPPER LOW OFF THE SOUTHERN CA COAST WILL MOVE EASTWARD
OVERNIGHT AND INLAND OVER SOUTHERN CA ON TUESDAY. MEANWHILE...A
TROUGH DROPPING SE OUT OF THE GULF OF ALASKA WILL APPROACH
NORTHERN CA ON TUESDAY. THESE WEATHER SYSTEMS WILL LIKELY GENERATE
SUFFICIENT INSTABILITY FOR SHOWERS/THUNDERSTORMS ACROSS PORTIONS OF
CA ON TUESDAY...BUT ONLY OVER THE HIGHER MOUNTAINS SUCH AS THE
SIERRA NEVADA AND MOUNTAINS OF FAR NORTHERN CA. OUR FORECAST AREA
WILL ALMOST CERTAINLY REMAIN DRY...EXCEPT FOR AN OUTSIDE CHANCE OF
CONVECTION OVER SOUTHERN MONTEREY AND SAN BENITO COUNTIES. THE
TROUGH APPROACHING FROM THE NW WILL ENHANCE ONSHORE FLOW AND
PERHAPS DEEPEN THE MARINE LAYER FURTHER. THIS MAY RESULT IN AREAS
OF DRIZZLE TONIGHT/TUESDAY MORNING AND AGAIN ON TUESDAY
NIGHT...ESPECIALLY IN COASTAL AREAS.

THE TROUGH COMING IN FROM THE NORTHWEST TOMORROW WILL BRING WITH
IT A COOLER AIRMASS WHICH SHOULD HELP DISRUPT THE MARINE LAYER AND
BREAK UP THE PERSISTENT COASTAL LOW CLOUDS BY WEDNESDAY AFTERNOON.
TEMPERATURES TOMORROW ARE EXPECTED TO BE NEAR PERSISTENCE...OR
PERHAPS A FEW DEGREES COOLER THAN TODAY. BUT WITH MORE AFTERNOON
SUN EXPECTED ON WEDNESDAY...TEMPERATURES SHOULD WARM A
BIT...ESPECIALLY IN COASTAL AREAS.

THE MODELS AGREE IN KEEPING A TROUGH OVER CA THROUGH THE END OF
THE WORK WEEK...AND ALSO AGREE THAT CONVECTIVE PRECIPITATION WILL
CONTINUE ACROSS PORTIONS OF CA...BUT MAINLY OVER THE HIGHER
MOUNTAINS. SHOWER CHANCES IN OUR AREA REMAIN SLIGHT AT BEST.

FROM PREVIOUS DISCUSSION...THE LONG RANGE MODELS HAVE BACKED OFF
ON ANY APPRECIABLE RAIN CHANCES FOR OUR CWA. THE 12Z ECMWF NOW
BUILDS A RIDGE OVER THE BAY AREA THIS WEEKEND AS AN INSIDE SLIDER
DIVES INTO NEVADA ON SATURDAY MORNING. SO IF ANYTHING THE TREND
FOR THE WEEKEND LOOKS WARMER WITH INCREASED COASTAL SUNSHINE.

GIVEN THE TRENDS ON ECMWF/CMC AND GFS MODELS HAVE PULLED POPS FROM
THE LONG RANGE FORECAST THAT PREVIOUSLY INCLUDED SLIGHT CHANCE OF
RAIN FOR THE NORTH BAY.

&&

.AVIATION...AS OF 5:00 PM PDT MONDAY...MAINLY CLEAR SKIES PREVAIL
OVER MOST TERMINALS WITH THE EXCEPTION OF KMTR AND KSNS. STRATUS
WILL MAKE AN EARLY RETURN TONIGHT WITH LOW CLOUDS EXPECTED TO
PUSH INLAND AROUND 03Z-04Z THIS EVENING. BORDERLINE IFR/MVFR CIGS
EXPECTED. ONSHORE WINDS WILL BE GUSTY ALONG THE EDGES OF THE
STRATUS FIELD AS WELL AS THROUGH AREAS WHERE THE WIND IS FUNNELED
THROUGH COASTAL GAPS. SPEEDS SHOULD CONTINUE AROUND 10 TO 15 KT
WITH GUSTS AROUND 20 KT THROUGH THIS EVENING BEFORE EASING AND
BECOMING LIGHT OVERNIGHT. A SIMILAR CLEARING TIME IS EXPECTED
TUESDAY MORNING AROUND 19Z-20Z. MODERATELY HIGH CONFIDENCE.

VICINITY OF KSFO...VFR CIGS WILL TRANSITIONS TO BORDERLINE
IFR/MVFR CIGS AROUND 03Z-04Z THIS EVENING. UNTIL THEN...MODERATE
WEST WINDS AROUND 15 KT WITH OCCASIONALLY GUSTS TO AROUND 20 KT ARE
EXPECTED. WINDS WILL EASE TO 10 KT OR LESS OVERNIGHT. CLEARING IS
ANTICIPATED AROUND 20Z TUESDAY MORNING. MODERATELY HIGH CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...MVFR CIGS WILL LOWER TO VFR EARLY
THIS EVENING. WEST TO SOUTHWEST WINDS AROUND 10 KT EXPECTED
THROUGH THE EVENING WITH LIGHTER WINDS ANTICIPATED OVERNIGHT. CIGS
WILL LIFT TO MVFR AROUND 19Z-20Z TUESDAY MORNING BUT ARE NOT
FORECAST TO CLEAR.

&&

.MARINE...AS OF 2:18 PM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS  HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE  FOR ZONES NORTH OF POINT
REYES WITH GALE FORCE WINDS EXPECTED IN THE  OUTER ZONE BY LATE
TUESDAY AFTERNOON. IN ADDITION...SHORT PERIOD NORTHWESTERLY SWELL
WILL GREATLY BUILD FOR THE NORTHERN OUTER ZONES ALSO BY TUESDAY
NIGHT.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM FROM 3 AM
             SCA...SF BAY NORTH OF THE BAY BRIDGE UNTIL 3 AM

&&

$$

PUBLIC FORECAST: DYKEMA/RWW
AVIATION: CW
MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 210018
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
518 PM PDT MON APR 20 2015

.SYNOPSIS...A DEEP MARINE LAYER WILL ALLOW LOW CLOUDS TO SPREAD
WELL INLAND DURING THE NIGHT AND MORNING HOURS ACROSS THE BAY AREA
THE NEXT FEW DAYS KEEPING TEMPERATURES NEAR OR SLIGHTLY BELOW
NORMAL. AN UPPER LOW OVER THE REGION MAY GENERATE SOME NIGHT AND
MORNING DRIZZLE ALONG WITH SOME AFTERNOON CUMULUS BUILD-UPS OVER
THE REMOTE INTERIOR HILLS THE COULD LEAD TO AN OUTSIDE CHANCE OF A
STRAY SHOWER OR ISOLATED THUNDERSTORM.

&&

.DISCUSSION...AS OF 2:58 PM PDT MONDAY...DEEP 2500 FOOT MARINE
LAYER IN PLACE WITH SFO-SAC ONSHORE FLOW CURRENTLY 2.8 MB KEEPING
ONSHORE WINDS STRONG THROUGH THE DELTA. TEMPERATURES IN THE CITY
AND HERE AT THE OFFICE IN MONTEREY CURRENTLY A COOL 57 AS OF 2 PM
WITH LIVERMORE ONLY 71 WITH A 15 MPH WEST WIND. CONVECTION HAS
FIRED ACROSS MOST OF THE HIGHER MOUNTAINS ACROSS THE STATE WITH
DEBRIS CLOUDS OFF THE SIERRA CURRENTLY ROTATING IN AN EAST TO WEST
DIRECTION DUE TO THE CIRCULATION OF LOW PRESSURE OVER SOUTHERN
CALIFORNIA AND A WEAK UPPER HIGH OVER OREGON. NOT OUT OF THE
QUESTION THAT A FEW HIGH LEVEL DEBRIS CLOUDS COULD DRIFT OVER THE
EAST BAY BY LATER THIS EVENING. SO FAR ONLY SOME CUMULUS CLOUDS
HAVE DEVELOPED OVER THE HIGHEST INTERIOR HILLS OF SAN BENITO
COUNTY THIS AFTERNOON WHICH MODELS HAVE HANDLED FAIRLY WELL.

LOOKING AHEAD...EXPECT THE MARINE LAYER TO STAY AT LEAST 2500 FEET
DEEP TONIGHT AND MAY EVEN APPROACH 3000 FEET ALLOWING FOR ANOTHER
DEEP INLAND PUSH OF MARINE CLOUDS BY TUESDAY MORNING. IN GENERAL
JUST GOING WITH A PERSISTENCE FORECAST IN TERMS OF TEMPERATURE ON TUESDAY.

IN GENERAL THE MODELS HAVE KEPT BACKING OFF ON ANY SHOWER CHANCES
FOR OUR CWA THE NEXT SEVERAL DAYS AS AN UPPER LEVEL TROUGH
APPROACHES WHILE AFTERNOON CONVECTION LOOKS TO OCCUR EACH DAY OVER
THE SIERRA AND NORTHERN MOUNTAINS. HAVE MAINTAINED SOME VERY LOW
AFTERNOON SHOWER/T-STORM CHANCES OVER THE HIGHER TERRAIN OF SAN
BENITO COUNTY AND ALONG THE NAPA/LAKE COUNTY BORDER. HOWEVER FOR
THE MAJORITY OF FOLKS THE MAIN WEATHER THEME WILL BE A MORE
TYPICAL NIGHT AND MORNING LOW CLOUD DECK CLEARING BACK TO THE
COAST TYPE OF FORECAST.

UNFORTUNATELY THE LONG RANGE MODELS HAVE BACKED OFF ON ANY
APPRECIABLE RAIN CHANCES FOR OUR CWA. THE 12Z ECMWF NOW BUILDS A
RIDGE OVER THE BAY AREA THIS WEEKEND AS AN INSIDE SLIDER DIVES
INTO NEVADA ON SATURDAY MORNING. SO IF ANYTHING THE TREND FOR THE
WEEKEND LOOKS WARMER WITH INCREASED COASTAL SUNSHINE.

GIVEN THE TRENDS ON ECMWF/CMC AND GFS MODELS HAVE PULLED POPS FROM
THE LONG RANGE FORECAST THAT PREVIOUSLY INCLUDED SLIGHT CHANCE OF
RAIN FOR THE NORTH BAY.

&&

.AVIATION...AS OF 5:00 PM PDT MONDAY...MAINLY CLEAR SKIES PREVAIL
OVER MOST TERMINALS WITH THE EXCEPTION OF KMTR AND KSNS. STRATUS
WILL MAKE AN EARLY RETURN TONIGHT WITH LOW CLOUDS EXPECTED TO
PUSH INLAND AROUND 03Z-04Z THIS EVENING. BORDERLINE IFR/MVFR CIGS
EXPECTED. ONSHORE WINDS WILL BE GUSTY ALONG THE EDGES OF THE
STRATUS FIELD AS WELL AS THROUGH AREAS WHERE THE WIND IS FUNNELED
THROUGH COASTAL GAPS. SPEEDS SHOULD CONTINUE AROUND 10 TO 15 KT
WITH GUSTS AROUND 20 KT THROUGH THIS EVENING BEFORE EASING AND
BECOMING LIGHT OVERNIGHT. A SIMILAR CLEARING TIME IS EXPECTED
TUESDAY MORNING AROUND 19Z-20Z. MODERATELY HIGH CONFIDENCE.

VICINITY OF KSFO...VFR CIGS WILL TRANSITIONS TO BORDERLINE
IFR/MVFR CIGS AROUND 03Z-04Z THIS EVENING. UNTIL THEN...MODERATE
WEST WINDS AROUND 15 KT WITH OCCASIONALLY GUSTS TO AROUND 20 KT ARE
EXPECTED. WINDS WILL EASE TO 10 KT OR LESS OVERNIGHT. CLEARING IS
ANTICIPATED AROUND 20Z TUESDAY MORNING. MODERATELY HIGH CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...MVFR CIGS WILL LOWER TO VFR EARLY
THIS EVENING. WEST TO SOUTHWEST WINDS AROUND 10 KT EXPECTED
THROUGH THE EVENING WITH LIGHTER WINDS ANTICIPATED OVERNIGHT. CIGS
WILL LIFT TO MVFR AROUND 19Z-20Z TUESDAY MORNING BUT ARE NOT
FORECAST TO CLEAR.

&&

.MARINE...AS OF 2:18 PM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS  HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE  FOR ZONES NORTH OF POINT
REYES WITH GALE FORCE WINDS EXPECTED IN THE  OUTER ZONE BY LATE
TUESDAY AFTERNOON. IN ADDITION...SHORT PERIOD NORTHWESTERLY SWELL
WILL GREATLY BUILD FOR THE NORTHERN OUTER ZONES ALSO BY TUESDAY
NIGHT.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM FROM 3 AM
             SCA...SF BAY NORTH OF THE BAY BRIDGE UNTIL 3 AM

&&

$$

PUBLIC FORECAST: RWW
AVIATION: CW
MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 210018
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
518 PM PDT MON APR 20 2015

.SYNOPSIS...A DEEP MARINE LAYER WILL ALLOW LOW CLOUDS TO SPREAD
WELL INLAND DURING THE NIGHT AND MORNING HOURS ACROSS THE BAY AREA
THE NEXT FEW DAYS KEEPING TEMPERATURES NEAR OR SLIGHTLY BELOW
NORMAL. AN UPPER LOW OVER THE REGION MAY GENERATE SOME NIGHT AND
MORNING DRIZZLE ALONG WITH SOME AFTERNOON CUMULUS BUILD-UPS OVER
THE REMOTE INTERIOR HILLS THE COULD LEAD TO AN OUTSIDE CHANCE OF A
STRAY SHOWER OR ISOLATED THUNDERSTORM.

&&

.DISCUSSION...AS OF 2:58 PM PDT MONDAY...DEEP 2500 FOOT MARINE
LAYER IN PLACE WITH SFO-SAC ONSHORE FLOW CURRENTLY 2.8 MB KEEPING
ONSHORE WINDS STRONG THROUGH THE DELTA. TEMPERATURES IN THE CITY
AND HERE AT THE OFFICE IN MONTEREY CURRENTLY A COOL 57 AS OF 2 PM
WITH LIVERMORE ONLY 71 WITH A 15 MPH WEST WIND. CONVECTION HAS
FIRED ACROSS MOST OF THE HIGHER MOUNTAINS ACROSS THE STATE WITH
DEBRIS CLOUDS OFF THE SIERRA CURRENTLY ROTATING IN AN EAST TO WEST
DIRECTION DUE TO THE CIRCULATION OF LOW PRESSURE OVER SOUTHERN
CALIFORNIA AND A WEAK UPPER HIGH OVER OREGON. NOT OUT OF THE
QUESTION THAT A FEW HIGH LEVEL DEBRIS CLOUDS COULD DRIFT OVER THE
EAST BAY BY LATER THIS EVENING. SO FAR ONLY SOME CUMULUS CLOUDS
HAVE DEVELOPED OVER THE HIGHEST INTERIOR HILLS OF SAN BENITO
COUNTY THIS AFTERNOON WHICH MODELS HAVE HANDLED FAIRLY WELL.

LOOKING AHEAD...EXPECT THE MARINE LAYER TO STAY AT LEAST 2500 FEET
DEEP TONIGHT AND MAY EVEN APPROACH 3000 FEET ALLOWING FOR ANOTHER
DEEP INLAND PUSH OF MARINE CLOUDS BY TUESDAY MORNING. IN GENERAL
JUST GOING WITH A PERSISTENCE FORECAST IN TERMS OF TEMPERATURE ON TUESDAY.

IN GENERAL THE MODELS HAVE KEPT BACKING OFF ON ANY SHOWER CHANCES
FOR OUR CWA THE NEXT SEVERAL DAYS AS AN UPPER LEVEL TROUGH
APPROACHES WHILE AFTERNOON CONVECTION LOOKS TO OCCUR EACH DAY OVER
THE SIERRA AND NORTHERN MOUNTAINS. HAVE MAINTAINED SOME VERY LOW
AFTERNOON SHOWER/T-STORM CHANCES OVER THE HIGHER TERRAIN OF SAN
BENITO COUNTY AND ALONG THE NAPA/LAKE COUNTY BORDER. HOWEVER FOR
THE MAJORITY OF FOLKS THE MAIN WEATHER THEME WILL BE A MORE
TYPICAL NIGHT AND MORNING LOW CLOUD DECK CLEARING BACK TO THE
COAST TYPE OF FORECAST.

UNFORTUNATELY THE LONG RANGE MODELS HAVE BACKED OFF ON ANY
APPRECIABLE RAIN CHANCES FOR OUR CWA. THE 12Z ECMWF NOW BUILDS A
RIDGE OVER THE BAY AREA THIS WEEKEND AS AN INSIDE SLIDER DIVES
INTO NEVADA ON SATURDAY MORNING. SO IF ANYTHING THE TREND FOR THE
WEEKEND LOOKS WARMER WITH INCREASED COASTAL SUNSHINE.

GIVEN THE TRENDS ON ECMWF/CMC AND GFS MODELS HAVE PULLED POPS FROM
THE LONG RANGE FORECAST THAT PREVIOUSLY INCLUDED SLIGHT CHANCE OF
RAIN FOR THE NORTH BAY.

&&

.AVIATION...AS OF 5:00 PM PDT MONDAY...MAINLY CLEAR SKIES PREVAIL
OVER MOST TERMINALS WITH THE EXCEPTION OF KMTR AND KSNS. STRATUS
WILL MAKE AN EARLY RETURN TONIGHT WITH LOW CLOUDS EXPECTED TO
PUSH INLAND AROUND 03Z-04Z THIS EVENING. BORDERLINE IFR/MVFR CIGS
EXPECTED. ONSHORE WINDS WILL BE GUSTY ALONG THE EDGES OF THE
STRATUS FIELD AS WELL AS THROUGH AREAS WHERE THE WIND IS FUNNELED
THROUGH COASTAL GAPS. SPEEDS SHOULD CONTINUE AROUND 10 TO 15 KT
WITH GUSTS AROUND 20 KT THROUGH THIS EVENING BEFORE EASING AND
BECOMING LIGHT OVERNIGHT. A SIMILAR CLEARING TIME IS EXPECTED
TUESDAY MORNING AROUND 19Z-20Z. MODERATELY HIGH CONFIDENCE.

VICINITY OF KSFO...VFR CIGS WILL TRANSITIONS TO BORDERLINE
IFR/MVFR CIGS AROUND 03Z-04Z THIS EVENING. UNTIL THEN...MODERATE
WEST WINDS AROUND 15 KT WITH OCCASIONALLY GUSTS TO AROUND 20 KT ARE
EXPECTED. WINDS WILL EASE TO 10 KT OR LESS OVERNIGHT. CLEARING IS
ANTICIPATED AROUND 20Z TUESDAY MORNING. MODERATELY HIGH CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...MVFR CIGS WILL LOWER TO VFR EARLY
THIS EVENING. WEST TO SOUTHWEST WINDS AROUND 10 KT EXPECTED
THROUGH THE EVENING WITH LIGHTER WINDS ANTICIPATED OVERNIGHT. CIGS
WILL LIFT TO MVFR AROUND 19Z-20Z TUESDAY MORNING BUT ARE NOT
FORECAST TO CLEAR.

&&

.MARINE...AS OF 2:18 PM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS  HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE  FOR ZONES NORTH OF POINT
REYES WITH GALE FORCE WINDS EXPECTED IN THE  OUTER ZONE BY LATE
TUESDAY AFTERNOON. IN ADDITION...SHORT PERIOD NORTHWESTERLY SWELL
WILL GREATLY BUILD FOR THE NORTHERN OUTER ZONES ALSO BY TUESDAY
NIGHT.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM FROM 3 AM
             SCA...SF BAY NORTH OF THE BAY BRIDGE UNTIL 3 AM

&&

$$

PUBLIC FORECAST: RWW
AVIATION: CW
MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 210018
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
518 PM PDT MON APR 20 2015

.SYNOPSIS...A DEEP MARINE LAYER WILL ALLOW LOW CLOUDS TO SPREAD
WELL INLAND DURING THE NIGHT AND MORNING HOURS ACROSS THE BAY AREA
THE NEXT FEW DAYS KEEPING TEMPERATURES NEAR OR SLIGHTLY BELOW
NORMAL. AN UPPER LOW OVER THE REGION MAY GENERATE SOME NIGHT AND
MORNING DRIZZLE ALONG WITH SOME AFTERNOON CUMULUS BUILD-UPS OVER
THE REMOTE INTERIOR HILLS THE COULD LEAD TO AN OUTSIDE CHANCE OF A
STRAY SHOWER OR ISOLATED THUNDERSTORM.

&&

.DISCUSSION...AS OF 2:58 PM PDT MONDAY...DEEP 2500 FOOT MARINE
LAYER IN PLACE WITH SFO-SAC ONSHORE FLOW CURRENTLY 2.8 MB KEEPING
ONSHORE WINDS STRONG THROUGH THE DELTA. TEMPERATURES IN THE CITY
AND HERE AT THE OFFICE IN MONTEREY CURRENTLY A COOL 57 AS OF 2 PM
WITH LIVERMORE ONLY 71 WITH A 15 MPH WEST WIND. CONVECTION HAS
FIRED ACROSS MOST OF THE HIGHER MOUNTAINS ACROSS THE STATE WITH
DEBRIS CLOUDS OFF THE SIERRA CURRENTLY ROTATING IN AN EAST TO WEST
DIRECTION DUE TO THE CIRCULATION OF LOW PRESSURE OVER SOUTHERN
CALIFORNIA AND A WEAK UPPER HIGH OVER OREGON. NOT OUT OF THE
QUESTION THAT A FEW HIGH LEVEL DEBRIS CLOUDS COULD DRIFT OVER THE
EAST BAY BY LATER THIS EVENING. SO FAR ONLY SOME CUMULUS CLOUDS
HAVE DEVELOPED OVER THE HIGHEST INTERIOR HILLS OF SAN BENITO
COUNTY THIS AFTERNOON WHICH MODELS HAVE HANDLED FAIRLY WELL.

LOOKING AHEAD...EXPECT THE MARINE LAYER TO STAY AT LEAST 2500 FEET
DEEP TONIGHT AND MAY EVEN APPROACH 3000 FEET ALLOWING FOR ANOTHER
DEEP INLAND PUSH OF MARINE CLOUDS BY TUESDAY MORNING. IN GENERAL
JUST GOING WITH A PERSISTENCE FORECAST IN TERMS OF TEMPERATURE ON TUESDAY.

IN GENERAL THE MODELS HAVE KEPT BACKING OFF ON ANY SHOWER CHANCES
FOR OUR CWA THE NEXT SEVERAL DAYS AS AN UPPER LEVEL TROUGH
APPROACHES WHILE AFTERNOON CONVECTION LOOKS TO OCCUR EACH DAY OVER
THE SIERRA AND NORTHERN MOUNTAINS. HAVE MAINTAINED SOME VERY LOW
AFTERNOON SHOWER/T-STORM CHANCES OVER THE HIGHER TERRAIN OF SAN
BENITO COUNTY AND ALONG THE NAPA/LAKE COUNTY BORDER. HOWEVER FOR
THE MAJORITY OF FOLKS THE MAIN WEATHER THEME WILL BE A MORE
TYPICAL NIGHT AND MORNING LOW CLOUD DECK CLEARING BACK TO THE
COAST TYPE OF FORECAST.

UNFORTUNATELY THE LONG RANGE MODELS HAVE BACKED OFF ON ANY
APPRECIABLE RAIN CHANCES FOR OUR CWA. THE 12Z ECMWF NOW BUILDS A
RIDGE OVER THE BAY AREA THIS WEEKEND AS AN INSIDE SLIDER DIVES
INTO NEVADA ON SATURDAY MORNING. SO IF ANYTHING THE TREND FOR THE
WEEKEND LOOKS WARMER WITH INCREASED COASTAL SUNSHINE.

GIVEN THE TRENDS ON ECMWF/CMC AND GFS MODELS HAVE PULLED POPS FROM
THE LONG RANGE FORECAST THAT PREVIOUSLY INCLUDED SLIGHT CHANCE OF
RAIN FOR THE NORTH BAY.

&&

.AVIATION...AS OF 5:00 PM PDT MONDAY...MAINLY CLEAR SKIES PREVAIL
OVER MOST TERMINALS WITH THE EXCEPTION OF KMTR AND KSNS. STRATUS
WILL MAKE AN EARLY RETURN TONIGHT WITH LOW CLOUDS EXPECTED TO
PUSH INLAND AROUND 03Z-04Z THIS EVENING. BORDERLINE IFR/MVFR CIGS
EXPECTED. ONSHORE WINDS WILL BE GUSTY ALONG THE EDGES OF THE
STRATUS FIELD AS WELL AS THROUGH AREAS WHERE THE WIND IS FUNNELED
THROUGH COASTAL GAPS. SPEEDS SHOULD CONTINUE AROUND 10 TO 15 KT
WITH GUSTS AROUND 20 KT THROUGH THIS EVENING BEFORE EASING AND
BECOMING LIGHT OVERNIGHT. A SIMILAR CLEARING TIME IS EXPECTED
TUESDAY MORNING AROUND 19Z-20Z. MODERATELY HIGH CONFIDENCE.

VICINITY OF KSFO...VFR CIGS WILL TRANSITIONS TO BORDERLINE
IFR/MVFR CIGS AROUND 03Z-04Z THIS EVENING. UNTIL THEN...MODERATE
WEST WINDS AROUND 15 KT WITH OCCASIONALLY GUSTS TO AROUND 20 KT ARE
EXPECTED. WINDS WILL EASE TO 10 KT OR LESS OVERNIGHT. CLEARING IS
ANTICIPATED AROUND 20Z TUESDAY MORNING. MODERATELY HIGH CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...MVFR CIGS WILL LOWER TO VFR EARLY
THIS EVENING. WEST TO SOUTHWEST WINDS AROUND 10 KT EXPECTED
THROUGH THE EVENING WITH LIGHTER WINDS ANTICIPATED OVERNIGHT. CIGS
WILL LIFT TO MVFR AROUND 19Z-20Z TUESDAY MORNING BUT ARE NOT
FORECAST TO CLEAR.

&&

.MARINE...AS OF 2:18 PM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS  HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE  FOR ZONES NORTH OF POINT
REYES WITH GALE FORCE WINDS EXPECTED IN THE  OUTER ZONE BY LATE
TUESDAY AFTERNOON. IN ADDITION...SHORT PERIOD NORTHWESTERLY SWELL
WILL GREATLY BUILD FOR THE NORTHERN OUTER ZONES ALSO BY TUESDAY
NIGHT.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM FROM 3 AM
             SCA...SF BAY NORTH OF THE BAY BRIDGE UNTIL 3 AM

&&

$$

PUBLIC FORECAST: RWW
AVIATION: CW
MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 210018
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
518 PM PDT MON APR 20 2015

.SYNOPSIS...A DEEP MARINE LAYER WILL ALLOW LOW CLOUDS TO SPREAD
WELL INLAND DURING THE NIGHT AND MORNING HOURS ACROSS THE BAY AREA
THE NEXT FEW DAYS KEEPING TEMPERATURES NEAR OR SLIGHTLY BELOW
NORMAL. AN UPPER LOW OVER THE REGION MAY GENERATE SOME NIGHT AND
MORNING DRIZZLE ALONG WITH SOME AFTERNOON CUMULUS BUILD-UPS OVER
THE REMOTE INTERIOR HILLS THE COULD LEAD TO AN OUTSIDE CHANCE OF A
STRAY SHOWER OR ISOLATED THUNDERSTORM.

&&

.DISCUSSION...AS OF 2:58 PM PDT MONDAY...DEEP 2500 FOOT MARINE
LAYER IN PLACE WITH SFO-SAC ONSHORE FLOW CURRENTLY 2.8 MB KEEPING
ONSHORE WINDS STRONG THROUGH THE DELTA. TEMPERATURES IN THE CITY
AND HERE AT THE OFFICE IN MONTEREY CURRENTLY A COOL 57 AS OF 2 PM
WITH LIVERMORE ONLY 71 WITH A 15 MPH WEST WIND. CONVECTION HAS
FIRED ACROSS MOST OF THE HIGHER MOUNTAINS ACROSS THE STATE WITH
DEBRIS CLOUDS OFF THE SIERRA CURRENTLY ROTATING IN AN EAST TO WEST
DIRECTION DUE TO THE CIRCULATION OF LOW PRESSURE OVER SOUTHERN
CALIFORNIA AND A WEAK UPPER HIGH OVER OREGON. NOT OUT OF THE
QUESTION THAT A FEW HIGH LEVEL DEBRIS CLOUDS COULD DRIFT OVER THE
EAST BAY BY LATER THIS EVENING. SO FAR ONLY SOME CUMULUS CLOUDS
HAVE DEVELOPED OVER THE HIGHEST INTERIOR HILLS OF SAN BENITO
COUNTY THIS AFTERNOON WHICH MODELS HAVE HANDLED FAIRLY WELL.

LOOKING AHEAD...EXPECT THE MARINE LAYER TO STAY AT LEAST 2500 FEET
DEEP TONIGHT AND MAY EVEN APPROACH 3000 FEET ALLOWING FOR ANOTHER
DEEP INLAND PUSH OF MARINE CLOUDS BY TUESDAY MORNING. IN GENERAL
JUST GOING WITH A PERSISTENCE FORECAST IN TERMS OF TEMPERATURE ON TUESDAY.

IN GENERAL THE MODELS HAVE KEPT BACKING OFF ON ANY SHOWER CHANCES
FOR OUR CWA THE NEXT SEVERAL DAYS AS AN UPPER LEVEL TROUGH
APPROACHES WHILE AFTERNOON CONVECTION LOOKS TO OCCUR EACH DAY OVER
THE SIERRA AND NORTHERN MOUNTAINS. HAVE MAINTAINED SOME VERY LOW
AFTERNOON SHOWER/T-STORM CHANCES OVER THE HIGHER TERRAIN OF SAN
BENITO COUNTY AND ALONG THE NAPA/LAKE COUNTY BORDER. HOWEVER FOR
THE MAJORITY OF FOLKS THE MAIN WEATHER THEME WILL BE A MORE
TYPICAL NIGHT AND MORNING LOW CLOUD DECK CLEARING BACK TO THE
COAST TYPE OF FORECAST.

UNFORTUNATELY THE LONG RANGE MODELS HAVE BACKED OFF ON ANY
APPRECIABLE RAIN CHANCES FOR OUR CWA. THE 12Z ECMWF NOW BUILDS A
RIDGE OVER THE BAY AREA THIS WEEKEND AS AN INSIDE SLIDER DIVES
INTO NEVADA ON SATURDAY MORNING. SO IF ANYTHING THE TREND FOR THE
WEEKEND LOOKS WARMER WITH INCREASED COASTAL SUNSHINE.

GIVEN THE TRENDS ON ECMWF/CMC AND GFS MODELS HAVE PULLED POPS FROM
THE LONG RANGE FORECAST THAT PREVIOUSLY INCLUDED SLIGHT CHANCE OF
RAIN FOR THE NORTH BAY.

&&

.AVIATION...AS OF 5:00 PM PDT MONDAY...MAINLY CLEAR SKIES PREVAIL
OVER MOST TERMINALS WITH THE EXCEPTION OF KMTR AND KSNS. STRATUS
WILL MAKE AN EARLY RETURN TONIGHT WITH LOW CLOUDS EXPECTED TO
PUSH INLAND AROUND 03Z-04Z THIS EVENING. BORDERLINE IFR/MVFR CIGS
EXPECTED. ONSHORE WINDS WILL BE GUSTY ALONG THE EDGES OF THE
STRATUS FIELD AS WELL AS THROUGH AREAS WHERE THE WIND IS FUNNELED
THROUGH COASTAL GAPS. SPEEDS SHOULD CONTINUE AROUND 10 TO 15 KT
WITH GUSTS AROUND 20 KT THROUGH THIS EVENING BEFORE EASING AND
BECOMING LIGHT OVERNIGHT. A SIMILAR CLEARING TIME IS EXPECTED
TUESDAY MORNING AROUND 19Z-20Z. MODERATELY HIGH CONFIDENCE.

VICINITY OF KSFO...VFR CIGS WILL TRANSITIONS TO BORDERLINE
IFR/MVFR CIGS AROUND 03Z-04Z THIS EVENING. UNTIL THEN...MODERATE
WEST WINDS AROUND 15 KT WITH OCCASIONALLY GUSTS TO AROUND 20 KT ARE
EXPECTED. WINDS WILL EASE TO 10 KT OR LESS OVERNIGHT. CLEARING IS
ANTICIPATED AROUND 20Z TUESDAY MORNING. MODERATELY HIGH CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...MVFR CIGS WILL LOWER TO VFR EARLY
THIS EVENING. WEST TO SOUTHWEST WINDS AROUND 10 KT EXPECTED
THROUGH THE EVENING WITH LIGHTER WINDS ANTICIPATED OVERNIGHT. CIGS
WILL LIFT TO MVFR AROUND 19Z-20Z TUESDAY MORNING BUT ARE NOT
FORECAST TO CLEAR.

&&

.MARINE...AS OF 2:18 PM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS  HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE  FOR ZONES NORTH OF POINT
REYES WITH GALE FORCE WINDS EXPECTED IN THE  OUTER ZONE BY LATE
TUESDAY AFTERNOON. IN ADDITION...SHORT PERIOD NORTHWESTERLY SWELL
WILL GREATLY BUILD FOR THE NORTHERN OUTER ZONES ALSO BY TUESDAY
NIGHT.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM FROM 3 AM
             SCA...SF BAY NORTH OF THE BAY BRIDGE UNTIL 3 AM

&&

$$

PUBLIC FORECAST: RWW
AVIATION: CW
MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 202158
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
258 PM PDT MON APR 20 2015

.SYNOPSIS...A DEEP MARINE LAYER WILL ALLOW LOW CLOUDS TO SPREAD
WELL INLAND DURING THE NIGHT AND MORNING HOURS ACROSS THE BAY AREA
THE NEXT FEW DAYS KEEPING TEMPERATURES NEAR OR SLIGHTLY BELOW
NORMAL. AN UPPER LOW OVER THE REGION MAY GENERATE SOME NIGHT AND
MORNING DRIZZLE ALONG WITH SOME AFTERNOON CUMULUS BUILD-UPS OVER
THE REMOTE INTERIOR HILLS THE COULD LEAD TO AN OUTSIDE CHANCE OF A
STRAY SHOWER OR ISOLATED THUNDERSTORM.

&&

.DISCUSSION...AS OF 2:58 PM PDT MONDAY...DEEP 2500 FOOT MARINE
LAYER IN PLACE WITH SFO-SAC ONSHORE FLOW CURRENTLY 2.8 MB KEEPING
ONSHORE WINDS STRONG THROUGH THE DELTA. TEMPERATURES IN THE CITY
AND HERE AT THE OFFICE IN MONTEREY CURRENTLY A COOL 57 AS OF 2 PM
WITH LIVERMORE ONLY 71 WITH A 15 MPH WEST WIND. CONVECTION HAS
FIRED ACROSS MOST OF THE HIGHER MOUNTAINS ACROSS THE STATE WITH
DEBRIS CLOUDS OFF THE SIERRA CURRENTLY ROTATING IN AN EAST TO WEST
DIRECTION DUE TO THE CIRCULATION OF LOW PRESSURE OVER SOUTHERN
CALIFORNIA AND A WEAK UPPER HIGH OVER OREGON. NOT OUT OF THE
QUESTION THAT A FEW HIGH LEVEL DEBRIS CLOUDS COULD DRIFT OVER THE
EAST BAY BY LATER THIS EVENING. SO FAR ONLY SOME CUMULUS CLOUDS
HAVE DEVELOPED OVER THE HIGHEST INTERIOR HILLS OF SAN BENITO
COUNTY THIS AFTERNOON WHICH MODELS HAVE HANDLED FAIRLY WELL.

LOOKING AHEAD...EXPECT THE MARINE LAYER TO STAY AT LEAST 2500 FEET
DEEP TONIGHT AND MAY EVEN APPROACH 3000 FEET ALLOWING FOR ANOTHER
DEEP INLAND PUSH OF MARINE CLOUDS BY TUESDAY MORNING. IN GENERAL
JUST GOING WITH A PERSISTENCE FORECAST IN TERMS OF TEMPERATURE ON TUESDAY.

IN GENERAL THE MODELS HAVE KEPT BACKING OFF ON ANY SHOWER CHANCES
FOR OUR CWA THE NEXT SEVERAL DAYS AS AN UPPER LEVEL TROUGH
APPROACHES WHILE AFTERNOON CONVECTION LOOKS TO OCCUR EACH DAY OVER
THE SIERRA AND NORTHERN MOUNTAINS. HAVE MAINTAINED SOME VERY LOW
AFTERNOON SHOWER/T-STORM CHANCES OVER THE HIGHER TERRAIN OF SAN
BENITO COUNTY AND ALONG THE NAPA/LAKE COUNTY BORDER. HOWEVER FOR
THE MAJORITY OF FOLKS THE MAIN WEATHER THEME WILL BE A MORE
TYPICAL NIGHT AND MORNING LOW CLOUD DECK CLEARING BACK TO THE
COAST TYPE OF FORECAST.

UNFORTUNATELY THE LONG RANGE MODELS HAVE BACKED OFF ON ANY
APPRECIABLE RAIN CHANCES FOR OUR CWA. THE 12Z ECMWF NOW BUILDS A
RIDGE OVER THE BAY AREA THIS WEEKEND AS AN INSIDE SLIDER DIVES
INTO NEVADA ON SATURDAY MORNING. SO IF ANYTHING THE TREND FOR THE
WEEKEND LOOKS WARMER WITH INCREASED COASTAL SUNSHINE.

GIVEN THE TRENDS ON ECMWF/CMC AND GFS MODELS HAVE PULLED POPS FROM
THE LONG RANGE FORECAST THAT PREVIOUSLY INCLUDED SLIGHT CHANCE OF
RAIN FOR THE NORTH BAY.

&&

.AVIATION...AS OF 11:00 AM PDT MONDAY...STILL HAVE WIDESPREAD
CLOUDS ACROSS A GOOD PORTION OF OUR AREA ALTHOUGH LAST FEW FRAMES
SHOW IT IS DEFINITELY DIMINISHING. FOR THE TAF PACKAGE ONLY MADE A
FEW MINOR CHANGES TO THE BURN-OFF TIMES AND CONDITIONS FOR TODAY.
WOULD EXPECT ALL TERMINALS TO BE BACK TO VFR BY 20Z. WIND WILL
PICK UP OVER THE AFTERNOON WITH TYPICAL SEA BREEZES EXPECT. SPEEDS
SHOULD GENERALLY BE UNDER 15 KT. MVFR TO POSSIBLE IFR RETURNS
TONIGHT. WITH A DEEP MARINE LAYER PLUS WIND EXPECTED TO STAY 270
TO 290 FORECAST CALLS FOR VFR BREAK-OUT TO BE ABOUT THE SAME OR
EVEN AN HOUR OR TWO LATER FOR TOMORROW. OVERALL MODERATE
CONFIDENCE.

VICINITY OF KSFO...SATELLITE AND CAMS SHOW CLOUDS STARTING TO THIN
OUT JUST TO THE SOUTH WITH BKN-OVC MVFR CIGS FORECAST TIL 19Z.
WESTERLY WINDS ARE LIKELY TO REMAIN UNDER 20 KNOTS TODAY. MVFR
RETURNS AROUND 04Z. MODERATE TO HIGH CONFIDENCE FOR TODAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS EXPECTED 19-20Z FOLLOWED BY
PARTIAL CLEARING FOR THE AFTERNOON HOURS. PERSISTENCE FORECAST FOR
THE EVENING...STRATUS IS LIKELY TO RETURN EARLY BETWEEN 01 AND
02Z.

&&

.MARINE...AS OF 02:40 PM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS  HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE  FOR ZONES NORTH OF POINT
REYES WITH GALE FORCE WINDS EXPECTED IN THE  OUTER ZONE BY LATE
TUESDAY AFTERNOON. IN ADDITION...SHORT PERIOD NORTHWESTERLY SWELL
WILL GREATLY BUILD FOR THE NORTHERN OUTER ZONES ALSO BY TUESDAY
NIGHT.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM FROM 3 AM
             SCA...SF BAY NORTH OF THE BAY BRIDGE UNTIL 3 AM

&&

$$

PUBLIC FORECAST: RWW
AVIATION/MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 202158
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
258 PM PDT MON APR 20 2015

.SYNOPSIS...A DEEP MARINE LAYER WILL ALLOW LOW CLOUDS TO SPREAD
WELL INLAND DURING THE NIGHT AND MORNING HOURS ACROSS THE BAY AREA
THE NEXT FEW DAYS KEEPING TEMPERATURES NEAR OR SLIGHTLY BELOW
NORMAL. AN UPPER LOW OVER THE REGION MAY GENERATE SOME NIGHT AND
MORNING DRIZZLE ALONG WITH SOME AFTERNOON CUMULUS BUILD-UPS OVER
THE REMOTE INTERIOR HILLS THE COULD LEAD TO AN OUTSIDE CHANCE OF A
STRAY SHOWER OR ISOLATED THUNDERSTORM.

&&

.DISCUSSION...AS OF 2:58 PM PDT MONDAY...DEEP 2500 FOOT MARINE
LAYER IN PLACE WITH SFO-SAC ONSHORE FLOW CURRENTLY 2.8 MB KEEPING
ONSHORE WINDS STRONG THROUGH THE DELTA. TEMPERATURES IN THE CITY
AND HERE AT THE OFFICE IN MONTEREY CURRENTLY A COOL 57 AS OF 2 PM
WITH LIVERMORE ONLY 71 WITH A 15 MPH WEST WIND. CONVECTION HAS
FIRED ACROSS MOST OF THE HIGHER MOUNTAINS ACROSS THE STATE WITH
DEBRIS CLOUDS OFF THE SIERRA CURRENTLY ROTATING IN AN EAST TO WEST
DIRECTION DUE TO THE CIRCULATION OF LOW PRESSURE OVER SOUTHERN
CALIFORNIA AND A WEAK UPPER HIGH OVER OREGON. NOT OUT OF THE
QUESTION THAT A FEW HIGH LEVEL DEBRIS CLOUDS COULD DRIFT OVER THE
EAST BAY BY LATER THIS EVENING. SO FAR ONLY SOME CUMULUS CLOUDS
HAVE DEVELOPED OVER THE HIGHEST INTERIOR HILLS OF SAN BENITO
COUNTY THIS AFTERNOON WHICH MODELS HAVE HANDLED FAIRLY WELL.

LOOKING AHEAD...EXPECT THE MARINE LAYER TO STAY AT LEAST 2500 FEET
DEEP TONIGHT AND MAY EVEN APPROACH 3000 FEET ALLOWING FOR ANOTHER
DEEP INLAND PUSH OF MARINE CLOUDS BY TUESDAY MORNING. IN GENERAL
JUST GOING WITH A PERSISTENCE FORECAST IN TERMS OF TEMPERATURE ON TUESDAY.

IN GENERAL THE MODELS HAVE KEPT BACKING OFF ON ANY SHOWER CHANCES
FOR OUR CWA THE NEXT SEVERAL DAYS AS AN UPPER LEVEL TROUGH
APPROACHES WHILE AFTERNOON CONVECTION LOOKS TO OCCUR EACH DAY OVER
THE SIERRA AND NORTHERN MOUNTAINS. HAVE MAINTAINED SOME VERY LOW
AFTERNOON SHOWER/T-STORM CHANCES OVER THE HIGHER TERRAIN OF SAN
BENITO COUNTY AND ALONG THE NAPA/LAKE COUNTY BORDER. HOWEVER FOR
THE MAJORITY OF FOLKS THE MAIN WEATHER THEME WILL BE A MORE
TYPICAL NIGHT AND MORNING LOW CLOUD DECK CLEARING BACK TO THE
COAST TYPE OF FORECAST.

UNFORTUNATELY THE LONG RANGE MODELS HAVE BACKED OFF ON ANY
APPRECIABLE RAIN CHANCES FOR OUR CWA. THE 12Z ECMWF NOW BUILDS A
RIDGE OVER THE BAY AREA THIS WEEKEND AS AN INSIDE SLIDER DIVES
INTO NEVADA ON SATURDAY MORNING. SO IF ANYTHING THE TREND FOR THE
WEEKEND LOOKS WARMER WITH INCREASED COASTAL SUNSHINE.

GIVEN THE TRENDS ON ECMWF/CMC AND GFS MODELS HAVE PULLED POPS FROM
THE LONG RANGE FORECAST THAT PREVIOUSLY INCLUDED SLIGHT CHANCE OF
RAIN FOR THE NORTH BAY.

&&

.AVIATION...AS OF 11:00 AM PDT MONDAY...STILL HAVE WIDESPREAD
CLOUDS ACROSS A GOOD PORTION OF OUR AREA ALTHOUGH LAST FEW FRAMES
SHOW IT IS DEFINITELY DIMINISHING. FOR THE TAF PACKAGE ONLY MADE A
FEW MINOR CHANGES TO THE BURN-OFF TIMES AND CONDITIONS FOR TODAY.
WOULD EXPECT ALL TERMINALS TO BE BACK TO VFR BY 20Z. WIND WILL
PICK UP OVER THE AFTERNOON WITH TYPICAL SEA BREEZES EXPECT. SPEEDS
SHOULD GENERALLY BE UNDER 15 KT. MVFR TO POSSIBLE IFR RETURNS
TONIGHT. WITH A DEEP MARINE LAYER PLUS WIND EXPECTED TO STAY 270
TO 290 FORECAST CALLS FOR VFR BREAK-OUT TO BE ABOUT THE SAME OR
EVEN AN HOUR OR TWO LATER FOR TOMORROW. OVERALL MODERATE
CONFIDENCE.

VICINITY OF KSFO...SATELLITE AND CAMS SHOW CLOUDS STARTING TO THIN
OUT JUST TO THE SOUTH WITH BKN-OVC MVFR CIGS FORECAST TIL 19Z.
WESTERLY WINDS ARE LIKELY TO REMAIN UNDER 20 KNOTS TODAY. MVFR
RETURNS AROUND 04Z. MODERATE TO HIGH CONFIDENCE FOR TODAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS EXPECTED 19-20Z FOLLOWED BY
PARTIAL CLEARING FOR THE AFTERNOON HOURS. PERSISTENCE FORECAST FOR
THE EVENING...STRATUS IS LIKELY TO RETURN EARLY BETWEEN 01 AND
02Z.

&&

.MARINE...AS OF 02:40 PM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS  HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE  FOR ZONES NORTH OF POINT
REYES WITH GALE FORCE WINDS EXPECTED IN THE  OUTER ZONE BY LATE
TUESDAY AFTERNOON. IN ADDITION...SHORT PERIOD NORTHWESTERLY SWELL
WILL GREATLY BUILD FOR THE NORTHERN OUTER ZONES ALSO BY TUESDAY
NIGHT.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM FROM 3 AM
             SCA...SF BAY NORTH OF THE BAY BRIDGE UNTIL 3 AM

&&

$$

PUBLIC FORECAST: RWW
AVIATION/MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 202158
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
258 PM PDT MON APR 20 2015

.SYNOPSIS...A DEEP MARINE LAYER WILL ALLOW LOW CLOUDS TO SPREAD
WELL INLAND DURING THE NIGHT AND MORNING HOURS ACROSS THE BAY AREA
THE NEXT FEW DAYS KEEPING TEMPERATURES NEAR OR SLIGHTLY BELOW
NORMAL. AN UPPER LOW OVER THE REGION MAY GENERATE SOME NIGHT AND
MORNING DRIZZLE ALONG WITH SOME AFTERNOON CUMULUS BUILD-UPS OVER
THE REMOTE INTERIOR HILLS THE COULD LEAD TO AN OUTSIDE CHANCE OF A
STRAY SHOWER OR ISOLATED THUNDERSTORM.

&&

.DISCUSSION...AS OF 2:58 PM PDT MONDAY...DEEP 2500 FOOT MARINE
LAYER IN PLACE WITH SFO-SAC ONSHORE FLOW CURRENTLY 2.8 MB KEEPING
ONSHORE WINDS STRONG THROUGH THE DELTA. TEMPERATURES IN THE CITY
AND HERE AT THE OFFICE IN MONTEREY CURRENTLY A COOL 57 AS OF 2 PM
WITH LIVERMORE ONLY 71 WITH A 15 MPH WEST WIND. CONVECTION HAS
FIRED ACROSS MOST OF THE HIGHER MOUNTAINS ACROSS THE STATE WITH
DEBRIS CLOUDS OFF THE SIERRA CURRENTLY ROTATING IN AN EAST TO WEST
DIRECTION DUE TO THE CIRCULATION OF LOW PRESSURE OVER SOUTHERN
CALIFORNIA AND A WEAK UPPER HIGH OVER OREGON. NOT OUT OF THE
QUESTION THAT A FEW HIGH LEVEL DEBRIS CLOUDS COULD DRIFT OVER THE
EAST BAY BY LATER THIS EVENING. SO FAR ONLY SOME CUMULUS CLOUDS
HAVE DEVELOPED OVER THE HIGHEST INTERIOR HILLS OF SAN BENITO
COUNTY THIS AFTERNOON WHICH MODELS HAVE HANDLED FAIRLY WELL.

LOOKING AHEAD...EXPECT THE MARINE LAYER TO STAY AT LEAST 2500 FEET
DEEP TONIGHT AND MAY EVEN APPROACH 3000 FEET ALLOWING FOR ANOTHER
DEEP INLAND PUSH OF MARINE CLOUDS BY TUESDAY MORNING. IN GENERAL
JUST GOING WITH A PERSISTENCE FORECAST IN TERMS OF TEMPERATURE ON TUESDAY.

IN GENERAL THE MODELS HAVE KEPT BACKING OFF ON ANY SHOWER CHANCES
FOR OUR CWA THE NEXT SEVERAL DAYS AS AN UPPER LEVEL TROUGH
APPROACHES WHILE AFTERNOON CONVECTION LOOKS TO OCCUR EACH DAY OVER
THE SIERRA AND NORTHERN MOUNTAINS. HAVE MAINTAINED SOME VERY LOW
AFTERNOON SHOWER/T-STORM CHANCES OVER THE HIGHER TERRAIN OF SAN
BENITO COUNTY AND ALONG THE NAPA/LAKE COUNTY BORDER. HOWEVER FOR
THE MAJORITY OF FOLKS THE MAIN WEATHER THEME WILL BE A MORE
TYPICAL NIGHT AND MORNING LOW CLOUD DECK CLEARING BACK TO THE
COAST TYPE OF FORECAST.

UNFORTUNATELY THE LONG RANGE MODELS HAVE BACKED OFF ON ANY
APPRECIABLE RAIN CHANCES FOR OUR CWA. THE 12Z ECMWF NOW BUILDS A
RIDGE OVER THE BAY AREA THIS WEEKEND AS AN INSIDE SLIDER DIVES
INTO NEVADA ON SATURDAY MORNING. SO IF ANYTHING THE TREND FOR THE
WEEKEND LOOKS WARMER WITH INCREASED COASTAL SUNSHINE.

GIVEN THE TRENDS ON ECMWF/CMC AND GFS MODELS HAVE PULLED POPS FROM
THE LONG RANGE FORECAST THAT PREVIOUSLY INCLUDED SLIGHT CHANCE OF
RAIN FOR THE NORTH BAY.

&&

.AVIATION...AS OF 11:00 AM PDT MONDAY...STILL HAVE WIDESPREAD
CLOUDS ACROSS A GOOD PORTION OF OUR AREA ALTHOUGH LAST FEW FRAMES
SHOW IT IS DEFINITELY DIMINISHING. FOR THE TAF PACKAGE ONLY MADE A
FEW MINOR CHANGES TO THE BURN-OFF TIMES AND CONDITIONS FOR TODAY.
WOULD EXPECT ALL TERMINALS TO BE BACK TO VFR BY 20Z. WIND WILL
PICK UP OVER THE AFTERNOON WITH TYPICAL SEA BREEZES EXPECT. SPEEDS
SHOULD GENERALLY BE UNDER 15 KT. MVFR TO POSSIBLE IFR RETURNS
TONIGHT. WITH A DEEP MARINE LAYER PLUS WIND EXPECTED TO STAY 270
TO 290 FORECAST CALLS FOR VFR BREAK-OUT TO BE ABOUT THE SAME OR
EVEN AN HOUR OR TWO LATER FOR TOMORROW. OVERALL MODERATE
CONFIDENCE.

VICINITY OF KSFO...SATELLITE AND CAMS SHOW CLOUDS STARTING TO THIN
OUT JUST TO THE SOUTH WITH BKN-OVC MVFR CIGS FORECAST TIL 19Z.
WESTERLY WINDS ARE LIKELY TO REMAIN UNDER 20 KNOTS TODAY. MVFR
RETURNS AROUND 04Z. MODERATE TO HIGH CONFIDENCE FOR TODAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS EXPECTED 19-20Z FOLLOWED BY
PARTIAL CLEARING FOR THE AFTERNOON HOURS. PERSISTENCE FORECAST FOR
THE EVENING...STRATUS IS LIKELY TO RETURN EARLY BETWEEN 01 AND
02Z.

&&

.MARINE...AS OF 02:40 PM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS  HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE  FOR ZONES NORTH OF POINT
REYES WITH GALE FORCE WINDS EXPECTED IN THE  OUTER ZONE BY LATE
TUESDAY AFTERNOON. IN ADDITION...SHORT PERIOD NORTHWESTERLY SWELL
WILL GREATLY BUILD FOR THE NORTHERN OUTER ZONES ALSO BY TUESDAY
NIGHT.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM FROM 3 AM
             SCA...SF BAY NORTH OF THE BAY BRIDGE UNTIL 3 AM

&&

$$

PUBLIC FORECAST: RWW
AVIATION/MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 202158
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
258 PM PDT MON APR 20 2015

.SYNOPSIS...A DEEP MARINE LAYER WILL ALLOW LOW CLOUDS TO SPREAD
WELL INLAND DURING THE NIGHT AND MORNING HOURS ACROSS THE BAY AREA
THE NEXT FEW DAYS KEEPING TEMPERATURES NEAR OR SLIGHTLY BELOW
NORMAL. AN UPPER LOW OVER THE REGION MAY GENERATE SOME NIGHT AND
MORNING DRIZZLE ALONG WITH SOME AFTERNOON CUMULUS BUILD-UPS OVER
THE REMOTE INTERIOR HILLS THE COULD LEAD TO AN OUTSIDE CHANCE OF A
STRAY SHOWER OR ISOLATED THUNDERSTORM.

&&

.DISCUSSION...AS OF 2:58 PM PDT MONDAY...DEEP 2500 FOOT MARINE
LAYER IN PLACE WITH SFO-SAC ONSHORE FLOW CURRENTLY 2.8 MB KEEPING
ONSHORE WINDS STRONG THROUGH THE DELTA. TEMPERATURES IN THE CITY
AND HERE AT THE OFFICE IN MONTEREY CURRENTLY A COOL 57 AS OF 2 PM
WITH LIVERMORE ONLY 71 WITH A 15 MPH WEST WIND. CONVECTION HAS
FIRED ACROSS MOST OF THE HIGHER MOUNTAINS ACROSS THE STATE WITH
DEBRIS CLOUDS OFF THE SIERRA CURRENTLY ROTATING IN AN EAST TO WEST
DIRECTION DUE TO THE CIRCULATION OF LOW PRESSURE OVER SOUTHERN
CALIFORNIA AND A WEAK UPPER HIGH OVER OREGON. NOT OUT OF THE
QUESTION THAT A FEW HIGH LEVEL DEBRIS CLOUDS COULD DRIFT OVER THE
EAST BAY BY LATER THIS EVENING. SO FAR ONLY SOME CUMULUS CLOUDS
HAVE DEVELOPED OVER THE HIGHEST INTERIOR HILLS OF SAN BENITO
COUNTY THIS AFTERNOON WHICH MODELS HAVE HANDLED FAIRLY WELL.

LOOKING AHEAD...EXPECT THE MARINE LAYER TO STAY AT LEAST 2500 FEET
DEEP TONIGHT AND MAY EVEN APPROACH 3000 FEET ALLOWING FOR ANOTHER
DEEP INLAND PUSH OF MARINE CLOUDS BY TUESDAY MORNING. IN GENERAL
JUST GOING WITH A PERSISTENCE FORECAST IN TERMS OF TEMPERATURE ON TUESDAY.

IN GENERAL THE MODELS HAVE KEPT BACKING OFF ON ANY SHOWER CHANCES
FOR OUR CWA THE NEXT SEVERAL DAYS AS AN UPPER LEVEL TROUGH
APPROACHES WHILE AFTERNOON CONVECTION LOOKS TO OCCUR EACH DAY OVER
THE SIERRA AND NORTHERN MOUNTAINS. HAVE MAINTAINED SOME VERY LOW
AFTERNOON SHOWER/T-STORM CHANCES OVER THE HIGHER TERRAIN OF SAN
BENITO COUNTY AND ALONG THE NAPA/LAKE COUNTY BORDER. HOWEVER FOR
THE MAJORITY OF FOLKS THE MAIN WEATHER THEME WILL BE A MORE
TYPICAL NIGHT AND MORNING LOW CLOUD DECK CLEARING BACK TO THE
COAST TYPE OF FORECAST.

UNFORTUNATELY THE LONG RANGE MODELS HAVE BACKED OFF ON ANY
APPRECIABLE RAIN CHANCES FOR OUR CWA. THE 12Z ECMWF NOW BUILDS A
RIDGE OVER THE BAY AREA THIS WEEKEND AS AN INSIDE SLIDER DIVES
INTO NEVADA ON SATURDAY MORNING. SO IF ANYTHING THE TREND FOR THE
WEEKEND LOOKS WARMER WITH INCREASED COASTAL SUNSHINE.

GIVEN THE TRENDS ON ECMWF/CMC AND GFS MODELS HAVE PULLED POPS FROM
THE LONG RANGE FORECAST THAT PREVIOUSLY INCLUDED SLIGHT CHANCE OF
RAIN FOR THE NORTH BAY.

&&

.AVIATION...AS OF 11:00 AM PDT MONDAY...STILL HAVE WIDESPREAD
CLOUDS ACROSS A GOOD PORTION OF OUR AREA ALTHOUGH LAST FEW FRAMES
SHOW IT IS DEFINITELY DIMINISHING. FOR THE TAF PACKAGE ONLY MADE A
FEW MINOR CHANGES TO THE BURN-OFF TIMES AND CONDITIONS FOR TODAY.
WOULD EXPECT ALL TERMINALS TO BE BACK TO VFR BY 20Z. WIND WILL
PICK UP OVER THE AFTERNOON WITH TYPICAL SEA BREEZES EXPECT. SPEEDS
SHOULD GENERALLY BE UNDER 15 KT. MVFR TO POSSIBLE IFR RETURNS
TONIGHT. WITH A DEEP MARINE LAYER PLUS WIND EXPECTED TO STAY 270
TO 290 FORECAST CALLS FOR VFR BREAK-OUT TO BE ABOUT THE SAME OR
EVEN AN HOUR OR TWO LATER FOR TOMORROW. OVERALL MODERATE
CONFIDENCE.

VICINITY OF KSFO...SATELLITE AND CAMS SHOW CLOUDS STARTING TO THIN
OUT JUST TO THE SOUTH WITH BKN-OVC MVFR CIGS FORECAST TIL 19Z.
WESTERLY WINDS ARE LIKELY TO REMAIN UNDER 20 KNOTS TODAY. MVFR
RETURNS AROUND 04Z. MODERATE TO HIGH CONFIDENCE FOR TODAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS EXPECTED 19-20Z FOLLOWED BY
PARTIAL CLEARING FOR THE AFTERNOON HOURS. PERSISTENCE FORECAST FOR
THE EVENING...STRATUS IS LIKELY TO RETURN EARLY BETWEEN 01 AND
02Z.

&&

.MARINE...AS OF 02:40 PM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS  HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE  FOR ZONES NORTH OF POINT
REYES WITH GALE FORCE WINDS EXPECTED IN THE  OUTER ZONE BY LATE
TUESDAY AFTERNOON. IN ADDITION...SHORT PERIOD NORTHWESTERLY SWELL
WILL GREATLY BUILD FOR THE NORTHERN OUTER ZONES ALSO BY TUESDAY
NIGHT.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM FROM 3 AM
             SCA...SF BAY NORTH OF THE BAY BRIDGE UNTIL 3 AM

&&

$$

PUBLIC FORECAST: RWW
AVIATION/MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 201800
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1100 AM PDT MON APR 20 2015

.SYNOPSIS...COOL CONDITIONS WILL PERSIST NEAR THE COAST TODAY WITH
WARM TEMPERATURES EXPECTED INLAND. TEMPERATURES COOL SLIGHTLY
REGION-WIDE BEGINNING TUESDAY AS A SERIES OF WEAK UPPER LEVEL
SYSTEMS PUSH ACROSS THE REGION. THESE WEAK WEATHER SYSTEMS WILL
PRODUCE A SLIGHT CHANCE OF SHOWERS AT TIMES TUESDAY THROUGH
THURSDAY...BUT MAINLY OVER THE INLAND MOUNTAINS.

&&

.DISCUSSION...AS OF 9:12 AM PDT MONDAY...DEEP MARINE LAYER IN
PLACE THIS MORNING TO AROUND 2500 FEET ALONG THE COAST WITH
STRATUS HAVING OVERSPREAD NEARLY ALL VALLEYS ACROSS THE DISTRICT
BELOW THIS ELEVATION. A WEAK UPPER LOW WEST OF LOS ANGELES WILL
KEEP THE MARINE LAYER DEEP WITH ONSHORE FLOW IN PLACE TODAY.
EXPECT FAIRLY SLOW BURN-OFF OF THE LOW CLOUDS TODAY GIVEN THE DEEP
LAYER WITH LITTLE OR NO CLEARING NEAR THE COAST AND SOME PARTS OF
THE BAY.

UPPER LOW OVER SOUTHERN CALIFORNIA WONT MOVE MUCH THROUGH WEDS
KEEPING CONDITIONS FAIRLY STATIC WITH A DEEP MARINE LAYER AND NEAR OR
BELOW NORMAL TEMPS. THIS FEATURE WILL HELP TO GENERATE AFTERNOON
SHOWERS AND T-STORMS OVER THE SIERRA AND OTHER HIGH MOUNTAINS OF
THE STATE BUT NOT EXPECTING ANY ACTIVITY OVER THE BAY AREA
HILLS...EXCEPTION BEING SOME LOCALIZED NIGHT AND MORNING DRIZZLE
DUE TO A DEEP MARINE LAYER.

MID AND LONG RANGE MODELS KEEP THE MAIN STORM TRACK JUST NORTH OF
THE BAY AREA. THE SYNOPTIC PATTERN LOOKS TO REMAIN FAIRLY ACTIVE
BUT AT THIS TIME IT LOOKS LIKE MOST RAINS WILL STAY ACROSS FAR
NORTHERN CALIFORNIA AND POINTS NORTHWARD.

&&

.PREV DISCUSSION...AS OF 4:37 AM PDT MONDAY...ONSHORE FLOW AND A
PERSISTENT MARINE LAYER GREATER THAN 2KFT DEEP HAS ALLOWED FOR LOW
CLOUDS TO ONCE AGAIN DEVELOP WELL INLAND INTO MOST VALLEY
LOCATIONS THIS MORNING. THIS HAS HELD OVERNIGHT TEMPERATURES IN
THE LOW/MID 50S REGION-WIDE. MEANWHILE...A WEAK MID/UPPER LEVEL
LOW PRESSURE SYSTEM CONTINUES TO DROP SOUTHWARD OFF OF THE CENTRAL
COAST AND WILL APPROACH THE SOUTHERN CALIFORNIA COAST DURING THE
NEXT 24 HOURS OR SO. AS THIS SYSTEM LINGERS OFF OF THE
COAST...WEATHER CONDITIONS TODAY WILL BE A NEAR REPEAT OF THOSE ON
SUNDAY. THUS...COOL TEMPERATURES NEAR THE COAST WHILE INLAND AREAS
ONCE AGAIN WARM INTO THE 70S AND LOWER 80S. IN ADDITION...THE
FORECAST MODELS KEEP THE BEST MID-LEVEL MOISTURE ASSOCIATED WITH
THIS SYSTEM WELL INLAND TODAY. WITH THAT...WILL MAINTAIN A DRY
FORECAST THROUGH THIS AFTERNOON/EVENING.

AS THE MARINE LAYER DEEPENS OVERNIGHT...PATCHY FOG AND DRIZZLE
WILL BE POSSIBLE ALONG THE COAST BY EARLY TUESDAY MORNING.
DAYTIME TEMPERATURES WILL FINALLY COOL INLAND THROUGH MIDWEEK AS
850MB CONDITIONS COOL AHEAD OF AN APPROACHING UPPER LEVEL TROUGH.
THE FORECAST MODELS CONTINUE TO STRUGGLE ON HOW MUCH MOISTURE
WILL BE ADVECTED INTO THE REGION WITH THIS SYSTEM...AND IF THE
ATMOSPHERE WILL BECOME UNSTABLE ENOUGH FOR SHOWERS/THUNDERSTORMS
TO DEVELOP OVER THE INLAND HILLS/MOUNTAINS. FOR NOW...WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORM OVER THE MOUNTAINS OF
SAN BENITO COUNTY FOR TUESDAY AFTERNOON/EVENING AND SHOWERS OVER
MUCH OF THE HIGHER TERRAIN ON WEDNESDAY. AS A BROAD MID/UPPER
LEVEL TROUGH REMAINS OVER MUCH OF THE WEST COAST THROUGH LATE
WEEK WITH WEAK DISTURBANCES MOVING ACROSS THE REGION...CANNOT
RULE OUT A FEW SHOWERS OVER THE INLAND HILLS/MOUNTAINS THROUGH
THURSDAY. THE MEDIUM RANGE MODELS NOW SHOW DRY CONDITIONS
RETURNING TO THE REGION FOR FRIDAY AS THE UPPER LEVEL TROUGH AXIS
SHIFTS INLAND. HAVING SAID ALL THAT...MOST LOCATIONS WILL SEE
LITTLE TO NO RAINFALL THROUGH LATE WEEK.

MUCH OF THE UPCOMING WEEKEND IS NOW FORECAST TO REMAIN DRY WITH
THE UPPER LEVEL STORM TRACK WELL TO THE NORTH. HOWEVER...WILL
CARRY A SLIGHT CHANCE OF PRECIPITATION OVER THE NORTH BAY SUNDAY
INTO MONDAY AS THE 12Z GFS PUSHES A SYSTEM INTO THE PACIFIC
NORTHWEST WITH TRAILING MOISTURE ALONG A FRONTAL BOUNDARY
DROPPING SOUTHWARD. MEANWHILE...THE CMC AND ECMWF MAINTAIN DRY
WEATHER CONDITIONS FOR LATE IN THE FORECAST PERIOD WITH WEAK
RIDING OVER CENTRAL CALIFORNIA. OVERALL...CHANCES FOR MEASURABLE
RAINFALL OVER THE REGION THROUGH THE END OF APRIL ARE LOOKING
MINIMAL AT BEST.

&&

.AVIATION...AS OF 11:00 AM PDT MONDAY...STILL HAVE WIDESPREAD
CLOUDS ACROSS A GOOD PORTION OF OUR AREA ALTHOUGH LAST FEW FRAMES
SHOW IT IS DEFINITELY DIMINISHING. FOR THE TAF PACKAGE ONLY MADE A
FEW MINOR CHANGES TO THE BURN-OFF TIMES AND CONDITIONS FOR TODAY.
WOULD EXPECT ALL TERMINALS TO BE BACK TO VFR BY 20Z. WIND WILL
PICK UP OVER THE AFTERNOON WITH TYPICAL SEA BREEZES EXPECT. SPEEDS
SHOULD GENERALLY BE UNDER 15 KT. MVFR TO POSSIBLE IFR RETURNS
TONIGHT. WITH A DEEP MARINE LAYER PLUS WIND EXPECTED TO STAY 270
TO 290 FORECAST CALLS FOR VRF BREAK-OUT TO BE ABOUT THE SAME OR
EVEN AN HOUR OR TWO LATER FOR TOMORROW. OVERALL MODERATE
CONFIDENCE.

VICINITY OF KSFO...SATELLITE AND CAMS SHOW CLOUDS STARTING TO THIN
OUT JUST TO THE SOUTH WITH BKN-OVC MVFR CIGS FORECAST TIL 19Z.
WESTERLY WINDS ARE LIKELY TO REMAIN UNDER 20 KNOTS TODAY. MVFR
RETURNS AROUND 04Z. MODERATE TO HIGH CONFIDENCE FOR TODAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS EXPECTED 19-20Z FOLLOWED BY
PARTIAL CLEARING FOR THE AFTERNOON HOURS. PERSISTENCE FORECAST FOR
THE EVENING...STRATUS IS LIKELY TO RETURN EARLY BETWEEN 01 AND
02Z.

&&

.MARINE...AS OF 08:53 AM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE FOR ZONES NORTH OF POINT
REYES.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...SF BAY NORTH OF THE BAY BRIDGE

&&

$$

PUBLIC FORECAST: RWW
AVIATION: BELL
MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 201800
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1100 AM PDT MON APR 20 2015

.SYNOPSIS...COOL CONDITIONS WILL PERSIST NEAR THE COAST TODAY WITH
WARM TEMPERATURES EXPECTED INLAND. TEMPERATURES COOL SLIGHTLY
REGION-WIDE BEGINNING TUESDAY AS A SERIES OF WEAK UPPER LEVEL
SYSTEMS PUSH ACROSS THE REGION. THESE WEAK WEATHER SYSTEMS WILL
PRODUCE A SLIGHT CHANCE OF SHOWERS AT TIMES TUESDAY THROUGH
THURSDAY...BUT MAINLY OVER THE INLAND MOUNTAINS.

&&

.DISCUSSION...AS OF 9:12 AM PDT MONDAY...DEEP MARINE LAYER IN
PLACE THIS MORNING TO AROUND 2500 FEET ALONG THE COAST WITH
STRATUS HAVING OVERSPREAD NEARLY ALL VALLEYS ACROSS THE DISTRICT
BELOW THIS ELEVATION. A WEAK UPPER LOW WEST OF LOS ANGELES WILL
KEEP THE MARINE LAYER DEEP WITH ONSHORE FLOW IN PLACE TODAY.
EXPECT FAIRLY SLOW BURN-OFF OF THE LOW CLOUDS TODAY GIVEN THE DEEP
LAYER WITH LITTLE OR NO CLEARING NEAR THE COAST AND SOME PARTS OF
THE BAY.

UPPER LOW OVER SOUTHERN CALIFORNIA WONT MOVE MUCH THROUGH WEDS
KEEPING CONDITIONS FAIRLY STATIC WITH A DEEP MARINE LAYER AND NEAR OR
BELOW NORMAL TEMPS. THIS FEATURE WILL HELP TO GENERATE AFTERNOON
SHOWERS AND T-STORMS OVER THE SIERRA AND OTHER HIGH MOUNTAINS OF
THE STATE BUT NOT EXPECTING ANY ACTIVITY OVER THE BAY AREA
HILLS...EXCEPTION BEING SOME LOCALIZED NIGHT AND MORNING DRIZZLE
DUE TO A DEEP MARINE LAYER.

MID AND LONG RANGE MODELS KEEP THE MAIN STORM TRACK JUST NORTH OF
THE BAY AREA. THE SYNOPTIC PATTERN LOOKS TO REMAIN FAIRLY ACTIVE
BUT AT THIS TIME IT LOOKS LIKE MOST RAINS WILL STAY ACROSS FAR
NORTHERN CALIFORNIA AND POINTS NORTHWARD.

&&

.PREV DISCUSSION...AS OF 4:37 AM PDT MONDAY...ONSHORE FLOW AND A
PERSISTENT MARINE LAYER GREATER THAN 2KFT DEEP HAS ALLOWED FOR LOW
CLOUDS TO ONCE AGAIN DEVELOP WELL INLAND INTO MOST VALLEY
LOCATIONS THIS MORNING. THIS HAS HELD OVERNIGHT TEMPERATURES IN
THE LOW/MID 50S REGION-WIDE. MEANWHILE...A WEAK MID/UPPER LEVEL
LOW PRESSURE SYSTEM CONTINUES TO DROP SOUTHWARD OFF OF THE CENTRAL
COAST AND WILL APPROACH THE SOUTHERN CALIFORNIA COAST DURING THE
NEXT 24 HOURS OR SO. AS THIS SYSTEM LINGERS OFF OF THE
COAST...WEATHER CONDITIONS TODAY WILL BE A NEAR REPEAT OF THOSE ON
SUNDAY. THUS...COOL TEMPERATURES NEAR THE COAST WHILE INLAND AREAS
ONCE AGAIN WARM INTO THE 70S AND LOWER 80S. IN ADDITION...THE
FORECAST MODELS KEEP THE BEST MID-LEVEL MOISTURE ASSOCIATED WITH
THIS SYSTEM WELL INLAND TODAY. WITH THAT...WILL MAINTAIN A DRY
FORECAST THROUGH THIS AFTERNOON/EVENING.

AS THE MARINE LAYER DEEPENS OVERNIGHT...PATCHY FOG AND DRIZZLE
WILL BE POSSIBLE ALONG THE COAST BY EARLY TUESDAY MORNING.
DAYTIME TEMPERATURES WILL FINALLY COOL INLAND THROUGH MIDWEEK AS
850MB CONDITIONS COOL AHEAD OF AN APPROACHING UPPER LEVEL TROUGH.
THE FORECAST MODELS CONTINUE TO STRUGGLE ON HOW MUCH MOISTURE
WILL BE ADVECTED INTO THE REGION WITH THIS SYSTEM...AND IF THE
ATMOSPHERE WILL BECOME UNSTABLE ENOUGH FOR SHOWERS/THUNDERSTORMS
TO DEVELOP OVER THE INLAND HILLS/MOUNTAINS. FOR NOW...WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORM OVER THE MOUNTAINS OF
SAN BENITO COUNTY FOR TUESDAY AFTERNOON/EVENING AND SHOWERS OVER
MUCH OF THE HIGHER TERRAIN ON WEDNESDAY. AS A BROAD MID/UPPER
LEVEL TROUGH REMAINS OVER MUCH OF THE WEST COAST THROUGH LATE
WEEK WITH WEAK DISTURBANCES MOVING ACROSS THE REGION...CANNOT
RULE OUT A FEW SHOWERS OVER THE INLAND HILLS/MOUNTAINS THROUGH
THURSDAY. THE MEDIUM RANGE MODELS NOW SHOW DRY CONDITIONS
RETURNING TO THE REGION FOR FRIDAY AS THE UPPER LEVEL TROUGH AXIS
SHIFTS INLAND. HAVING SAID ALL THAT...MOST LOCATIONS WILL SEE
LITTLE TO NO RAINFALL THROUGH LATE WEEK.

MUCH OF THE UPCOMING WEEKEND IS NOW FORECAST TO REMAIN DRY WITH
THE UPPER LEVEL STORM TRACK WELL TO THE NORTH. HOWEVER...WILL
CARRY A SLIGHT CHANCE OF PRECIPITATION OVER THE NORTH BAY SUNDAY
INTO MONDAY AS THE 12Z GFS PUSHES A SYSTEM INTO THE PACIFIC
NORTHWEST WITH TRAILING MOISTURE ALONG A FRONTAL BOUNDARY
DROPPING SOUTHWARD. MEANWHILE...THE CMC AND ECMWF MAINTAIN DRY
WEATHER CONDITIONS FOR LATE IN THE FORECAST PERIOD WITH WEAK
RIDING OVER CENTRAL CALIFORNIA. OVERALL...CHANCES FOR MEASURABLE
RAINFALL OVER THE REGION THROUGH THE END OF APRIL ARE LOOKING
MINIMAL AT BEST.

&&

.AVIATION...AS OF 11:00 AM PDT MONDAY...STILL HAVE WIDESPREAD
CLOUDS ACROSS A GOOD PORTION OF OUR AREA ALTHOUGH LAST FEW FRAMES
SHOW IT IS DEFINITELY DIMINISHING. FOR THE TAF PACKAGE ONLY MADE A
FEW MINOR CHANGES TO THE BURN-OFF TIMES AND CONDITIONS FOR TODAY.
WOULD EXPECT ALL TERMINALS TO BE BACK TO VFR BY 20Z. WIND WILL
PICK UP OVER THE AFTERNOON WITH TYPICAL SEA BREEZES EXPECT. SPEEDS
SHOULD GENERALLY BE UNDER 15 KT. MVFR TO POSSIBLE IFR RETURNS
TONIGHT. WITH A DEEP MARINE LAYER PLUS WIND EXPECTED TO STAY 270
TO 290 FORECAST CALLS FOR VRF BREAK-OUT TO BE ABOUT THE SAME OR
EVEN AN HOUR OR TWO LATER FOR TOMORROW. OVERALL MODERATE
CONFIDENCE.

VICINITY OF KSFO...SATELLITE AND CAMS SHOW CLOUDS STARTING TO THIN
OUT JUST TO THE SOUTH WITH BKN-OVC MVFR CIGS FORECAST TIL 19Z.
WESTERLY WINDS ARE LIKELY TO REMAIN UNDER 20 KNOTS TODAY. MVFR
RETURNS AROUND 04Z. MODERATE TO HIGH CONFIDENCE FOR TODAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS EXPECTED 19-20Z FOLLOWED BY
PARTIAL CLEARING FOR THE AFTERNOON HOURS. PERSISTENCE FORECAST FOR
THE EVENING...STRATUS IS LIKELY TO RETURN EARLY BETWEEN 01 AND
02Z.

&&

.MARINE...AS OF 08:53 AM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE FOR ZONES NORTH OF POINT
REYES.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...SF BAY NORTH OF THE BAY BRIDGE

&&

$$

PUBLIC FORECAST: RWW
AVIATION: BELL
MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 201800
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1100 AM PDT MON APR 20 2015

.SYNOPSIS...COOL CONDITIONS WILL PERSIST NEAR THE COAST TODAY WITH
WARM TEMPERATURES EXPECTED INLAND. TEMPERATURES COOL SLIGHTLY
REGION-WIDE BEGINNING TUESDAY AS A SERIES OF WEAK UPPER LEVEL
SYSTEMS PUSH ACROSS THE REGION. THESE WEAK WEATHER SYSTEMS WILL
PRODUCE A SLIGHT CHANCE OF SHOWERS AT TIMES TUESDAY THROUGH
THURSDAY...BUT MAINLY OVER THE INLAND MOUNTAINS.

&&

.DISCUSSION...AS OF 9:12 AM PDT MONDAY...DEEP MARINE LAYER IN
PLACE THIS MORNING TO AROUND 2500 FEET ALONG THE COAST WITH
STRATUS HAVING OVERSPREAD NEARLY ALL VALLEYS ACROSS THE DISTRICT
BELOW THIS ELEVATION. A WEAK UPPER LOW WEST OF LOS ANGELES WILL
KEEP THE MARINE LAYER DEEP WITH ONSHORE FLOW IN PLACE TODAY.
EXPECT FAIRLY SLOW BURN-OFF OF THE LOW CLOUDS TODAY GIVEN THE DEEP
LAYER WITH LITTLE OR NO CLEARING NEAR THE COAST AND SOME PARTS OF
THE BAY.

UPPER LOW OVER SOUTHERN CALIFORNIA WONT MOVE MUCH THROUGH WEDS
KEEPING CONDITIONS FAIRLY STATIC WITH A DEEP MARINE LAYER AND NEAR OR
BELOW NORMAL TEMPS. THIS FEATURE WILL HELP TO GENERATE AFTERNOON
SHOWERS AND T-STORMS OVER THE SIERRA AND OTHER HIGH MOUNTAINS OF
THE STATE BUT NOT EXPECTING ANY ACTIVITY OVER THE BAY AREA
HILLS...EXCEPTION BEING SOME LOCALIZED NIGHT AND MORNING DRIZZLE
DUE TO A DEEP MARINE LAYER.

MID AND LONG RANGE MODELS KEEP THE MAIN STORM TRACK JUST NORTH OF
THE BAY AREA. THE SYNOPTIC PATTERN LOOKS TO REMAIN FAIRLY ACTIVE
BUT AT THIS TIME IT LOOKS LIKE MOST RAINS WILL STAY ACROSS FAR
NORTHERN CALIFORNIA AND POINTS NORTHWARD.

&&

.PREV DISCUSSION...AS OF 4:37 AM PDT MONDAY...ONSHORE FLOW AND A
PERSISTENT MARINE LAYER GREATER THAN 2KFT DEEP HAS ALLOWED FOR LOW
CLOUDS TO ONCE AGAIN DEVELOP WELL INLAND INTO MOST VALLEY
LOCATIONS THIS MORNING. THIS HAS HELD OVERNIGHT TEMPERATURES IN
THE LOW/MID 50S REGION-WIDE. MEANWHILE...A WEAK MID/UPPER LEVEL
LOW PRESSURE SYSTEM CONTINUES TO DROP SOUTHWARD OFF OF THE CENTRAL
COAST AND WILL APPROACH THE SOUTHERN CALIFORNIA COAST DURING THE
NEXT 24 HOURS OR SO. AS THIS SYSTEM LINGERS OFF OF THE
COAST...WEATHER CONDITIONS TODAY WILL BE A NEAR REPEAT OF THOSE ON
SUNDAY. THUS...COOL TEMPERATURES NEAR THE COAST WHILE INLAND AREAS
ONCE AGAIN WARM INTO THE 70S AND LOWER 80S. IN ADDITION...THE
FORECAST MODELS KEEP THE BEST MID-LEVEL MOISTURE ASSOCIATED WITH
THIS SYSTEM WELL INLAND TODAY. WITH THAT...WILL MAINTAIN A DRY
FORECAST THROUGH THIS AFTERNOON/EVENING.

AS THE MARINE LAYER DEEPENS OVERNIGHT...PATCHY FOG AND DRIZZLE
WILL BE POSSIBLE ALONG THE COAST BY EARLY TUESDAY MORNING.
DAYTIME TEMPERATURES WILL FINALLY COOL INLAND THROUGH MIDWEEK AS
850MB CONDITIONS COOL AHEAD OF AN APPROACHING UPPER LEVEL TROUGH.
THE FORECAST MODELS CONTINUE TO STRUGGLE ON HOW MUCH MOISTURE
WILL BE ADVECTED INTO THE REGION WITH THIS SYSTEM...AND IF THE
ATMOSPHERE WILL BECOME UNSTABLE ENOUGH FOR SHOWERS/THUNDERSTORMS
TO DEVELOP OVER THE INLAND HILLS/MOUNTAINS. FOR NOW...WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORM OVER THE MOUNTAINS OF
SAN BENITO COUNTY FOR TUESDAY AFTERNOON/EVENING AND SHOWERS OVER
MUCH OF THE HIGHER TERRAIN ON WEDNESDAY. AS A BROAD MID/UPPER
LEVEL TROUGH REMAINS OVER MUCH OF THE WEST COAST THROUGH LATE
WEEK WITH WEAK DISTURBANCES MOVING ACROSS THE REGION...CANNOT
RULE OUT A FEW SHOWERS OVER THE INLAND HILLS/MOUNTAINS THROUGH
THURSDAY. THE MEDIUM RANGE MODELS NOW SHOW DRY CONDITIONS
RETURNING TO THE REGION FOR FRIDAY AS THE UPPER LEVEL TROUGH AXIS
SHIFTS INLAND. HAVING SAID ALL THAT...MOST LOCATIONS WILL SEE
LITTLE TO NO RAINFALL THROUGH LATE WEEK.

MUCH OF THE UPCOMING WEEKEND IS NOW FORECAST TO REMAIN DRY WITH
THE UPPER LEVEL STORM TRACK WELL TO THE NORTH. HOWEVER...WILL
CARRY A SLIGHT CHANCE OF PRECIPITATION OVER THE NORTH BAY SUNDAY
INTO MONDAY AS THE 12Z GFS PUSHES A SYSTEM INTO THE PACIFIC
NORTHWEST WITH TRAILING MOISTURE ALONG A FRONTAL BOUNDARY
DROPPING SOUTHWARD. MEANWHILE...THE CMC AND ECMWF MAINTAIN DRY
WEATHER CONDITIONS FOR LATE IN THE FORECAST PERIOD WITH WEAK
RIDING OVER CENTRAL CALIFORNIA. OVERALL...CHANCES FOR MEASURABLE
RAINFALL OVER THE REGION THROUGH THE END OF APRIL ARE LOOKING
MINIMAL AT BEST.

&&

.AVIATION...AS OF 11:00 AM PDT MONDAY...STILL HAVE WIDESPREAD
CLOUDS ACROSS A GOOD PORTION OF OUR AREA ALTHOUGH LAST FEW FRAMES
SHOW IT IS DEFINITELY DIMINISHING. FOR THE TAF PACKAGE ONLY MADE A
FEW MINOR CHANGES TO THE BURN-OFF TIMES AND CONDITIONS FOR TODAY.
WOULD EXPECT ALL TERMINALS TO BE BACK TO VFR BY 20Z. WIND WILL
PICK UP OVER THE AFTERNOON WITH TYPICAL SEA BREEZES EXPECT. SPEEDS
SHOULD GENERALLY BE UNDER 15 KT. MVFR TO POSSIBLE IFR RETURNS
TONIGHT. WITH A DEEP MARINE LAYER PLUS WIND EXPECTED TO STAY 270
TO 290 FORECAST CALLS FOR VRF BREAK-OUT TO BE ABOUT THE SAME OR
EVEN AN HOUR OR TWO LATER FOR TOMORROW. OVERALL MODERATE
CONFIDENCE.

VICINITY OF KSFO...SATELLITE AND CAMS SHOW CLOUDS STARTING TO THIN
OUT JUST TO THE SOUTH WITH BKN-OVC MVFR CIGS FORECAST TIL 19Z.
WESTERLY WINDS ARE LIKELY TO REMAIN UNDER 20 KNOTS TODAY. MVFR
RETURNS AROUND 04Z. MODERATE TO HIGH CONFIDENCE FOR TODAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS EXPECTED 19-20Z FOLLOWED BY
PARTIAL CLEARING FOR THE AFTERNOON HOURS. PERSISTENCE FORECAST FOR
THE EVENING...STRATUS IS LIKELY TO RETURN EARLY BETWEEN 01 AND
02Z.

&&

.MARINE...AS OF 08:53 AM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE FOR ZONES NORTH OF POINT
REYES.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...SF BAY NORTH OF THE BAY BRIDGE

&&

$$

PUBLIC FORECAST: RWW
AVIATION: BELL
MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 201800
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1100 AM PDT MON APR 20 2015

.SYNOPSIS...COOL CONDITIONS WILL PERSIST NEAR THE COAST TODAY WITH
WARM TEMPERATURES EXPECTED INLAND. TEMPERATURES COOL SLIGHTLY
REGION-WIDE BEGINNING TUESDAY AS A SERIES OF WEAK UPPER LEVEL
SYSTEMS PUSH ACROSS THE REGION. THESE WEAK WEATHER SYSTEMS WILL
PRODUCE A SLIGHT CHANCE OF SHOWERS AT TIMES TUESDAY THROUGH
THURSDAY...BUT MAINLY OVER THE INLAND MOUNTAINS.

&&

.DISCUSSION...AS OF 9:12 AM PDT MONDAY...DEEP MARINE LAYER IN
PLACE THIS MORNING TO AROUND 2500 FEET ALONG THE COAST WITH
STRATUS HAVING OVERSPREAD NEARLY ALL VALLEYS ACROSS THE DISTRICT
BELOW THIS ELEVATION. A WEAK UPPER LOW WEST OF LOS ANGELES WILL
KEEP THE MARINE LAYER DEEP WITH ONSHORE FLOW IN PLACE TODAY.
EXPECT FAIRLY SLOW BURN-OFF OF THE LOW CLOUDS TODAY GIVEN THE DEEP
LAYER WITH LITTLE OR NO CLEARING NEAR THE COAST AND SOME PARTS OF
THE BAY.

UPPER LOW OVER SOUTHERN CALIFORNIA WONT MOVE MUCH THROUGH WEDS
KEEPING CONDITIONS FAIRLY STATIC WITH A DEEP MARINE LAYER AND NEAR OR
BELOW NORMAL TEMPS. THIS FEATURE WILL HELP TO GENERATE AFTERNOON
SHOWERS AND T-STORMS OVER THE SIERRA AND OTHER HIGH MOUNTAINS OF
THE STATE BUT NOT EXPECTING ANY ACTIVITY OVER THE BAY AREA
HILLS...EXCEPTION BEING SOME LOCALIZED NIGHT AND MORNING DRIZZLE
DUE TO A DEEP MARINE LAYER.

MID AND LONG RANGE MODELS KEEP THE MAIN STORM TRACK JUST NORTH OF
THE BAY AREA. THE SYNOPTIC PATTERN LOOKS TO REMAIN FAIRLY ACTIVE
BUT AT THIS TIME IT LOOKS LIKE MOST RAINS WILL STAY ACROSS FAR
NORTHERN CALIFORNIA AND POINTS NORTHWARD.

&&

.PREV DISCUSSION...AS OF 4:37 AM PDT MONDAY...ONSHORE FLOW AND A
PERSISTENT MARINE LAYER GREATER THAN 2KFT DEEP HAS ALLOWED FOR LOW
CLOUDS TO ONCE AGAIN DEVELOP WELL INLAND INTO MOST VALLEY
LOCATIONS THIS MORNING. THIS HAS HELD OVERNIGHT TEMPERATURES IN
THE LOW/MID 50S REGION-WIDE. MEANWHILE...A WEAK MID/UPPER LEVEL
LOW PRESSURE SYSTEM CONTINUES TO DROP SOUTHWARD OFF OF THE CENTRAL
COAST AND WILL APPROACH THE SOUTHERN CALIFORNIA COAST DURING THE
NEXT 24 HOURS OR SO. AS THIS SYSTEM LINGERS OFF OF THE
COAST...WEATHER CONDITIONS TODAY WILL BE A NEAR REPEAT OF THOSE ON
SUNDAY. THUS...COOL TEMPERATURES NEAR THE COAST WHILE INLAND AREAS
ONCE AGAIN WARM INTO THE 70S AND LOWER 80S. IN ADDITION...THE
FORECAST MODELS KEEP THE BEST MID-LEVEL MOISTURE ASSOCIATED WITH
THIS SYSTEM WELL INLAND TODAY. WITH THAT...WILL MAINTAIN A DRY
FORECAST THROUGH THIS AFTERNOON/EVENING.

AS THE MARINE LAYER DEEPENS OVERNIGHT...PATCHY FOG AND DRIZZLE
WILL BE POSSIBLE ALONG THE COAST BY EARLY TUESDAY MORNING.
DAYTIME TEMPERATURES WILL FINALLY COOL INLAND THROUGH MIDWEEK AS
850MB CONDITIONS COOL AHEAD OF AN APPROACHING UPPER LEVEL TROUGH.
THE FORECAST MODELS CONTINUE TO STRUGGLE ON HOW MUCH MOISTURE
WILL BE ADVECTED INTO THE REGION WITH THIS SYSTEM...AND IF THE
ATMOSPHERE WILL BECOME UNSTABLE ENOUGH FOR SHOWERS/THUNDERSTORMS
TO DEVELOP OVER THE INLAND HILLS/MOUNTAINS. FOR NOW...WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORM OVER THE MOUNTAINS OF
SAN BENITO COUNTY FOR TUESDAY AFTERNOON/EVENING AND SHOWERS OVER
MUCH OF THE HIGHER TERRAIN ON WEDNESDAY. AS A BROAD MID/UPPER
LEVEL TROUGH REMAINS OVER MUCH OF THE WEST COAST THROUGH LATE
WEEK WITH WEAK DISTURBANCES MOVING ACROSS THE REGION...CANNOT
RULE OUT A FEW SHOWERS OVER THE INLAND HILLS/MOUNTAINS THROUGH
THURSDAY. THE MEDIUM RANGE MODELS NOW SHOW DRY CONDITIONS
RETURNING TO THE REGION FOR FRIDAY AS THE UPPER LEVEL TROUGH AXIS
SHIFTS INLAND. HAVING SAID ALL THAT...MOST LOCATIONS WILL SEE
LITTLE TO NO RAINFALL THROUGH LATE WEEK.

MUCH OF THE UPCOMING WEEKEND IS NOW FORECAST TO REMAIN DRY WITH
THE UPPER LEVEL STORM TRACK WELL TO THE NORTH. HOWEVER...WILL
CARRY A SLIGHT CHANCE OF PRECIPITATION OVER THE NORTH BAY SUNDAY
INTO MONDAY AS THE 12Z GFS PUSHES A SYSTEM INTO THE PACIFIC
NORTHWEST WITH TRAILING MOISTURE ALONG A FRONTAL BOUNDARY
DROPPING SOUTHWARD. MEANWHILE...THE CMC AND ECMWF MAINTAIN DRY
WEATHER CONDITIONS FOR LATE IN THE FORECAST PERIOD WITH WEAK
RIDING OVER CENTRAL CALIFORNIA. OVERALL...CHANCES FOR MEASURABLE
RAINFALL OVER THE REGION THROUGH THE END OF APRIL ARE LOOKING
MINIMAL AT BEST.

&&

.AVIATION...AS OF 11:00 AM PDT MONDAY...STILL HAVE WIDESPREAD
CLOUDS ACROSS A GOOD PORTION OF OUR AREA ALTHOUGH LAST FEW FRAMES
SHOW IT IS DEFINITELY DIMINISHING. FOR THE TAF PACKAGE ONLY MADE A
FEW MINOR CHANGES TO THE BURN-OFF TIMES AND CONDITIONS FOR TODAY.
WOULD EXPECT ALL TERMINALS TO BE BACK TO VFR BY 20Z. WIND WILL
PICK UP OVER THE AFTERNOON WITH TYPICAL SEA BREEZES EXPECT. SPEEDS
SHOULD GENERALLY BE UNDER 15 KT. MVFR TO POSSIBLE IFR RETURNS
TONIGHT. WITH A DEEP MARINE LAYER PLUS WIND EXPECTED TO STAY 270
TO 290 FORECAST CALLS FOR VRF BREAK-OUT TO BE ABOUT THE SAME OR
EVEN AN HOUR OR TWO LATER FOR TOMORROW. OVERALL MODERATE
CONFIDENCE.

VICINITY OF KSFO...SATELLITE AND CAMS SHOW CLOUDS STARTING TO THIN
OUT JUST TO THE SOUTH WITH BKN-OVC MVFR CIGS FORECAST TIL 19Z.
WESTERLY WINDS ARE LIKELY TO REMAIN UNDER 20 KNOTS TODAY. MVFR
RETURNS AROUND 04Z. MODERATE TO HIGH CONFIDENCE FOR TODAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS EXPECTED 19-20Z FOLLOWED BY
PARTIAL CLEARING FOR THE AFTERNOON HOURS. PERSISTENCE FORECAST FOR
THE EVENING...STRATUS IS LIKELY TO RETURN EARLY BETWEEN 01 AND
02Z.

&&

.MARINE...AS OF 08:53 AM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE FOR ZONES NORTH OF POINT
REYES.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...SF BAY NORTH OF THE BAY BRIDGE

&&

$$

PUBLIC FORECAST: RWW
AVIATION: BELL
MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 201612
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
912 AM PDT MON APR 20 2015

.SYNOPSIS...COOL CONDITIONS WILL PERSIST NEAR THE COAST TODAY WITH
WARM TEMPERATURES EXPECTED INLAND. TEMPERATURES COOL SLIGHTLY
REGION-WIDE BEGINNING TUESDAY AS A SERIES OF WEAK UPPER LEVEL
SYSTEMS PUSH ACROSS THE REGION. THESE WEAK WEATHER SYSTEMS WILL
PRODUCE A SLIGHT CHANCE OF SHOWERS AT TIMES TUESDAY THROUGH
THURSDAY...BUT MAINLY OVER THE INLAND MOUNTAINS.

&&

.DISCUSSION...AS OF 9:12 AM PDT MONDAY...DEEP MARINE LAYER IN
PLACE THIS MORNING TO AROUND 2500 FEET ALONG THE COAST WITH
STRATUS HAVING OVERSPREAD NEARLY ALL VALLEYS ACROSS THE DISTRICT
BELOW THIS ELEVATION. A WEAK UPPER LOW WEST OF LOS ANGELES WILL
KEEP THE MARINE LAYER DEEP WITH ONSHORE FLOW IN PLACE TODAY.
EXPECT FAIRLY SLOW BURN-OFF OF THE LOW CLOUDS TODAY GIVEN THE DEEP
LAYER WITH LITTLE OR NO CLEARING NEAR THE COAST AND SOME PARTS OF
THE BAY.

UPPER LOW OVER SOUTHERN CALIFORNIA WONT MOVE MUCH THROUGH WEDS
KEEPING CONDITIONS FAIRLY STATIC WITH A DEEP MARINE LAYER AND NEAR OR
BELOW NORMAL TEMPS. THIS FEATURE WILL HELP TO GENERATE AFTERNOON
SHOWERS AND T-STORMS OVER THE SIERRA AND OTHER HIGH MOUNTAINS OF
THE STATE BUT NOT EXPECTING ANY ACTIVITY OVER THE BAY AREA
HILLS...EXCEPTION BEING SOME LOCALIZED NIGHT AND MORNING DRIZZLE
DUE TO A DEEP MARINE LAYER.

MID AND LONG RANGE MODELS KEEP THE MAIN STORM TRACK JUST NORTH OF
THE BAY AREA. THE SYNOPTIC PATTERN LOOKS TO REMAIN FAIRLY ACTIVE
BUT AT THIS TIME IT LOOKS LIKE MOST RAINS WILL STAY ACROSS FAR
NORTHERN CALIFORNIA AND POINTS NORTHWARD.

&&

.PREV DISCUSSION...AS OF 4:37 AM PDT MONDAY...ONSHORE FLOW AND A
PERSISTENT MARINE LAYER GREATER THAN 2KFT DEEP HAS ALLOWED FOR LOW
CLOUDS TO ONCE AGAIN DEVELOP WELL INLAND INTO MOST VALLEY
LOCATIONS THIS MORNING. THIS HAS HELD OVERNIGHT TEMPERATURES IN
THE LOW/MID 50S REGION-WIDE. MEANWHILE...A WEAK MID/UPPER LEVEL
LOW PRESSURE SYSTEM CONTINUES TO DROP SOUTHWARD OFF OF THE CENTRAL
COAST AND WILL APPROACH THE SOUTHERN CALIFORNIA COAST DURING THE
NEXT 24 HOURS OR SO. AS THIS SYSTEM LINGERS OFF OF THE
COAST...WEATHER CONDITIONS TODAY WILL BE A NEAR REPEAT OF THOSE ON
SUNDAY. THUS...COOL TEMPERATURES NEAR THE COAST WHILE INLAND AREAS
ONCE AGAIN WARM INTO THE 70S AND LOWER 80S. IN ADDITION...THE
FORECAST MODELS KEEP THE BEST MID-LEVEL MOISTURE ASSOCIATED WITH
THIS SYSTEM WELL INLAND TODAY. WITH THAT...WILL MAINTAIN A DRY
FORECAST THROUGH THIS AFTERNOON/EVENING.

AS THE MARINE LAYER DEEPENS OVERNIGHT...PATCHY FOG AND DRIZZLE
WILL BE POSSIBLE ALONG THE COAST BY EARLY TUESDAY MORNING.
DAYTIME TEMPERATURES WILL FINALLY COOL INLAND THROUGH MIDWEEK AS
850MB CONDITIONS COOL AHEAD OF AN APPROACHING UPPER LEVEL TROUGH.
THE FORECAST MODELS CONTINUE TO STRUGGLE ON HOW MUCH MOISTURE
WILL BE ADVECTED INTO THE REGION WITH THIS SYSTEM...AND IF THE
ATMOSPHERE WILL BECOME UNSTABLE ENOUGH FOR SHOWERS/THUNDERSTORMS
TO DEVELOP OVER THE INLAND HILLS/MOUNTAINS. FOR NOW...WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORM OVER THE MOUNTAINS OF
SAN BENITO COUNTY FOR TUESDAY AFTERNOON/EVENING AND SHOWERS OVER
MUCH OF THE HIGHER TERRAIN ON WEDNESDAY. AS A BROAD MID/UPPER
LEVEL TROUGH REMAINS OVER MUCH OF THE WEST COAST THROUGH LATE
WEEK WITH WEAK DISTURBANCES MOVING ACROSS THE REGION...CANNOT
RULE OUT A FEW SHOWERS OVER THE INLAND HILLS/MOUNTAINS THROUGH
THURSDAY. THE MEDIUM RANGE MODELS NOW SHOW DRY CONDITIONS
RETURNING TO THE REGION FOR FRIDAY AS THE UPPER LEVEL TROUGH AXIS
SHIFTS INLAND. HAVING SAID ALL THAT...MOST LOCATIONS WILL SEE
LITTLE TO NO RAINFALL THROUGH LATE WEEK.

MUCH OF THE UPCOMING WEEKEND IS NOW FORECAST TO REMAIN DRY WITH
THE UPPER LEVEL STORM TRACK WELL TO THE NORTH. HOWEVER...WILL
CARRY A SLIGHT CHANCE OF PRECIPITATION OVER THE NORTH BAY SUNDAY
INTO MONDAY AS THE 12Z GFS PUSHES A SYSTEM INTO THE PACIFIC
NORTHWEST WITH TRAILING MOISTURE ALONG A FRONTAL BOUNDARY
DROPPING SOUTHWARD. MEANWHILE...THE CMC AND ECMWF MAINTAIN DRY
WEATHER CONDITIONS FOR LATE IN THE FORECAST PERIOD WITH WEAK
RIDING OVER CENTRAL CALIFORNIA. OVERALL...CHANCES FOR MEASURABLE
RAINFALL OVER THE REGION THROUGH THE END OF APRIL ARE LOOKING
MINIMAL AT BEST.

&&

.AVIATION...AS OF 5:21 AM PDT MONDAY...TODAY IS DAY 3 WITH
WIDESPREAD COASTAL STRATUS WITH A NOCTURNAL INLAND INTRUSION AS
SEEN ON SATELLITE RESULTING IN MVFR TO IFR CIGS AT AREA TERMINALS.
RECENT MODEL TRENDS HAVE SHOWN A DELAY IN THE LOW LEVEL COOLING
(850 MB PRESSURE LEVEL) ONCE EXPECTED TO ARRIVE AS SOON AS
TUESDAY...BUT NOW IT LOOKS LIKE IT`LL BE WEDNESDAY. THE MARINE
LAYER SHOULD HOLD TOGETHER FAIRLY WELL TODAY THROUGH TUESDAY
BEFORE ANY SIGNIFICANT WEAKENING MAY OCCUR MID TO LATE WEEK. THERE
MAY BE POCKETS OF LIGHT DRIZZLE AS A DEEPER MARINE LAYER
PERSISTS...BUT NONE SO FAR INDICATED IN METAR OBS. THE MARINE
LAYER IS PRESENTLY 2000-2400 FEET DEEP PER RECENT BODEGA
BAY...FORT ORD PROFILERS AND BAY AREA SODAR DATA.

VICINITY OF KSFO...BKN-OVC MVFR CIGS FORECAST TIL 19Z. WESTERLY
WINDS ARE LIKELY TO REMAIN UNDER 20 KNOTS TODAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS TIL 18Z FOLLOWED BY PARTIAL
CLEARING FOR THE AFTERNOON HOURS. PERSISTENCE FORECAST FOR THE
EVENING...STRATUS IS LIKELY TO RETURN EARLY.

&&

.MARINE...AS OF 08:53 AM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE FOR ZONES NORTH OF POINT
REYES.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...SF BAY NORTH OF THE BAY BRIDGE

&&

$$

PUBLIC FORECAST: RWW
AVIATION: CANEPA
MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 201612
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
912 AM PDT MON APR 20 2015

.SYNOPSIS...COOL CONDITIONS WILL PERSIST NEAR THE COAST TODAY WITH
WARM TEMPERATURES EXPECTED INLAND. TEMPERATURES COOL SLIGHTLY
REGION-WIDE BEGINNING TUESDAY AS A SERIES OF WEAK UPPER LEVEL
SYSTEMS PUSH ACROSS THE REGION. THESE WEAK WEATHER SYSTEMS WILL
PRODUCE A SLIGHT CHANCE OF SHOWERS AT TIMES TUESDAY THROUGH
THURSDAY...BUT MAINLY OVER THE INLAND MOUNTAINS.

&&

.DISCUSSION...AS OF 9:12 AM PDT MONDAY...DEEP MARINE LAYER IN
PLACE THIS MORNING TO AROUND 2500 FEET ALONG THE COAST WITH
STRATUS HAVING OVERSPREAD NEARLY ALL VALLEYS ACROSS THE DISTRICT
BELOW THIS ELEVATION. A WEAK UPPER LOW WEST OF LOS ANGELES WILL
KEEP THE MARINE LAYER DEEP WITH ONSHORE FLOW IN PLACE TODAY.
EXPECT FAIRLY SLOW BURN-OFF OF THE LOW CLOUDS TODAY GIVEN THE DEEP
LAYER WITH LITTLE OR NO CLEARING NEAR THE COAST AND SOME PARTS OF
THE BAY.

UPPER LOW OVER SOUTHERN CALIFORNIA WONT MOVE MUCH THROUGH WEDS
KEEPING CONDITIONS FAIRLY STATIC WITH A DEEP MARINE LAYER AND NEAR OR
BELOW NORMAL TEMPS. THIS FEATURE WILL HELP TO GENERATE AFTERNOON
SHOWERS AND T-STORMS OVER THE SIERRA AND OTHER HIGH MOUNTAINS OF
THE STATE BUT NOT EXPECTING ANY ACTIVITY OVER THE BAY AREA
HILLS...EXCEPTION BEING SOME LOCALIZED NIGHT AND MORNING DRIZZLE
DUE TO A DEEP MARINE LAYER.

MID AND LONG RANGE MODELS KEEP THE MAIN STORM TRACK JUST NORTH OF
THE BAY AREA. THE SYNOPTIC PATTERN LOOKS TO REMAIN FAIRLY ACTIVE
BUT AT THIS TIME IT LOOKS LIKE MOST RAINS WILL STAY ACROSS FAR
NORTHERN CALIFORNIA AND POINTS NORTHWARD.

&&

.PREV DISCUSSION...AS OF 4:37 AM PDT MONDAY...ONSHORE FLOW AND A
PERSISTENT MARINE LAYER GREATER THAN 2KFT DEEP HAS ALLOWED FOR LOW
CLOUDS TO ONCE AGAIN DEVELOP WELL INLAND INTO MOST VALLEY
LOCATIONS THIS MORNING. THIS HAS HELD OVERNIGHT TEMPERATURES IN
THE LOW/MID 50S REGION-WIDE. MEANWHILE...A WEAK MID/UPPER LEVEL
LOW PRESSURE SYSTEM CONTINUES TO DROP SOUTHWARD OFF OF THE CENTRAL
COAST AND WILL APPROACH THE SOUTHERN CALIFORNIA COAST DURING THE
NEXT 24 HOURS OR SO. AS THIS SYSTEM LINGERS OFF OF THE
COAST...WEATHER CONDITIONS TODAY WILL BE A NEAR REPEAT OF THOSE ON
SUNDAY. THUS...COOL TEMPERATURES NEAR THE COAST WHILE INLAND AREAS
ONCE AGAIN WARM INTO THE 70S AND LOWER 80S. IN ADDITION...THE
FORECAST MODELS KEEP THE BEST MID-LEVEL MOISTURE ASSOCIATED WITH
THIS SYSTEM WELL INLAND TODAY. WITH THAT...WILL MAINTAIN A DRY
FORECAST THROUGH THIS AFTERNOON/EVENING.

AS THE MARINE LAYER DEEPENS OVERNIGHT...PATCHY FOG AND DRIZZLE
WILL BE POSSIBLE ALONG THE COAST BY EARLY TUESDAY MORNING.
DAYTIME TEMPERATURES WILL FINALLY COOL INLAND THROUGH MIDWEEK AS
850MB CONDITIONS COOL AHEAD OF AN APPROACHING UPPER LEVEL TROUGH.
THE FORECAST MODELS CONTINUE TO STRUGGLE ON HOW MUCH MOISTURE
WILL BE ADVECTED INTO THE REGION WITH THIS SYSTEM...AND IF THE
ATMOSPHERE WILL BECOME UNSTABLE ENOUGH FOR SHOWERS/THUNDERSTORMS
TO DEVELOP OVER THE INLAND HILLS/MOUNTAINS. FOR NOW...WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORM OVER THE MOUNTAINS OF
SAN BENITO COUNTY FOR TUESDAY AFTERNOON/EVENING AND SHOWERS OVER
MUCH OF THE HIGHER TERRAIN ON WEDNESDAY. AS A BROAD MID/UPPER
LEVEL TROUGH REMAINS OVER MUCH OF THE WEST COAST THROUGH LATE
WEEK WITH WEAK DISTURBANCES MOVING ACROSS THE REGION...CANNOT
RULE OUT A FEW SHOWERS OVER THE INLAND HILLS/MOUNTAINS THROUGH
THURSDAY. THE MEDIUM RANGE MODELS NOW SHOW DRY CONDITIONS
RETURNING TO THE REGION FOR FRIDAY AS THE UPPER LEVEL TROUGH AXIS
SHIFTS INLAND. HAVING SAID ALL THAT...MOST LOCATIONS WILL SEE
LITTLE TO NO RAINFALL THROUGH LATE WEEK.

MUCH OF THE UPCOMING WEEKEND IS NOW FORECAST TO REMAIN DRY WITH
THE UPPER LEVEL STORM TRACK WELL TO THE NORTH. HOWEVER...WILL
CARRY A SLIGHT CHANCE OF PRECIPITATION OVER THE NORTH BAY SUNDAY
INTO MONDAY AS THE 12Z GFS PUSHES A SYSTEM INTO THE PACIFIC
NORTHWEST WITH TRAILING MOISTURE ALONG A FRONTAL BOUNDARY
DROPPING SOUTHWARD. MEANWHILE...THE CMC AND ECMWF MAINTAIN DRY
WEATHER CONDITIONS FOR LATE IN THE FORECAST PERIOD WITH WEAK
RIDING OVER CENTRAL CALIFORNIA. OVERALL...CHANCES FOR MEASURABLE
RAINFALL OVER THE REGION THROUGH THE END OF APRIL ARE LOOKING
MINIMAL AT BEST.

&&

.AVIATION...AS OF 5:21 AM PDT MONDAY...TODAY IS DAY 3 WITH
WIDESPREAD COASTAL STRATUS WITH A NOCTURNAL INLAND INTRUSION AS
SEEN ON SATELLITE RESULTING IN MVFR TO IFR CIGS AT AREA TERMINALS.
RECENT MODEL TRENDS HAVE SHOWN A DELAY IN THE LOW LEVEL COOLING
(850 MB PRESSURE LEVEL) ONCE EXPECTED TO ARRIVE AS SOON AS
TUESDAY...BUT NOW IT LOOKS LIKE IT`LL BE WEDNESDAY. THE MARINE
LAYER SHOULD HOLD TOGETHER FAIRLY WELL TODAY THROUGH TUESDAY
BEFORE ANY SIGNIFICANT WEAKENING MAY OCCUR MID TO LATE WEEK. THERE
MAY BE POCKETS OF LIGHT DRIZZLE AS A DEEPER MARINE LAYER
PERSISTS...BUT NONE SO FAR INDICATED IN METAR OBS. THE MARINE
LAYER IS PRESENTLY 2000-2400 FEET DEEP PER RECENT BODEGA
BAY...FORT ORD PROFILERS AND BAY AREA SODAR DATA.

VICINITY OF KSFO...BKN-OVC MVFR CIGS FORECAST TIL 19Z. WESTERLY
WINDS ARE LIKELY TO REMAIN UNDER 20 KNOTS TODAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS TIL 18Z FOLLOWED BY PARTIAL
CLEARING FOR THE AFTERNOON HOURS. PERSISTENCE FORECAST FOR THE
EVENING...STRATUS IS LIKELY TO RETURN EARLY.

&&

.MARINE...AS OF 08:53 AM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE FOR ZONES NORTH OF POINT
REYES.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...SF BAY NORTH OF THE BAY BRIDGE

&&

$$

PUBLIC FORECAST: RWW
AVIATION: CANEPA
MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 201612
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
912 AM PDT MON APR 20 2015

.SYNOPSIS...COOL CONDITIONS WILL PERSIST NEAR THE COAST TODAY WITH
WARM TEMPERATURES EXPECTED INLAND. TEMPERATURES COOL SLIGHTLY
REGION-WIDE BEGINNING TUESDAY AS A SERIES OF WEAK UPPER LEVEL
SYSTEMS PUSH ACROSS THE REGION. THESE WEAK WEATHER SYSTEMS WILL
PRODUCE A SLIGHT CHANCE OF SHOWERS AT TIMES TUESDAY THROUGH
THURSDAY...BUT MAINLY OVER THE INLAND MOUNTAINS.

&&

.DISCUSSION...AS OF 9:12 AM PDT MONDAY...DEEP MARINE LAYER IN
PLACE THIS MORNING TO AROUND 2500 FEET ALONG THE COAST WITH
STRATUS HAVING OVERSPREAD NEARLY ALL VALLEYS ACROSS THE DISTRICT
BELOW THIS ELEVATION. A WEAK UPPER LOW WEST OF LOS ANGELES WILL
KEEP THE MARINE LAYER DEEP WITH ONSHORE FLOW IN PLACE TODAY.
EXPECT FAIRLY SLOW BURN-OFF OF THE LOW CLOUDS TODAY GIVEN THE DEEP
LAYER WITH LITTLE OR NO CLEARING NEAR THE COAST AND SOME PARTS OF
THE BAY.

UPPER LOW OVER SOUTHERN CALIFORNIA WONT MOVE MUCH THROUGH WEDS
KEEPING CONDITIONS FAIRLY STATIC WITH A DEEP MARINE LAYER AND NEAR OR
BELOW NORMAL TEMPS. THIS FEATURE WILL HELP TO GENERATE AFTERNOON
SHOWERS AND T-STORMS OVER THE SIERRA AND OTHER HIGH MOUNTAINS OF
THE STATE BUT NOT EXPECTING ANY ACTIVITY OVER THE BAY AREA
HILLS...EXCEPTION BEING SOME LOCALIZED NIGHT AND MORNING DRIZZLE
DUE TO A DEEP MARINE LAYER.

MID AND LONG RANGE MODELS KEEP THE MAIN STORM TRACK JUST NORTH OF
THE BAY AREA. THE SYNOPTIC PATTERN LOOKS TO REMAIN FAIRLY ACTIVE
BUT AT THIS TIME IT LOOKS LIKE MOST RAINS WILL STAY ACROSS FAR
NORTHERN CALIFORNIA AND POINTS NORTHWARD.

&&

.PREV DISCUSSION...AS OF 4:37 AM PDT MONDAY...ONSHORE FLOW AND A
PERSISTENT MARINE LAYER GREATER THAN 2KFT DEEP HAS ALLOWED FOR LOW
CLOUDS TO ONCE AGAIN DEVELOP WELL INLAND INTO MOST VALLEY
LOCATIONS THIS MORNING. THIS HAS HELD OVERNIGHT TEMPERATURES IN
THE LOW/MID 50S REGION-WIDE. MEANWHILE...A WEAK MID/UPPER LEVEL
LOW PRESSURE SYSTEM CONTINUES TO DROP SOUTHWARD OFF OF THE CENTRAL
COAST AND WILL APPROACH THE SOUTHERN CALIFORNIA COAST DURING THE
NEXT 24 HOURS OR SO. AS THIS SYSTEM LINGERS OFF OF THE
COAST...WEATHER CONDITIONS TODAY WILL BE A NEAR REPEAT OF THOSE ON
SUNDAY. THUS...COOL TEMPERATURES NEAR THE COAST WHILE INLAND AREAS
ONCE AGAIN WARM INTO THE 70S AND LOWER 80S. IN ADDITION...THE
FORECAST MODELS KEEP THE BEST MID-LEVEL MOISTURE ASSOCIATED WITH
THIS SYSTEM WELL INLAND TODAY. WITH THAT...WILL MAINTAIN A DRY
FORECAST THROUGH THIS AFTERNOON/EVENING.

AS THE MARINE LAYER DEEPENS OVERNIGHT...PATCHY FOG AND DRIZZLE
WILL BE POSSIBLE ALONG THE COAST BY EARLY TUESDAY MORNING.
DAYTIME TEMPERATURES WILL FINALLY COOL INLAND THROUGH MIDWEEK AS
850MB CONDITIONS COOL AHEAD OF AN APPROACHING UPPER LEVEL TROUGH.
THE FORECAST MODELS CONTINUE TO STRUGGLE ON HOW MUCH MOISTURE
WILL BE ADVECTED INTO THE REGION WITH THIS SYSTEM...AND IF THE
ATMOSPHERE WILL BECOME UNSTABLE ENOUGH FOR SHOWERS/THUNDERSTORMS
TO DEVELOP OVER THE INLAND HILLS/MOUNTAINS. FOR NOW...WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORM OVER THE MOUNTAINS OF
SAN BENITO COUNTY FOR TUESDAY AFTERNOON/EVENING AND SHOWERS OVER
MUCH OF THE HIGHER TERRAIN ON WEDNESDAY. AS A BROAD MID/UPPER
LEVEL TROUGH REMAINS OVER MUCH OF THE WEST COAST THROUGH LATE
WEEK WITH WEAK DISTURBANCES MOVING ACROSS THE REGION...CANNOT
RULE OUT A FEW SHOWERS OVER THE INLAND HILLS/MOUNTAINS THROUGH
THURSDAY. THE MEDIUM RANGE MODELS NOW SHOW DRY CONDITIONS
RETURNING TO THE REGION FOR FRIDAY AS THE UPPER LEVEL TROUGH AXIS
SHIFTS INLAND. HAVING SAID ALL THAT...MOST LOCATIONS WILL SEE
LITTLE TO NO RAINFALL THROUGH LATE WEEK.

MUCH OF THE UPCOMING WEEKEND IS NOW FORECAST TO REMAIN DRY WITH
THE UPPER LEVEL STORM TRACK WELL TO THE NORTH. HOWEVER...WILL
CARRY A SLIGHT CHANCE OF PRECIPITATION OVER THE NORTH BAY SUNDAY
INTO MONDAY AS THE 12Z GFS PUSHES A SYSTEM INTO THE PACIFIC
NORTHWEST WITH TRAILING MOISTURE ALONG A FRONTAL BOUNDARY
DROPPING SOUTHWARD. MEANWHILE...THE CMC AND ECMWF MAINTAIN DRY
WEATHER CONDITIONS FOR LATE IN THE FORECAST PERIOD WITH WEAK
RIDING OVER CENTRAL CALIFORNIA. OVERALL...CHANCES FOR MEASURABLE
RAINFALL OVER THE REGION THROUGH THE END OF APRIL ARE LOOKING
MINIMAL AT BEST.

&&

.AVIATION...AS OF 5:21 AM PDT MONDAY...TODAY IS DAY 3 WITH
WIDESPREAD COASTAL STRATUS WITH A NOCTURNAL INLAND INTRUSION AS
SEEN ON SATELLITE RESULTING IN MVFR TO IFR CIGS AT AREA TERMINALS.
RECENT MODEL TRENDS HAVE SHOWN A DELAY IN THE LOW LEVEL COOLING
(850 MB PRESSURE LEVEL) ONCE EXPECTED TO ARRIVE AS SOON AS
TUESDAY...BUT NOW IT LOOKS LIKE IT`LL BE WEDNESDAY. THE MARINE
LAYER SHOULD HOLD TOGETHER FAIRLY WELL TODAY THROUGH TUESDAY
BEFORE ANY SIGNIFICANT WEAKENING MAY OCCUR MID TO LATE WEEK. THERE
MAY BE POCKETS OF LIGHT DRIZZLE AS A DEEPER MARINE LAYER
PERSISTS...BUT NONE SO FAR INDICATED IN METAR OBS. THE MARINE
LAYER IS PRESENTLY 2000-2400 FEET DEEP PER RECENT BODEGA
BAY...FORT ORD PROFILERS AND BAY AREA SODAR DATA.

VICINITY OF KSFO...BKN-OVC MVFR CIGS FORECAST TIL 19Z. WESTERLY
WINDS ARE LIKELY TO REMAIN UNDER 20 KNOTS TODAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS TIL 18Z FOLLOWED BY PARTIAL
CLEARING FOR THE AFTERNOON HOURS. PERSISTENCE FORECAST FOR THE
EVENING...STRATUS IS LIKELY TO RETURN EARLY.

&&

.MARINE...AS OF 08:53 AM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE FOR ZONES NORTH OF POINT
REYES.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...SF BAY NORTH OF THE BAY BRIDGE

&&

$$

PUBLIC FORECAST: RWW
AVIATION: CANEPA
MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
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000
FXUS66 KMTR 201612
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
912 AM PDT MON APR 20 2015

.SYNOPSIS...COOL CONDITIONS WILL PERSIST NEAR THE COAST TODAY WITH
WARM TEMPERATURES EXPECTED INLAND. TEMPERATURES COOL SLIGHTLY
REGION-WIDE BEGINNING TUESDAY AS A SERIES OF WEAK UPPER LEVEL
SYSTEMS PUSH ACROSS THE REGION. THESE WEAK WEATHER SYSTEMS WILL
PRODUCE A SLIGHT CHANCE OF SHOWERS AT TIMES TUESDAY THROUGH
THURSDAY...BUT MAINLY OVER THE INLAND MOUNTAINS.

&&

.DISCUSSION...AS OF 9:12 AM PDT MONDAY...DEEP MARINE LAYER IN
PLACE THIS MORNING TO AROUND 2500 FEET ALONG THE COAST WITH
STRATUS HAVING OVERSPREAD NEARLY ALL VALLEYS ACROSS THE DISTRICT
BELOW THIS ELEVATION. A WEAK UPPER LOW WEST OF LOS ANGELES WILL
KEEP THE MARINE LAYER DEEP WITH ONSHORE FLOW IN PLACE TODAY.
EXPECT FAIRLY SLOW BURN-OFF OF THE LOW CLOUDS TODAY GIVEN THE DEEP
LAYER WITH LITTLE OR NO CLEARING NEAR THE COAST AND SOME PARTS OF
THE BAY.

UPPER LOW OVER SOUTHERN CALIFORNIA WONT MOVE MUCH THROUGH WEDS
KEEPING CONDITIONS FAIRLY STATIC WITH A DEEP MARINE LAYER AND NEAR OR
BELOW NORMAL TEMPS. THIS FEATURE WILL HELP TO GENERATE AFTERNOON
SHOWERS AND T-STORMS OVER THE SIERRA AND OTHER HIGH MOUNTAINS OF
THE STATE BUT NOT EXPECTING ANY ACTIVITY OVER THE BAY AREA
HILLS...EXCEPTION BEING SOME LOCALIZED NIGHT AND MORNING DRIZZLE
DUE TO A DEEP MARINE LAYER.

MID AND LONG RANGE MODELS KEEP THE MAIN STORM TRACK JUST NORTH OF
THE BAY AREA. THE SYNOPTIC PATTERN LOOKS TO REMAIN FAIRLY ACTIVE
BUT AT THIS TIME IT LOOKS LIKE MOST RAINS WILL STAY ACROSS FAR
NORTHERN CALIFORNIA AND POINTS NORTHWARD.

&&

.PREV DISCUSSION...AS OF 4:37 AM PDT MONDAY...ONSHORE FLOW AND A
PERSISTENT MARINE LAYER GREATER THAN 2KFT DEEP HAS ALLOWED FOR LOW
CLOUDS TO ONCE AGAIN DEVELOP WELL INLAND INTO MOST VALLEY
LOCATIONS THIS MORNING. THIS HAS HELD OVERNIGHT TEMPERATURES IN
THE LOW/MID 50S REGION-WIDE. MEANWHILE...A WEAK MID/UPPER LEVEL
LOW PRESSURE SYSTEM CONTINUES TO DROP SOUTHWARD OFF OF THE CENTRAL
COAST AND WILL APPROACH THE SOUTHERN CALIFORNIA COAST DURING THE
NEXT 24 HOURS OR SO. AS THIS SYSTEM LINGERS OFF OF THE
COAST...WEATHER CONDITIONS TODAY WILL BE A NEAR REPEAT OF THOSE ON
SUNDAY. THUS...COOL TEMPERATURES NEAR THE COAST WHILE INLAND AREAS
ONCE AGAIN WARM INTO THE 70S AND LOWER 80S. IN ADDITION...THE
FORECAST MODELS KEEP THE BEST MID-LEVEL MOISTURE ASSOCIATED WITH
THIS SYSTEM WELL INLAND TODAY. WITH THAT...WILL MAINTAIN A DRY
FORECAST THROUGH THIS AFTERNOON/EVENING.

AS THE MARINE LAYER DEEPENS OVERNIGHT...PATCHY FOG AND DRIZZLE
WILL BE POSSIBLE ALONG THE COAST BY EARLY TUESDAY MORNING.
DAYTIME TEMPERATURES WILL FINALLY COOL INLAND THROUGH MIDWEEK AS
850MB CONDITIONS COOL AHEAD OF AN APPROACHING UPPER LEVEL TROUGH.
THE FORECAST MODELS CONTINUE TO STRUGGLE ON HOW MUCH MOISTURE
WILL BE ADVECTED INTO THE REGION WITH THIS SYSTEM...AND IF THE
ATMOSPHERE WILL BECOME UNSTABLE ENOUGH FOR SHOWERS/THUNDERSTORMS
TO DEVELOP OVER THE INLAND HILLS/MOUNTAINS. FOR NOW...WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORM OVER THE MOUNTAINS OF
SAN BENITO COUNTY FOR TUESDAY AFTERNOON/EVENING AND SHOWERS OVER
MUCH OF THE HIGHER TERRAIN ON WEDNESDAY. AS A BROAD MID/UPPER
LEVEL TROUGH REMAINS OVER MUCH OF THE WEST COAST THROUGH LATE
WEEK WITH WEAK DISTURBANCES MOVING ACROSS THE REGION...CANNOT
RULE OUT A FEW SHOWERS OVER THE INLAND HILLS/MOUNTAINS THROUGH
THURSDAY. THE MEDIUM RANGE MODELS NOW SHOW DRY CONDITIONS
RETURNING TO THE REGION FOR FRIDAY AS THE UPPER LEVEL TROUGH AXIS
SHIFTS INLAND. HAVING SAID ALL THAT...MOST LOCATIONS WILL SEE
LITTLE TO NO RAINFALL THROUGH LATE WEEK.

MUCH OF THE UPCOMING WEEKEND IS NOW FORECAST TO REMAIN DRY WITH
THE UPPER LEVEL STORM TRACK WELL TO THE NORTH. HOWEVER...WILL
CARRY A SLIGHT CHANCE OF PRECIPITATION OVER THE NORTH BAY SUNDAY
INTO MONDAY AS THE 12Z GFS PUSHES A SYSTEM INTO THE PACIFIC
NORTHWEST WITH TRAILING MOISTURE ALONG A FRONTAL BOUNDARY
DROPPING SOUTHWARD. MEANWHILE...THE CMC AND ECMWF MAINTAIN DRY
WEATHER CONDITIONS FOR LATE IN THE FORECAST PERIOD WITH WEAK
RIDING OVER CENTRAL CALIFORNIA. OVERALL...CHANCES FOR MEASURABLE
RAINFALL OVER THE REGION THROUGH THE END OF APRIL ARE LOOKING
MINIMAL AT BEST.

&&

.AVIATION...AS OF 5:21 AM PDT MONDAY...TODAY IS DAY 3 WITH
WIDESPREAD COASTAL STRATUS WITH A NOCTURNAL INLAND INTRUSION AS
SEEN ON SATELLITE RESULTING IN MVFR TO IFR CIGS AT AREA TERMINALS.
RECENT MODEL TRENDS HAVE SHOWN A DELAY IN THE LOW LEVEL COOLING
(850 MB PRESSURE LEVEL) ONCE EXPECTED TO ARRIVE AS SOON AS
TUESDAY...BUT NOW IT LOOKS LIKE IT`LL BE WEDNESDAY. THE MARINE
LAYER SHOULD HOLD TOGETHER FAIRLY WELL TODAY THROUGH TUESDAY
BEFORE ANY SIGNIFICANT WEAKENING MAY OCCUR MID TO LATE WEEK. THERE
MAY BE POCKETS OF LIGHT DRIZZLE AS A DEEPER MARINE LAYER
PERSISTS...BUT NONE SO FAR INDICATED IN METAR OBS. THE MARINE
LAYER IS PRESENTLY 2000-2400 FEET DEEP PER RECENT BODEGA
BAY...FORT ORD PROFILERS AND BAY AREA SODAR DATA.

VICINITY OF KSFO...BKN-OVC MVFR CIGS FORECAST TIL 19Z. WESTERLY
WINDS ARE LIKELY TO REMAIN UNDER 20 KNOTS TODAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS TIL 18Z FOLLOWED BY PARTIAL
CLEARING FOR THE AFTERNOON HOURS. PERSISTENCE FORECAST FOR THE
EVENING...STRATUS IS LIKELY TO RETURN EARLY.

&&

.MARINE...AS OF 08:53 AM PDT MONDAY...NORTHWESTERLY WINDS WILL BE
ON THE INCREASE STARTING TOMORROW AS HIGH PRESSURE BUILDS IN FROM
THE NORTH. THE BIGGEST IMPACT WILL BE FOR ZONES NORTH OF POINT
REYES.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...SF BAY NORTH OF THE BAY BRIDGE

&&

$$

PUBLIC FORECAST: RWW
AVIATION: CANEPA
MARINE: BELL

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 201234
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
534 AM PDT MON APR 20 2015

.SYNOPSIS...COOL CONDITIONS WILL PERSIST NEAR THE COAST TODAY WITH
WARM TEMPERATURES EXPECTED INLAND. TEMPERATURES COOL SLIGHTLY
REGION-WIDE BEGINNING TUESDAY AS A SERIES OF WEAK UPPER LEVEL
SYSTEMS PUSH ACROSS THE REGION. THESE WEAK WEATHER SYSTEMS WILL
PRODUCE A SLIGHT CHANCE OF SHOWERS AT TIMES TUESDAY THROUGH
THURSDAY...BUT MAINLY OVER THE INLAND MOUNTAINS.

&&

.DISCUSSION...AS OF 04:37 AM PDT MONDAY...ONSHORE FLOW AND A
PERSISTENT MARINE LAYER GREATER THAN 2KFT DEEP HAS ALLOWED FOR
LOW CLOUDS TO ONCE AGAIN DEVELOP WELL INLAND INTO MOST VALLEY
LOCATIONS THIS MORNING. THIS HAS HELD OVERNIGHT TEMPERATURES IN
THE LOW/MID 50S REGION-WIDE. MEANWHILE...A WEAK MID/UPPER LEVEL
LOW PRESSURE SYSTEM CONTINUES TO DROP SOUTHWARD OFF OF THE
CENTRAL COAST AND WILL APPROACH THE SOUTHERN CALIFORNIA COAST
DURING THE NEXT 24 HOURS OR SO. AS THIS SYSTEM LINGERS OFF OF THE
COAST...WEATHER CONDITIONS TODAY WILL BE A NEAR REPEAT OF THOSE
ON SUNDAY. THUS...COOL TEMPERATURES NEAR THE COAST WHILE INLAND
AREAS ONCE AGAIN WARM INTO THE 70S AND LOWER 80S. IN
ADDITION...THE FORECAST MODELS KEEP THE BEST MID-LEVEL MOISTURE
ASSOCIATED WITH THIS SYSTEM WELL INLAND TODAY. WITH THAT...WILL
MAINTAIN A DRY FORECAST THROUGH THIS AFTERNOON/EVENING.

AS THE MARINE LAYER DEEPENS OVERNIGHT...PATCHY FOG AND DRIZZLE
WILL BE POSSIBLE ALONG THE COAST BY EARLY TUESDAY MORNING.
DAYTIME TEMPERATURES WILL FINALLY COOL INLAND THROUGH MIDWEEK AS
850MB CONDITIONS COOL AHEAD OF AN APPROACHING UPPER LEVEL TROUGH.
THE FORECAST MODELS CONTINUE TO STRUGGLE ON HOW MUCH MOISTURE
WILL BE ADVECTED INTO THE REGION WITH THIS SYSTEM...AND IF THE
ATMOSPHERE WILL BECOME UNSTABLE ENOUGH FOR SHOWERS/THUNDERSTORMS
TO DEVELOP OVER THE INLAND HILLS/MOUNTAINS. FOR NOW...WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORM OVER THE MOUNTAINS OF
SAN BENITO COUNTY FOR TUESDAY AFTERNOON/EVENING AND SHOWERS OVER
MUCH OF THE HIGHER TERRAIN ON WEDNESDAY. AS A BROAD MID/UPPER
LEVEL TROUGH REMAINS OVER MUCH OF THE WEST COAST THROUGH LATE
WEEK WITH WEAK DISTURBANCES MOVING ACROSS THE REGION...CANNOT
RULE OUT A FEW SHOWERS OVER THE INLAND HILLS/MOUNTAINS THROUGH
THURSDAY. THE MEDIUM RANGE MODELS NOW SHOW DRY CONDITIONS
RETURNING TO THE REGION FOR FRIDAY AS THE UPPER LEVEL TROUGH AXIS
SHIFTS INLAND. HAVING SAID ALL THAT...MOST LOCATIONS WILL SEE
LITTLE TO NO RAINFALL THROUGH LATE WEEK.

MUCH OF THE UPCOMING WEEKEND IS NOW FORECAST TO REMAIN DRY WITH
THE UPPER LEVEL STORM TRACK WELL TO THE NORTH. HOWEVER...WILL
CARRY A SLIGHT CHANCE OF PRECIPITATION OVER THE NORTH BAY SUNDAY
INTO MONDAY AS THE 12Z GFS PUSHES A SYSTEM INTO THE PACIFIC
NORTHWEST WITH TRAILING MOISTURE ALONG A FRONTAL BOUNDARY
DROPPING SOUTHWARD. MEANWHILE...THE CMC AND ECMWF MAINTAIN DRY
WEATHER CONDITIONS FOR LATE IN THE FORECAST PERIOD WITH WEAK
RIDING OVER CENTRAL CALIFORNIA. OVERALL...CHANCES FOR MEASURABLE
RAINFALL OVER THE REGION THROUGH THE END OF APRIL ARE LOOKING
MINIMAL AT BEST.

&&

.AVIATION...AS OF 5:21 AM PDT MONDAY...TODAY IS DAY 3 WITH
WIDESPREAD COASTAL STRATUS WITH A NOCTURNAL INLAND INTRUSION AS
SEEN ON SATELLITE RESULTING IN MVFR TO IFR CIGS AT AREA TERMINALS.
RECENT MODEL TRENDS HAVE SHOWN A DELAY IN THE LOW LEVEL COOLING
(850 MB PRESSURE LEVEL) ONCE EXPECTED TO ARRIVE AS SOON AS
TUESDAY...BUT NOW IT LOOKS LIKE IT`LL BE WEDNESDAY. THE MARINE
LAYER SHOULD HOLD TOGETHER FAIRLY WELL TODAY THROUGH TUESDAY
BEFORE ANY SIGNIFICANT WEAKENING MAY OCCUR MID TO LATE WEEK. THERE
MAY BE POCKETS OF LIGHT DRIZZLE AS A DEEPER MARINE LAYER
PERSISTS...BUT NONE SO FAR INDICATED IN METAR OBS. THE MARINE
LAYER IS PRESENTLY 2000-2400 FEET DEEP PER RECENT BODEGA
BAY...FORT ORD PROFILERS AND BAY AREA SODAR DATA.

VICINITY OF KSFO...BKN-OVC MVFR CIGS FORECAST TIL 19Z. WESTERLY
WINDS ARE LIKELY TO REMAIN UNDER 20 KNOTS TODAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS TIL 18Z FOLLOWED BY PARTIAL
CLEARING FOR THE AFTERNOON HOURS. PERSISTENCE FORECAST FOR THE
EVENING...STRATUS IS LIKELY TO RETURN EARLY.

&&

.MARINE...AS OF 4:09 AM PDT MONDAY...AN UPPER LEVEL LOW PRESSURE
AREA LOCATED 300 MILES SOUTHWEST OF POINT CONCEPTION WILL CONTINUE
TO MOVE SOUTHEAST AND REACH SOUTHERN CALIFORNIA BY EARLY TUESDAY
MORNING. ANOTHER UPPER LEVEL LOW OVER THE EASTERN PACIFIC WILL
REACH THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA BY TUESDAY
NIGHT INTO WEDNESDAY. THIS MAY TEND TO INCREASE NORTHWESTERLY
WINDS OVER THE NORTHERN OUTER COASTAL WATERS BY TUESDAY NIGHT BUT
THERE IS SOME UNCERTAINTY REGARDING WIND STRENGTH AT THIS TIME.

WANTED TO ADD TO THIS THAT RECENT NAM MODEL FORECASTS THROUGH THE
WEEKEND HAVE INITIALIZED FAIRLY WELL ON EACH RUN BUT HAVE HAD SOME
TROUBLE FORECASTING THE NORTHERLY & SOUTHERLY GRADIENTS OVER THE
COASTAL WATERS WITHIN DAY 1. BASED ON THIS...AM HAVING SOME DOUBT
THAT NW WINDS OVER THE NORTHERN OUTER WATERS WILL BECOME AS STRONG
AS EARLY AS INDICATED IN THE 4/20 06Z NAM RUN. SMALL CRAFT WINDS
ARE POSSIBLE BY WEDNESDAY NW WATERS BUT GALE GUSTS WILL PROBABLY
STAY TO THE NORTH OF THE NORTHERN MARINE ZONES. 12Z NAM MAY SOLIDIFY
THIS ONE WAY OR THE OTHER. AT ANY RATE WILL PASS ALONG THOUGHTS TO
THE DAY SHIFT.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...SF BAY NORTH OF THE BAY BRIDGE

&&

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 201234
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
534 AM PDT MON APR 20 2015

.SYNOPSIS...COOL CONDITIONS WILL PERSIST NEAR THE COAST TODAY WITH
WARM TEMPERATURES EXPECTED INLAND. TEMPERATURES COOL SLIGHTLY
REGION-WIDE BEGINNING TUESDAY AS A SERIES OF WEAK UPPER LEVEL
SYSTEMS PUSH ACROSS THE REGION. THESE WEAK WEATHER SYSTEMS WILL
PRODUCE A SLIGHT CHANCE OF SHOWERS AT TIMES TUESDAY THROUGH
THURSDAY...BUT MAINLY OVER THE INLAND MOUNTAINS.

&&

.DISCUSSION...AS OF 04:37 AM PDT MONDAY...ONSHORE FLOW AND A
PERSISTENT MARINE LAYER GREATER THAN 2KFT DEEP HAS ALLOWED FOR
LOW CLOUDS TO ONCE AGAIN DEVELOP WELL INLAND INTO MOST VALLEY
LOCATIONS THIS MORNING. THIS HAS HELD OVERNIGHT TEMPERATURES IN
THE LOW/MID 50S REGION-WIDE. MEANWHILE...A WEAK MID/UPPER LEVEL
LOW PRESSURE SYSTEM CONTINUES TO DROP SOUTHWARD OFF OF THE
CENTRAL COAST AND WILL APPROACH THE SOUTHERN CALIFORNIA COAST
DURING THE NEXT 24 HOURS OR SO. AS THIS SYSTEM LINGERS OFF OF THE
COAST...WEATHER CONDITIONS TODAY WILL BE A NEAR REPEAT OF THOSE
ON SUNDAY. THUS...COOL TEMPERATURES NEAR THE COAST WHILE INLAND
AREAS ONCE AGAIN WARM INTO THE 70S AND LOWER 80S. IN
ADDITION...THE FORECAST MODELS KEEP THE BEST MID-LEVEL MOISTURE
ASSOCIATED WITH THIS SYSTEM WELL INLAND TODAY. WITH THAT...WILL
MAINTAIN A DRY FORECAST THROUGH THIS AFTERNOON/EVENING.

AS THE MARINE LAYER DEEPENS OVERNIGHT...PATCHY FOG AND DRIZZLE
WILL BE POSSIBLE ALONG THE COAST BY EARLY TUESDAY MORNING.
DAYTIME TEMPERATURES WILL FINALLY COOL INLAND THROUGH MIDWEEK AS
850MB CONDITIONS COOL AHEAD OF AN APPROACHING UPPER LEVEL TROUGH.
THE FORECAST MODELS CONTINUE TO STRUGGLE ON HOW MUCH MOISTURE
WILL BE ADVECTED INTO THE REGION WITH THIS SYSTEM...AND IF THE
ATMOSPHERE WILL BECOME UNSTABLE ENOUGH FOR SHOWERS/THUNDERSTORMS
TO DEVELOP OVER THE INLAND HILLS/MOUNTAINS. FOR NOW...WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORM OVER THE MOUNTAINS OF
SAN BENITO COUNTY FOR TUESDAY AFTERNOON/EVENING AND SHOWERS OVER
MUCH OF THE HIGHER TERRAIN ON WEDNESDAY. AS A BROAD MID/UPPER
LEVEL TROUGH REMAINS OVER MUCH OF THE WEST COAST THROUGH LATE
WEEK WITH WEAK DISTURBANCES MOVING ACROSS THE REGION...CANNOT
RULE OUT A FEW SHOWERS OVER THE INLAND HILLS/MOUNTAINS THROUGH
THURSDAY. THE MEDIUM RANGE MODELS NOW SHOW DRY CONDITIONS
RETURNING TO THE REGION FOR FRIDAY AS THE UPPER LEVEL TROUGH AXIS
SHIFTS INLAND. HAVING SAID ALL THAT...MOST LOCATIONS WILL SEE
LITTLE TO NO RAINFALL THROUGH LATE WEEK.

MUCH OF THE UPCOMING WEEKEND IS NOW FORECAST TO REMAIN DRY WITH
THE UPPER LEVEL STORM TRACK WELL TO THE NORTH. HOWEVER...WILL
CARRY A SLIGHT CHANCE OF PRECIPITATION OVER THE NORTH BAY SUNDAY
INTO MONDAY AS THE 12Z GFS PUSHES A SYSTEM INTO THE PACIFIC
NORTHWEST WITH TRAILING MOISTURE ALONG A FRONTAL BOUNDARY
DROPPING SOUTHWARD. MEANWHILE...THE CMC AND ECMWF MAINTAIN DRY
WEATHER CONDITIONS FOR LATE IN THE FORECAST PERIOD WITH WEAK
RIDING OVER CENTRAL CALIFORNIA. OVERALL...CHANCES FOR MEASURABLE
RAINFALL OVER THE REGION THROUGH THE END OF APRIL ARE LOOKING
MINIMAL AT BEST.

&&

.AVIATION...AS OF 5:21 AM PDT MONDAY...TODAY IS DAY 3 WITH
WIDESPREAD COASTAL STRATUS WITH A NOCTURNAL INLAND INTRUSION AS
SEEN ON SATELLITE RESULTING IN MVFR TO IFR CIGS AT AREA TERMINALS.
RECENT MODEL TRENDS HAVE SHOWN A DELAY IN THE LOW LEVEL COOLING
(850 MB PRESSURE LEVEL) ONCE EXPECTED TO ARRIVE AS SOON AS
TUESDAY...BUT NOW IT LOOKS LIKE IT`LL BE WEDNESDAY. THE MARINE
LAYER SHOULD HOLD TOGETHER FAIRLY WELL TODAY THROUGH TUESDAY
BEFORE ANY SIGNIFICANT WEAKENING MAY OCCUR MID TO LATE WEEK. THERE
MAY BE POCKETS OF LIGHT DRIZZLE AS A DEEPER MARINE LAYER
PERSISTS...BUT NONE SO FAR INDICATED IN METAR OBS. THE MARINE
LAYER IS PRESENTLY 2000-2400 FEET DEEP PER RECENT BODEGA
BAY...FORT ORD PROFILERS AND BAY AREA SODAR DATA.

VICINITY OF KSFO...BKN-OVC MVFR CIGS FORECAST TIL 19Z. WESTERLY
WINDS ARE LIKELY TO REMAIN UNDER 20 KNOTS TODAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS TIL 18Z FOLLOWED BY PARTIAL
CLEARING FOR THE AFTERNOON HOURS. PERSISTENCE FORECAST FOR THE
EVENING...STRATUS IS LIKELY TO RETURN EARLY.

&&

.MARINE...AS OF 4:09 AM PDT MONDAY...AN UPPER LEVEL LOW PRESSURE
AREA LOCATED 300 MILES SOUTHWEST OF POINT CONCEPTION WILL CONTINUE
TO MOVE SOUTHEAST AND REACH SOUTHERN CALIFORNIA BY EARLY TUESDAY
MORNING. ANOTHER UPPER LEVEL LOW OVER THE EASTERN PACIFIC WILL
REACH THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA BY TUESDAY
NIGHT INTO WEDNESDAY. THIS MAY TEND TO INCREASE NORTHWESTERLY
WINDS OVER THE NORTHERN OUTER COASTAL WATERS BY TUESDAY NIGHT BUT
THERE IS SOME UNCERTAINTY REGARDING WIND STRENGTH AT THIS TIME.

WANTED TO ADD TO THIS THAT RECENT NAM MODEL FORECASTS THROUGH THE
WEEKEND HAVE INITIALIZED FAIRLY WELL ON EACH RUN BUT HAVE HAD SOME
TROUBLE FORECASTING THE NORTHERLY & SOUTHERLY GRADIENTS OVER THE
COASTAL WATERS WITHIN DAY 1. BASED ON THIS...AM HAVING SOME DOUBT
THAT NW WINDS OVER THE NORTHERN OUTER WATERS WILL BECOME AS STRONG
AS EARLY AS INDICATED IN THE 4/20 06Z NAM RUN. SMALL CRAFT WINDS
ARE POSSIBLE BY WEDNESDAY NW WATERS BUT GALE GUSTS WILL PROBABLY
STAY TO THE NORTH OF THE NORTHERN MARINE ZONES. 12Z NAM MAY SOLIDIFY
THIS ONE WAY OR THE OTHER. AT ANY RATE WILL PASS ALONG THOUGHTS TO
THE DAY SHIFT.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...SF BAY NORTH OF THE BAY BRIDGE

&&

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 201234
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
534 AM PDT MON APR 20 2015

.SYNOPSIS...COOL CONDITIONS WILL PERSIST NEAR THE COAST TODAY WITH
WARM TEMPERATURES EXPECTED INLAND. TEMPERATURES COOL SLIGHTLY
REGION-WIDE BEGINNING TUESDAY AS A SERIES OF WEAK UPPER LEVEL
SYSTEMS PUSH ACROSS THE REGION. THESE WEAK WEATHER SYSTEMS WILL
PRODUCE A SLIGHT CHANCE OF SHOWERS AT TIMES TUESDAY THROUGH
THURSDAY...BUT MAINLY OVER THE INLAND MOUNTAINS.

&&

.DISCUSSION...AS OF 04:37 AM PDT MONDAY...ONSHORE FLOW AND A
PERSISTENT MARINE LAYER GREATER THAN 2KFT DEEP HAS ALLOWED FOR
LOW CLOUDS TO ONCE AGAIN DEVELOP WELL INLAND INTO MOST VALLEY
LOCATIONS THIS MORNING. THIS HAS HELD OVERNIGHT TEMPERATURES IN
THE LOW/MID 50S REGION-WIDE. MEANWHILE...A WEAK MID/UPPER LEVEL
LOW PRESSURE SYSTEM CONTINUES TO DROP SOUTHWARD OFF OF THE
CENTRAL COAST AND WILL APPROACH THE SOUTHERN CALIFORNIA COAST
DURING THE NEXT 24 HOURS OR SO. AS THIS SYSTEM LINGERS OFF OF THE
COAST...WEATHER CONDITIONS TODAY WILL BE A NEAR REPEAT OF THOSE
ON SUNDAY. THUS...COOL TEMPERATURES NEAR THE COAST WHILE INLAND
AREAS ONCE AGAIN WARM INTO THE 70S AND LOWER 80S. IN
ADDITION...THE FORECAST MODELS KEEP THE BEST MID-LEVEL MOISTURE
ASSOCIATED WITH THIS SYSTEM WELL INLAND TODAY. WITH THAT...WILL
MAINTAIN A DRY FORECAST THROUGH THIS AFTERNOON/EVENING.

AS THE MARINE LAYER DEEPENS OVERNIGHT...PATCHY FOG AND DRIZZLE
WILL BE POSSIBLE ALONG THE COAST BY EARLY TUESDAY MORNING.
DAYTIME TEMPERATURES WILL FINALLY COOL INLAND THROUGH MIDWEEK AS
850MB CONDITIONS COOL AHEAD OF AN APPROACHING UPPER LEVEL TROUGH.
THE FORECAST MODELS CONTINUE TO STRUGGLE ON HOW MUCH MOISTURE
WILL BE ADVECTED INTO THE REGION WITH THIS SYSTEM...AND IF THE
ATMOSPHERE WILL BECOME UNSTABLE ENOUGH FOR SHOWERS/THUNDERSTORMS
TO DEVELOP OVER THE INLAND HILLS/MOUNTAINS. FOR NOW...WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORM OVER THE MOUNTAINS OF
SAN BENITO COUNTY FOR TUESDAY AFTERNOON/EVENING AND SHOWERS OVER
MUCH OF THE HIGHER TERRAIN ON WEDNESDAY. AS A BROAD MID/UPPER
LEVEL TROUGH REMAINS OVER MUCH OF THE WEST COAST THROUGH LATE
WEEK WITH WEAK DISTURBANCES MOVING ACROSS THE REGION...CANNOT
RULE OUT A FEW SHOWERS OVER THE INLAND HILLS/MOUNTAINS THROUGH
THURSDAY. THE MEDIUM RANGE MODELS NOW SHOW DRY CONDITIONS
RETURNING TO THE REGION FOR FRIDAY AS THE UPPER LEVEL TROUGH AXIS
SHIFTS INLAND. HAVING SAID ALL THAT...MOST LOCATIONS WILL SEE
LITTLE TO NO RAINFALL THROUGH LATE WEEK.

MUCH OF THE UPCOMING WEEKEND IS NOW FORECAST TO REMAIN DRY WITH
THE UPPER LEVEL STORM TRACK WELL TO THE NORTH. HOWEVER...WILL
CARRY A SLIGHT CHANCE OF PRECIPITATION OVER THE NORTH BAY SUNDAY
INTO MONDAY AS THE 12Z GFS PUSHES A SYSTEM INTO THE PACIFIC
NORTHWEST WITH TRAILING MOISTURE ALONG A FRONTAL BOUNDARY
DROPPING SOUTHWARD. MEANWHILE...THE CMC AND ECMWF MAINTAIN DRY
WEATHER CONDITIONS FOR LATE IN THE FORECAST PERIOD WITH WEAK
RIDING OVER CENTRAL CALIFORNIA. OVERALL...CHANCES FOR MEASURABLE
RAINFALL OVER THE REGION THROUGH THE END OF APRIL ARE LOOKING
MINIMAL AT BEST.

&&

.AVIATION...AS OF 5:21 AM PDT MONDAY...TODAY IS DAY 3 WITH
WIDESPREAD COASTAL STRATUS WITH A NOCTURNAL INLAND INTRUSION AS
SEEN ON SATELLITE RESULTING IN MVFR TO IFR CIGS AT AREA TERMINALS.
RECENT MODEL TRENDS HAVE SHOWN A DELAY IN THE LOW LEVEL COOLING
(850 MB PRESSURE LEVEL) ONCE EXPECTED TO ARRIVE AS SOON AS
TUESDAY...BUT NOW IT LOOKS LIKE IT`LL BE WEDNESDAY. THE MARINE
LAYER SHOULD HOLD TOGETHER FAIRLY WELL TODAY THROUGH TUESDAY
BEFORE ANY SIGNIFICANT WEAKENING MAY OCCUR MID TO LATE WEEK. THERE
MAY BE POCKETS OF LIGHT DRIZZLE AS A DEEPER MARINE LAYER
PERSISTS...BUT NONE SO FAR INDICATED IN METAR OBS. THE MARINE
LAYER IS PRESENTLY 2000-2400 FEET DEEP PER RECENT BODEGA
BAY...FORT ORD PROFILERS AND BAY AREA SODAR DATA.

VICINITY OF KSFO...BKN-OVC MVFR CIGS FORECAST TIL 19Z. WESTERLY
WINDS ARE LIKELY TO REMAIN UNDER 20 KNOTS TODAY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS TIL 18Z FOLLOWED BY PARTIAL
CLEARING FOR THE AFTERNOON HOURS. PERSISTENCE FORECAST FOR THE
EVENING...STRATUS IS LIKELY TO RETURN EARLY.

&&

.MARINE...AS OF 4:09 AM PDT MONDAY...AN UPPER LEVEL LOW PRESSURE
AREA LOCATED 300 MILES SOUTHWEST OF POINT CONCEPTION WILL CONTINUE
TO MOVE SOUTHEAST AND REACH SOUTHERN CALIFORNIA BY EARLY TUESDAY
MORNING. ANOTHER UPPER LEVEL LOW OVER THE EASTERN PACIFIC WILL
REACH THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA BY TUESDAY
NIGHT INTO WEDNESDAY. THIS MAY TEND TO INCREASE NORTHWESTERLY
WINDS OVER THE NORTHERN OUTER COASTAL WATERS BY TUESDAY NIGHT BUT
THERE IS SOME UNCERTAINTY REGARDING WIND STRENGTH AT THIS TIME.

WANTED TO ADD TO THIS THAT RECENT NAM MODEL FORECASTS THROUGH THE
WEEKEND HAVE INITIALIZED FAIRLY WELL ON EACH RUN BUT HAVE HAD SOME
TROUBLE FORECASTING THE NORTHERLY & SOUTHERLY GRADIENTS OVER THE
COASTAL WATERS WITHIN DAY 1. BASED ON THIS...AM HAVING SOME DOUBT
THAT NW WINDS OVER THE NORTHERN OUTER WATERS WILL BECOME AS STRONG
AS EARLY AS INDICATED IN THE 4/20 06Z NAM RUN. SMALL CRAFT WINDS
ARE POSSIBLE BY WEDNESDAY NW WATERS BUT GALE GUSTS WILL PROBABLY
STAY TO THE NORTH OF THE NORTHERN MARINE ZONES. 12Z NAM MAY SOLIDIFY
THIS ONE WAY OR THE OTHER. AT ANY RATE WILL PASS ALONG THOUGHTS TO
THE DAY SHIFT.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...SF BAY NORTH OF THE BAY BRIDGE

&&

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 201139
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
439 AM PDT MON APR 20 2015

.SYNOPSIS...COOL CONDITIONS WILL PERSIST NEAR THE COAST TODAY WITH
WARM TEMPERATURES EXPECTED INLAND. TEMPERATURES COOL SLIGHTLY
REGION-WIDE BEGINNING TUESDAY AS A SERIES OF WEAK UPPER LEVEL
SYSTEMS PUSH ACROSS THE REGION. THESE WEAK WEATHER SYSTEMS WILL
PRODUCE A SLIGHT CHANCE OF SHOWERS AT TIMES TUESDAY THROUGH
THURSDAY...BUT MAINLY OVER THE INLAND MOUNTAINS.

&&

.DISCUSSION...AS OF 04:37 AM PDT MONDAY...ONSHORE FLOW AND A
PERSISTENT MARINE LAYER GREATER THAN 2KFT DEEP HAS ALLOWED FOR
LOW CLOUDS TO ONCE AGAIN DEVELOP WELL INLAND INTO MOST VALLEY
LOCATIONS THIS MORNING. THIS HAS HELD OVERNIGHT TEMPERATURES IN
THE LOW/MID 50S REGION-WIDE. MEANWHILE...A WEAK MID/UPPER LEVEL
LOW PRESSURE SYSTEM CONTINUES TO DROP SOUTHWARD OFF OF THE
CENTRAL COAST AND WILL APPROACH THE SOUTHERN CALIFORNIA COAST
DURING THE NEXT 24 HOURS OR SO. AS THIS SYSTEM LINGERS OFF OF THE
COAST...WEATHER CONDITIONS TODAY WILL BE A NEAR REPEAT OF THOSE
ON SUNDAY. THUS...COOL TEMPERATURES NEAR THE COAST WHILE INLAND
AREAS ONCE AGAIN WARM INTO THE 70S AND LOWER 80S. IN
ADDITION...THE FORECAST MODELS KEEP THE BEST MID-LEVEL MOISTURE
ASSOCIATED WITH THIS SYSTEM WELL INLAND TODAY. WITH THAT...WILL
MAINTAIN A DRY FORECAST THROUGH THIS AFTERNOON/EVENING.

AS THE MARINE LAYER DEEPENS OVERNIGHT...PATCHY FOG AND DRIZZLE
WILL BE POSSIBLE ALONG THE COAST BY EARLY TUESDAY MORNING.
DAYTIME TEMPERATURES WILL FINALLY COOL INLAND THROUGH MIDWEEK AS
850MB CONDITIONS COOL AHEAD OF AN APPROACHING UPPER LEVEL TROUGH.
THE FORECAST MODELS CONTINUE TO STRUGGLE ON HOW MUCH MOISTURE
WILL BE ADVECTED INTO THE REGION WITH THIS SYSTEM...AND IF THE
ATMOSPHERE WILL BECOME UNSTABLE ENOUGH FOR SHOWERS/THUNDERSTORMS
TO DEVELOP OVER THE INLAND HILLS/MOUNTAINS. FOR NOW...WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORM OVER THE MOUNTAINS OF
SAN BENITO COUNTY FOR TUESDAY AFTERNOON/EVENING AND SHOWERS OVER
MUCH OF THE HIGHER TERRAIN ON WEDNESDAY. AS A BROAD MID/UPPER
LEVEL TROUGH REMAINS OVER MUCH OF THE WEST COAST THROUGH LATE
WEEK WITH WEAK DISTURBANCES MOVING ACROSS THE REGION...CANNOT
RULE OUT A FEW SHOWERS OVER THE INLAND HILLS/MOUNTAINS THROUGH
THURSDAY. THE MEDIUM RANGE MODELS NOW SHOW DRY CONDITIONS
RETURNING TO THE REGION FOR FRIDAY AS THE UPPER LEVEL TROUGH AXIS
SHIFTS INLAND. HAVING SAID ALL THAT...MOST LOCATIONS WILL SEE
LITTLE TO NO RAINFALL THROUGH LATE WEEK.

MUCH OF THE UPCOMING WEEKEND IS NOW FORECAST TO REMAIN DRY WITH
THE UPPER LEVEL STORM TRACK WELL TO THE NORTH. HOWEVER...WILL
CARRY A SLIGHT CHANCE OF PRECIPITATION OVER THE NORTH BAY SUNDAY
INTO MONDAY AS THE 12Z GFS PUSHES A SYSTEM INTO THE PACIFIC
NORTHWEST WITH TRAILING MOISTURE ALONG A FRONTAL BOUNDARY
DROPPING SOUTHWARD. MEANWHILE...THE CMC AND ECMWF MAINTAIN DRY
WEATHER CONDITIONS FOR LATE IN THE FORECAST PERIOD WITH WEAK
RIDING OVER CENTRAL CALIFORNIA. OVERALL...CHANCES FOR MEASURABLE
RAINFALL OVER THE REGION THROUGH THE END OF APRIL ARE LOOKING
MINIMAL AT BEST.

&&

.AVIATION...AS OF 11:00 PM PDT SUNDAY... WIDESPREAD STRATUS
INTRUSION TONIGHT WITH MVFR/IFR CIGS. THERMAL TROUGH BREAKDOWN
BETWEEN 01-02Z ALLOWED FOR A RAPID INTRUSION ONSHORE EARLIER THIS
EVENING. ALL TAF SITES ARE EXPECTED TO BE UNDER STRATUS DECK
THROUGH THE NIGHT AND INTO EARLY TOMORROW MORNING. CEILOMETER DATA
RANGING FROM OVC005 IN THE NORTH BAY TO BKN013 IN THE SOUTH BAY.
CIGS ARE LIKELY TO DESCEND INTO IFR RANGE FOR MANY TAF SITES
OVERNIGHT WITH SOME LOCATIONS SEEING POSSIBLE REDUCTION IN VISBY
BY EARLY MORNING.

VICINITY OF KSFO... STRATUS HAS BEEN FUNNELING THROUGH THE SAN
BRUNO GAP AND GOLDEN GATE REGIONS ON A DUE EAST TRAJECTORY. AS A
RESULT...LOW CIGS HAVE YET TO DIRECTLY IMPACT KSFO. LATEST FOG
PRODUCT SHOWS STRATUS SPREADING NORTHWARD FROM THE SOUTH BAY AND
WILL LIKELY REACH KSFO WITHIN THE NEXT TWO HOURS. KSQL LIKELY
WITHIN THE NEXT HOUR.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CIGS MVFR DETERIORATING TO IFR
OVERNIGHT. SLIGHT RISK OF LIFR VISBYS AROUND SUNRISE.

&&

.MARINE...AS OF 04:37 AM PDT MONDAY...AN UPPER LEVEL LOW PRESSURE
AREA LOCATED 300 MILES SOUTHWEST OF POINT CONCEPTION WILL CONTINUE
TO MOVE SOUTHEAST AND REACH SOUTHERN CALIFORNIA BY EARLY TUESDAY
MORNING. ANOTHER UPPER LEVEL LOW OVER THE EASTERN PACIFIC WILL
REACH THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA BY TUESDAY
NIGHT INTO WEDNESDAY. THIS MAY TEND TO INCREASE NORTHWESTERLY
WINDS OVER THE NORTHERN OUTER COASTAL WATERS BY TUESDAY NIGHT BUT
THERE IS SOME UNCERTAINTY REGARDING WIND STRENGTH AT THIS TIME.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...SF BAY NORTH OF THE BAY BRIDGE

&&

$$

PUBLIC FORECAST: RGASS
AVIATION: DRP
MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 201139
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
439 AM PDT MON APR 20 2015

.SYNOPSIS...COOL CONDITIONS WILL PERSIST NEAR THE COAST TODAY WITH
WARM TEMPERATURES EXPECTED INLAND. TEMPERATURES COOL SLIGHTLY
REGION-WIDE BEGINNING TUESDAY AS A SERIES OF WEAK UPPER LEVEL
SYSTEMS PUSH ACROSS THE REGION. THESE WEAK WEATHER SYSTEMS WILL
PRODUCE A SLIGHT CHANCE OF SHOWERS AT TIMES TUESDAY THROUGH
THURSDAY...BUT MAINLY OVER THE INLAND MOUNTAINS.

&&

.DISCUSSION...AS OF 04:37 AM PDT MONDAY...ONSHORE FLOW AND A
PERSISTENT MARINE LAYER GREATER THAN 2KFT DEEP HAS ALLOWED FOR
LOW CLOUDS TO ONCE AGAIN DEVELOP WELL INLAND INTO MOST VALLEY
LOCATIONS THIS MORNING. THIS HAS HELD OVERNIGHT TEMPERATURES IN
THE LOW/MID 50S REGION-WIDE. MEANWHILE...A WEAK MID/UPPER LEVEL
LOW PRESSURE SYSTEM CONTINUES TO DROP SOUTHWARD OFF OF THE
CENTRAL COAST AND WILL APPROACH THE SOUTHERN CALIFORNIA COAST
DURING THE NEXT 24 HOURS OR SO. AS THIS SYSTEM LINGERS OFF OF THE
COAST...WEATHER CONDITIONS TODAY WILL BE A NEAR REPEAT OF THOSE
ON SUNDAY. THUS...COOL TEMPERATURES NEAR THE COAST WHILE INLAND
AREAS ONCE AGAIN WARM INTO THE 70S AND LOWER 80S. IN
ADDITION...THE FORECAST MODELS KEEP THE BEST MID-LEVEL MOISTURE
ASSOCIATED WITH THIS SYSTEM WELL INLAND TODAY. WITH THAT...WILL
MAINTAIN A DRY FORECAST THROUGH THIS AFTERNOON/EVENING.

AS THE MARINE LAYER DEEPENS OVERNIGHT...PATCHY FOG AND DRIZZLE
WILL BE POSSIBLE ALONG THE COAST BY EARLY TUESDAY MORNING.
DAYTIME TEMPERATURES WILL FINALLY COOL INLAND THROUGH MIDWEEK AS
850MB CONDITIONS COOL AHEAD OF AN APPROACHING UPPER LEVEL TROUGH.
THE FORECAST MODELS CONTINUE TO STRUGGLE ON HOW MUCH MOISTURE
WILL BE ADVECTED INTO THE REGION WITH THIS SYSTEM...AND IF THE
ATMOSPHERE WILL BECOME UNSTABLE ENOUGH FOR SHOWERS/THUNDERSTORMS
TO DEVELOP OVER THE INLAND HILLS/MOUNTAINS. FOR NOW...WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORM OVER THE MOUNTAINS OF
SAN BENITO COUNTY FOR TUESDAY AFTERNOON/EVENING AND SHOWERS OVER
MUCH OF THE HIGHER TERRAIN ON WEDNESDAY. AS A BROAD MID/UPPER
LEVEL TROUGH REMAINS OVER MUCH OF THE WEST COAST THROUGH LATE
WEEK WITH WEAK DISTURBANCES MOVING ACROSS THE REGION...CANNOT
RULE OUT A FEW SHOWERS OVER THE INLAND HILLS/MOUNTAINS THROUGH
THURSDAY. THE MEDIUM RANGE MODELS NOW SHOW DRY CONDITIONS
RETURNING TO THE REGION FOR FRIDAY AS THE UPPER LEVEL TROUGH AXIS
SHIFTS INLAND. HAVING SAID ALL THAT...MOST LOCATIONS WILL SEE
LITTLE TO NO RAINFALL THROUGH LATE WEEK.

MUCH OF THE UPCOMING WEEKEND IS NOW FORECAST TO REMAIN DRY WITH
THE UPPER LEVEL STORM TRACK WELL TO THE NORTH. HOWEVER...WILL
CARRY A SLIGHT CHANCE OF PRECIPITATION OVER THE NORTH BAY SUNDAY
INTO MONDAY AS THE 12Z GFS PUSHES A SYSTEM INTO THE PACIFIC
NORTHWEST WITH TRAILING MOISTURE ALONG A FRONTAL BOUNDARY
DROPPING SOUTHWARD. MEANWHILE...THE CMC AND ECMWF MAINTAIN DRY
WEATHER CONDITIONS FOR LATE IN THE FORECAST PERIOD WITH WEAK
RIDING OVER CENTRAL CALIFORNIA. OVERALL...CHANCES FOR MEASURABLE
RAINFALL OVER THE REGION THROUGH THE END OF APRIL ARE LOOKING
MINIMAL AT BEST.

&&

.AVIATION...AS OF 11:00 PM PDT SUNDAY... WIDESPREAD STRATUS
INTRUSION TONIGHT WITH MVFR/IFR CIGS. THERMAL TROUGH BREAKDOWN
BETWEEN 01-02Z ALLOWED FOR A RAPID INTRUSION ONSHORE EARLIER THIS
EVENING. ALL TAF SITES ARE EXPECTED TO BE UNDER STRATUS DECK
THROUGH THE NIGHT AND INTO EARLY TOMORROW MORNING. CEILOMETER DATA
RANGING FROM OVC005 IN THE NORTH BAY TO BKN013 IN THE SOUTH BAY.
CIGS ARE LIKELY TO DESCEND INTO IFR RANGE FOR MANY TAF SITES
OVERNIGHT WITH SOME LOCATIONS SEEING POSSIBLE REDUCTION IN VISBY
BY EARLY MORNING.

VICINITY OF KSFO... STRATUS HAS BEEN FUNNELING THROUGH THE SAN
BRUNO GAP AND GOLDEN GATE REGIONS ON A DUE EAST TRAJECTORY. AS A
RESULT...LOW CIGS HAVE YET TO DIRECTLY IMPACT KSFO. LATEST FOG
PRODUCT SHOWS STRATUS SPREADING NORTHWARD FROM THE SOUTH BAY AND
WILL LIKELY REACH KSFO WITHIN THE NEXT TWO HOURS. KSQL LIKELY
WITHIN THE NEXT HOUR.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CIGS MVFR DETERIORATING TO IFR
OVERNIGHT. SLIGHT RISK OF LIFR VISBYS AROUND SUNRISE.

&&

.MARINE...AS OF 04:37 AM PDT MONDAY...AN UPPER LEVEL LOW PRESSURE
AREA LOCATED 300 MILES SOUTHWEST OF POINT CONCEPTION WILL CONTINUE
TO MOVE SOUTHEAST AND REACH SOUTHERN CALIFORNIA BY EARLY TUESDAY
MORNING. ANOTHER UPPER LEVEL LOW OVER THE EASTERN PACIFIC WILL
REACH THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA BY TUESDAY
NIGHT INTO WEDNESDAY. THIS MAY TEND TO INCREASE NORTHWESTERLY
WINDS OVER THE NORTHERN OUTER COASTAL WATERS BY TUESDAY NIGHT BUT
THERE IS SOME UNCERTAINTY REGARDING WIND STRENGTH AT THIS TIME.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...SF BAY NORTH OF THE BAY BRIDGE

&&

$$

PUBLIC FORECAST: RGASS
AVIATION: DRP
MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 201139
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
439 AM PDT MON APR 20 2015

.SYNOPSIS...COOL CONDITIONS WILL PERSIST NEAR THE COAST TODAY WITH
WARM TEMPERATURES EXPECTED INLAND. TEMPERATURES COOL SLIGHTLY
REGION-WIDE BEGINNING TUESDAY AS A SERIES OF WEAK UPPER LEVEL
SYSTEMS PUSH ACROSS THE REGION. THESE WEAK WEATHER SYSTEMS WILL
PRODUCE A SLIGHT CHANCE OF SHOWERS AT TIMES TUESDAY THROUGH
THURSDAY...BUT MAINLY OVER THE INLAND MOUNTAINS.

&&

.DISCUSSION...AS OF 04:37 AM PDT MONDAY...ONSHORE FLOW AND A
PERSISTENT MARINE LAYER GREATER THAN 2KFT DEEP HAS ALLOWED FOR
LOW CLOUDS TO ONCE AGAIN DEVELOP WELL INLAND INTO MOST VALLEY
LOCATIONS THIS MORNING. THIS HAS HELD OVERNIGHT TEMPERATURES IN
THE LOW/MID 50S REGION-WIDE. MEANWHILE...A WEAK MID/UPPER LEVEL
LOW PRESSURE SYSTEM CONTINUES TO DROP SOUTHWARD OFF OF THE
CENTRAL COAST AND WILL APPROACH THE SOUTHERN CALIFORNIA COAST
DURING THE NEXT 24 HOURS OR SO. AS THIS SYSTEM LINGERS OFF OF THE
COAST...WEATHER CONDITIONS TODAY WILL BE A NEAR REPEAT OF THOSE
ON SUNDAY. THUS...COOL TEMPERATURES NEAR THE COAST WHILE INLAND
AREAS ONCE AGAIN WARM INTO THE 70S AND LOWER 80S. IN
ADDITION...THE FORECAST MODELS KEEP THE BEST MID-LEVEL MOISTURE
ASSOCIATED WITH THIS SYSTEM WELL INLAND TODAY. WITH THAT...WILL
MAINTAIN A DRY FORECAST THROUGH THIS AFTERNOON/EVENING.

AS THE MARINE LAYER DEEPENS OVERNIGHT...PATCHY FOG AND DRIZZLE
WILL BE POSSIBLE ALONG THE COAST BY EARLY TUESDAY MORNING.
DAYTIME TEMPERATURES WILL FINALLY COOL INLAND THROUGH MIDWEEK AS
850MB CONDITIONS COOL AHEAD OF AN APPROACHING UPPER LEVEL TROUGH.
THE FORECAST MODELS CONTINUE TO STRUGGLE ON HOW MUCH MOISTURE
WILL BE ADVECTED INTO THE REGION WITH THIS SYSTEM...AND IF THE
ATMOSPHERE WILL BECOME UNSTABLE ENOUGH FOR SHOWERS/THUNDERSTORMS
TO DEVELOP OVER THE INLAND HILLS/MOUNTAINS. FOR NOW...WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORM OVER THE MOUNTAINS OF
SAN BENITO COUNTY FOR TUESDAY AFTERNOON/EVENING AND SHOWERS OVER
MUCH OF THE HIGHER TERRAIN ON WEDNESDAY. AS A BROAD MID/UPPER
LEVEL TROUGH REMAINS OVER MUCH OF THE WEST COAST THROUGH LATE
WEEK WITH WEAK DISTURBANCES MOVING ACROSS THE REGION...CANNOT
RULE OUT A FEW SHOWERS OVER THE INLAND HILLS/MOUNTAINS THROUGH
THURSDAY. THE MEDIUM RANGE MODELS NOW SHOW DRY CONDITIONS
RETURNING TO THE REGION FOR FRIDAY AS THE UPPER LEVEL TROUGH AXIS
SHIFTS INLAND. HAVING SAID ALL THAT...MOST LOCATIONS WILL SEE
LITTLE TO NO RAINFALL THROUGH LATE WEEK.

MUCH OF THE UPCOMING WEEKEND IS NOW FORECAST TO REMAIN DRY WITH
THE UPPER LEVEL STORM TRACK WELL TO THE NORTH. HOWEVER...WILL
CARRY A SLIGHT CHANCE OF PRECIPITATION OVER THE NORTH BAY SUNDAY
INTO MONDAY AS THE 12Z GFS PUSHES A SYSTEM INTO THE PACIFIC
NORTHWEST WITH TRAILING MOISTURE ALONG A FRONTAL BOUNDARY
DROPPING SOUTHWARD. MEANWHILE...THE CMC AND ECMWF MAINTAIN DRY
WEATHER CONDITIONS FOR LATE IN THE FORECAST PERIOD WITH WEAK
RIDING OVER CENTRAL CALIFORNIA. OVERALL...CHANCES FOR MEASURABLE
RAINFALL OVER THE REGION THROUGH THE END OF APRIL ARE LOOKING
MINIMAL AT BEST.

&&

.AVIATION...AS OF 11:00 PM PDT SUNDAY... WIDESPREAD STRATUS
INTRUSION TONIGHT WITH MVFR/IFR CIGS. THERMAL TROUGH BREAKDOWN
BETWEEN 01-02Z ALLOWED FOR A RAPID INTRUSION ONSHORE EARLIER THIS
EVENING. ALL TAF SITES ARE EXPECTED TO BE UNDER STRATUS DECK
THROUGH THE NIGHT AND INTO EARLY TOMORROW MORNING. CEILOMETER DATA
RANGING FROM OVC005 IN THE NORTH BAY TO BKN013 IN THE SOUTH BAY.
CIGS ARE LIKELY TO DESCEND INTO IFR RANGE FOR MANY TAF SITES
OVERNIGHT WITH SOME LOCATIONS SEEING POSSIBLE REDUCTION IN VISBY
BY EARLY MORNING.

VICINITY OF KSFO... STRATUS HAS BEEN FUNNELING THROUGH THE SAN
BRUNO GAP AND GOLDEN GATE REGIONS ON A DUE EAST TRAJECTORY. AS A
RESULT...LOW CIGS HAVE YET TO DIRECTLY IMPACT KSFO. LATEST FOG
PRODUCT SHOWS STRATUS SPREADING NORTHWARD FROM THE SOUTH BAY AND
WILL LIKELY REACH KSFO WITHIN THE NEXT TWO HOURS. KSQL LIKELY
WITHIN THE NEXT HOUR.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CIGS MVFR DETERIORATING TO IFR
OVERNIGHT. SLIGHT RISK OF LIFR VISBYS AROUND SUNRISE.

&&

.MARINE...AS OF 04:37 AM PDT MONDAY...AN UPPER LEVEL LOW PRESSURE
AREA LOCATED 300 MILES SOUTHWEST OF POINT CONCEPTION WILL CONTINUE
TO MOVE SOUTHEAST AND REACH SOUTHERN CALIFORNIA BY EARLY TUESDAY
MORNING. ANOTHER UPPER LEVEL LOW OVER THE EASTERN PACIFIC WILL
REACH THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA BY TUESDAY
NIGHT INTO WEDNESDAY. THIS MAY TEND TO INCREASE NORTHWESTERLY
WINDS OVER THE NORTHERN OUTER COASTAL WATERS BY TUESDAY NIGHT BUT
THERE IS SOME UNCERTAINTY REGARDING WIND STRENGTH AT THIS TIME.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...SF BAY NORTH OF THE BAY BRIDGE

&&

$$

PUBLIC FORECAST: RGASS
AVIATION: DRP
MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSBAYAREA
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000
FXUS66 KMTR 200608
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1108 PM PDT SUN APR 19 2015

.SYNOPSIS...A RELATIVELY DEEP MARINE LAYER ALONG WITH ONSHORE FLOW
WILL MEAN CONTINUED COOL WEATHER IN COASTAL AREAS ON MONDAY
WHILE INLAND AREAS EXPERIENCE COOLING AS WELL. RELATIVELY COOL
CONDITIONS ARE EXPECTED IN ALL AREAS FOR THE REMAINDER OF THE WEEK
AS A SERIES OF WEAK UPPER LEVEL DISTURBANCES MOVE IN FROM THE
NORTHWEST. THESE WEAK WEATHER SYSTEMS WILL PRODUCE A SLIGHT CHANCE
OF SHOWERS AT TIMES THROUGH MUCH OF THE WEEK...BUT MAINLY OVER THE
MOUNTAINS.

&&

.DISCUSSION...AS OF 9:00 PM PDT SUNDAY...A DEEPER MAINER LAYER AND
STRONGER ONSHORE FLOW RESULTED IN COOLING ACROSS NEARLY OUR ENTIRE
REGION TODAY. ABOUT THE ONLY LOCATIONS THAT REMAINED WARM TODAY
WERE THE INLAND VALLEYS OF SOUTHERN MONTEREY COUNTY AND SAN BENITO
COUNTY WHERE AFTERNOON HIGHS WERE IN THE MID TO UPPER 80S.

WATER VAPOR SATELLITE IMAGERY CURRENTLY SHOWS AN UPPER LEVEL
LOW OFFSHORE...CENTERED ABOUT 350 MILES WEST OF SAN FRANCISCO.
WEAK DISTURBANCES ROTATING AROUND THIS LOW TRIGGERED SCATTERED
THUNDERSTORM ACTIVITY OVER THE SIERRA NEVADA THIS AFTERNOON. THE
UPPER LOW IS FORECAST TO SINK GRADUALLY SOUTH THROUGH LATE
MONDAY AND THEN TURN EASTWARD ON MONDAY NIGHT AND TRACK INLAND
OVER SOUTHERN CALIFORNIA ON TUESDAY. MOST MODEL OUTPUT NOW
INDICATE THAT CONVECTIVE PRECIPITATION ASSOCIATED WITH THIS UPPER
LOW WILL REMAIN OVER THE HIGHER MOUNTAINS...AND OUTSIDE OF OUR
FORECAST AREA. THE EXCEPTION IS THE 18Z GFS WHICH FORECASTS
PRECIPITATION ACROSS SOUTHERN MONTEREY COUNTY ON MONDAY NIGHT.
THIS MODEL IS AN OUTLIER...SO FOR THE TIME BEING WILL KEEP SHOWERS
OUT OF THE FORECAST THROUGH TUESDAY. THE PRIMARY IMPACT THIS UPPER
LEVEL SYSTEM WILL HAVE ON OUR AREA WILL BE TO MAINTAIN A DEEP
MARINE LAYER. AND...AS ONSHORE FLOW INCREASES OVER THE NEXT FEW
DAYS WE MAY SEE PATCHY DRIZZLE FALL OUT OF THIS DEEP MARINE
LAYER...ESPECIALLY IN COASTAL AREAS LATE MONDAY NIGHT AND TUESDAY
MORNING. PERSISTENT LOW CLOUDS WILL MAINTAIN COOLER-THAN-NORMAL
CONDITIONS IN COASTAL AREAS THROUGH TUESDAY...WITH A CONTINUATION
OF A COOLING TREND INLAND.

A COUPLE OF COOL WEATHER SYSTEMS ARE FORECAST TO SWEEP IN FROM THE
NORTH OR NORTHWEST LATER THIS WEEK. THE FIRST ONE WILL DROP SOUTH
ALONG THE COAST LATE TUESDAY AND TUESDAY NIGHT. THIS SYSTEM WILL
BRING ENOUGH COOL AIR TO MIX OUT THE MARINE LAYER BY WEDNESDAY.
THUS...WE WILL PROBABLY SEE MORE SUN IN COASTAL AREAS BY MIDWEEK
AND SLIGHT WARMING AT THE COAST ON WEDNESDAY. BUT COOLING WILL
CONTINUE FOR THE INLAND VALLEYS THROUGH WEDNESDAY. BY MIDWEEK HIGH
TEMPERATURES FOR THE SOUTHERN INTERIOR VALLEYS WILL BE A MUCH AS
20 DEGREES COOLER THAN TODAY. A SECOND SYSTEM WILL MOVE IN FROM
THE NORTHWEST LATER IN THE WEEK...BUT THE MODELS DISAGREE ON THE
EXACT TRAJECTORY. EARLIER MODEL RUNS HAD INDICATED THESE SYSTEMS
WOULD GIVE US A DECENT CHANCE OF SHOWER ACTIVITY AT TIMES FROM
LATE TUESDAY THROUGH THE END OF THE WEEK...ESPECIALLY ACROSS
HIGHER TERRAIN. BUT RECENT MODEL TRENDS HAVE BEEN FOR LESS PRECIP
AND SO SLIGHT CHANCE POPS THIS WEEK ARE PROBABLY SUFFICIENT.

&&

.AVIATION...AS OF 11:00 PM PDT SUNDAY... WIDESPREAD STRATUS
INTRUSION TONIGHT WITH MVFR/IFR CIGS. THERMAL TROUGH BREAKDOWN
BETWEEN 01-02Z ALLOWED FOR A RAPID INTRUSION ONSHORE EARLIER THIS
EVENING. ALL TAF SITES ARE EXPECTED TO BE UNDER STRATUS DECK
THROUGH THE NIGHT AND INTO EARLY TOMORROW MORNING. CEILOMETER DATA
RANGING FROM OVC005 IN THE NORTH BAY TO BKN013 IN THE SOUTH BAY.
CIGS ARE LIKELY TO DESCEND INTO IFR RANGE FOR MANY TAF SITES
OVERNIGHT WITH SOME LOCATIONS SEEING POSSIBLE REDUCTION IN VISBY
BY EARLY MORNING.

VICINITY OF KSFO... STRATUS HAS BEEN FUNNELING THROUGH THE SAN
BRUNO GAP AND GOLDEN GATE REGIONS ON A DUE EAST TRAJECTORY. AS A
RESULT...LOW CIGS HAVE YET TO DIRECTLY IMPACT KSFO. LATEST FOG
PRODUCT SHOWS STRATUS SPREADING NORTHWARD FROM THE SOUTH BAY AND
WILL LIKELY REACH KSFO WITHIN THE NEXT TWO HOURS. KSQL LIKELY
WITHIN THE NEXT HOUR.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CIGS MVFR DETERIORATING TO IFR
OVERNIGHT. SLIGHT RISK OF LIFR VISBYS AROUND SUNRISE.

&&

.MARINE...AS OF 11:07 PM PDT SUNDAY...MARINE LAYER WILL BE PRESENT
OVER THE COASTAL WATERS INTO TOMORROW LEADING TO AREAS OF PATCHY
FOG ALONG THE COAST. WINDS WILL BE PREDOMINATELY LIGHT AND OUT OF
THE NORTHWEST WITH GENTLE SEAS THROUGH THE NEXT 24 HOURS. THE
PATTERN SHIFTS BY TUESDAY WITH INCREASING WINDS AND BUILDING SEAS.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...NONE.

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 200608
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1108 PM PDT SUN APR 19 2015

.SYNOPSIS...A RELATIVELY DEEP MARINE LAYER ALONG WITH ONSHORE FLOW
WILL MEAN CONTINUED COOL WEATHER IN COASTAL AREAS ON MONDAY
WHILE INLAND AREAS EXPERIENCE COOLING AS WELL. RELATIVELY COOL
CONDITIONS ARE EXPECTED IN ALL AREAS FOR THE REMAINDER OF THE WEEK
AS A SERIES OF WEAK UPPER LEVEL DISTURBANCES MOVE IN FROM THE
NORTHWEST. THESE WEAK WEATHER SYSTEMS WILL PRODUCE A SLIGHT CHANCE
OF SHOWERS AT TIMES THROUGH MUCH OF THE WEEK...BUT MAINLY OVER THE
MOUNTAINS.

&&

.DISCUSSION...AS OF 9:00 PM PDT SUNDAY...A DEEPER MAINER LAYER AND
STRONGER ONSHORE FLOW RESULTED IN COOLING ACROSS NEARLY OUR ENTIRE
REGION TODAY. ABOUT THE ONLY LOCATIONS THAT REMAINED WARM TODAY
WERE THE INLAND VALLEYS OF SOUTHERN MONTEREY COUNTY AND SAN BENITO
COUNTY WHERE AFTERNOON HIGHS WERE IN THE MID TO UPPER 80S.

WATER VAPOR SATELLITE IMAGERY CURRENTLY SHOWS AN UPPER LEVEL
LOW OFFSHORE...CENTERED ABOUT 350 MILES WEST OF SAN FRANCISCO.
WEAK DISTURBANCES ROTATING AROUND THIS LOW TRIGGERED SCATTERED
THUNDERSTORM ACTIVITY OVER THE SIERRA NEVADA THIS AFTERNOON. THE
UPPER LOW IS FORECAST TO SINK GRADUALLY SOUTH THROUGH LATE
MONDAY AND THEN TURN EASTWARD ON MONDAY NIGHT AND TRACK INLAND
OVER SOUTHERN CALIFORNIA ON TUESDAY. MOST MODEL OUTPUT NOW
INDICATE THAT CONVECTIVE PRECIPITATION ASSOCIATED WITH THIS UPPER
LOW WILL REMAIN OVER THE HIGHER MOUNTAINS...AND OUTSIDE OF OUR
FORECAST AREA. THE EXCEPTION IS THE 18Z GFS WHICH FORECASTS
PRECIPITATION ACROSS SOUTHERN MONTEREY COUNTY ON MONDAY NIGHT.
THIS MODEL IS AN OUTLIER...SO FOR THE TIME BEING WILL KEEP SHOWERS
OUT OF THE FORECAST THROUGH TUESDAY. THE PRIMARY IMPACT THIS UPPER
LEVEL SYSTEM WILL HAVE ON OUR AREA WILL BE TO MAINTAIN A DEEP
MARINE LAYER. AND...AS ONSHORE FLOW INCREASES OVER THE NEXT FEW
DAYS WE MAY SEE PATCHY DRIZZLE FALL OUT OF THIS DEEP MARINE
LAYER...ESPECIALLY IN COASTAL AREAS LATE MONDAY NIGHT AND TUESDAY
MORNING. PERSISTENT LOW CLOUDS WILL MAINTAIN COOLER-THAN-NORMAL
CONDITIONS IN COASTAL AREAS THROUGH TUESDAY...WITH A CONTINUATION
OF A COOLING TREND INLAND.

A COUPLE OF COOL WEATHER SYSTEMS ARE FORECAST TO SWEEP IN FROM THE
NORTH OR NORTHWEST LATER THIS WEEK. THE FIRST ONE WILL DROP SOUTH
ALONG THE COAST LATE TUESDAY AND TUESDAY NIGHT. THIS SYSTEM WILL
BRING ENOUGH COOL AIR TO MIX OUT THE MARINE LAYER BY WEDNESDAY.
THUS...WE WILL PROBABLY SEE MORE SUN IN COASTAL AREAS BY MIDWEEK
AND SLIGHT WARMING AT THE COAST ON WEDNESDAY. BUT COOLING WILL
CONTINUE FOR THE INLAND VALLEYS THROUGH WEDNESDAY. BY MIDWEEK HIGH
TEMPERATURES FOR THE SOUTHERN INTERIOR VALLEYS WILL BE A MUCH AS
20 DEGREES COOLER THAN TODAY. A SECOND SYSTEM WILL MOVE IN FROM
THE NORTHWEST LATER IN THE WEEK...BUT THE MODELS DISAGREE ON THE
EXACT TRAJECTORY. EARLIER MODEL RUNS HAD INDICATED THESE SYSTEMS
WOULD GIVE US A DECENT CHANCE OF SHOWER ACTIVITY AT TIMES FROM
LATE TUESDAY THROUGH THE END OF THE WEEK...ESPECIALLY ACROSS
HIGHER TERRAIN. BUT RECENT MODEL TRENDS HAVE BEEN FOR LESS PRECIP
AND SO SLIGHT CHANCE POPS THIS WEEK ARE PROBABLY SUFFICIENT.

&&

.AVIATION...AS OF 11:00 PM PDT SUNDAY... WIDESPREAD STRATUS
INTRUSION TONIGHT WITH MVFR/IFR CIGS. THERMAL TROUGH BREAKDOWN
BETWEEN 01-02Z ALLOWED FOR A RAPID INTRUSION ONSHORE EARLIER THIS
EVENING. ALL TAF SITES ARE EXPECTED TO BE UNDER STRATUS DECK
THROUGH THE NIGHT AND INTO EARLY TOMORROW MORNING. CEILOMETER DATA
RANGING FROM OVC005 IN THE NORTH BAY TO BKN013 IN THE SOUTH BAY.
CIGS ARE LIKELY TO DESCEND INTO IFR RANGE FOR MANY TAF SITES
OVERNIGHT WITH SOME LOCATIONS SEEING POSSIBLE REDUCTION IN VISBY
BY EARLY MORNING.

VICINITY OF KSFO... STRATUS HAS BEEN FUNNELING THROUGH THE SAN
BRUNO GAP AND GOLDEN GATE REGIONS ON A DUE EAST TRAJECTORY. AS A
RESULT...LOW CIGS HAVE YET TO DIRECTLY IMPACT KSFO. LATEST FOG
PRODUCT SHOWS STRATUS SPREADING NORTHWARD FROM THE SOUTH BAY AND
WILL LIKELY REACH KSFO WITHIN THE NEXT TWO HOURS. KSQL LIKELY
WITHIN THE NEXT HOUR.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CIGS MVFR DETERIORATING TO IFR
OVERNIGHT. SLIGHT RISK OF LIFR VISBYS AROUND SUNRISE.

&&

.MARINE...AS OF 11:07 PM PDT SUNDAY...MARINE LAYER WILL BE PRESENT
OVER THE COASTAL WATERS INTO TOMORROW LEADING TO AREAS OF PATCHY
FOG ALONG THE COAST. WINDS WILL BE PREDOMINATELY LIGHT AND OUT OF
THE NORTHWEST WITH GENTLE SEAS THROUGH THE NEXT 24 HOURS. THE
PATTERN SHIFTS BY TUESDAY WITH INCREASING WINDS AND BUILDING SEAS.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...NONE.

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 200608
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1108 PM PDT SUN APR 19 2015

.SYNOPSIS...A RELATIVELY DEEP MARINE LAYER ALONG WITH ONSHORE FLOW
WILL MEAN CONTINUED COOL WEATHER IN COASTAL AREAS ON MONDAY
WHILE INLAND AREAS EXPERIENCE COOLING AS WELL. RELATIVELY COOL
CONDITIONS ARE EXPECTED IN ALL AREAS FOR THE REMAINDER OF THE WEEK
AS A SERIES OF WEAK UPPER LEVEL DISTURBANCES MOVE IN FROM THE
NORTHWEST. THESE WEAK WEATHER SYSTEMS WILL PRODUCE A SLIGHT CHANCE
OF SHOWERS AT TIMES THROUGH MUCH OF THE WEEK...BUT MAINLY OVER THE
MOUNTAINS.

&&

.DISCUSSION...AS OF 9:00 PM PDT SUNDAY...A DEEPER MAINER LAYER AND
STRONGER ONSHORE FLOW RESULTED IN COOLING ACROSS NEARLY OUR ENTIRE
REGION TODAY. ABOUT THE ONLY LOCATIONS THAT REMAINED WARM TODAY
WERE THE INLAND VALLEYS OF SOUTHERN MONTEREY COUNTY AND SAN BENITO
COUNTY WHERE AFTERNOON HIGHS WERE IN THE MID TO UPPER 80S.

WATER VAPOR SATELLITE IMAGERY CURRENTLY SHOWS AN UPPER LEVEL
LOW OFFSHORE...CENTERED ABOUT 350 MILES WEST OF SAN FRANCISCO.
WEAK DISTURBANCES ROTATING AROUND THIS LOW TRIGGERED SCATTERED
THUNDERSTORM ACTIVITY OVER THE SIERRA NEVADA THIS AFTERNOON. THE
UPPER LOW IS FORECAST TO SINK GRADUALLY SOUTH THROUGH LATE
MONDAY AND THEN TURN EASTWARD ON MONDAY NIGHT AND TRACK INLAND
OVER SOUTHERN CALIFORNIA ON TUESDAY. MOST MODEL OUTPUT NOW
INDICATE THAT CONVECTIVE PRECIPITATION ASSOCIATED WITH THIS UPPER
LOW WILL REMAIN OVER THE HIGHER MOUNTAINS...AND OUTSIDE OF OUR
FORECAST AREA. THE EXCEPTION IS THE 18Z GFS WHICH FORECASTS
PRECIPITATION ACROSS SOUTHERN MONTEREY COUNTY ON MONDAY NIGHT.
THIS MODEL IS AN OUTLIER...SO FOR THE TIME BEING WILL KEEP SHOWERS
OUT OF THE FORECAST THROUGH TUESDAY. THE PRIMARY IMPACT THIS UPPER
LEVEL SYSTEM WILL HAVE ON OUR AREA WILL BE TO MAINTAIN A DEEP
MARINE LAYER. AND...AS ONSHORE FLOW INCREASES OVER THE NEXT FEW
DAYS WE MAY SEE PATCHY DRIZZLE FALL OUT OF THIS DEEP MARINE
LAYER...ESPECIALLY IN COASTAL AREAS LATE MONDAY NIGHT AND TUESDAY
MORNING. PERSISTENT LOW CLOUDS WILL MAINTAIN COOLER-THAN-NORMAL
CONDITIONS IN COASTAL AREAS THROUGH TUESDAY...WITH A CONTINUATION
OF A COOLING TREND INLAND.

A COUPLE OF COOL WEATHER SYSTEMS ARE FORECAST TO SWEEP IN FROM THE
NORTH OR NORTHWEST LATER THIS WEEK. THE FIRST ONE WILL DROP SOUTH
ALONG THE COAST LATE TUESDAY AND TUESDAY NIGHT. THIS SYSTEM WILL
BRING ENOUGH COOL AIR TO MIX OUT THE MARINE LAYER BY WEDNESDAY.
THUS...WE WILL PROBABLY SEE MORE SUN IN COASTAL AREAS BY MIDWEEK
AND SLIGHT WARMING AT THE COAST ON WEDNESDAY. BUT COOLING WILL
CONTINUE FOR THE INLAND VALLEYS THROUGH WEDNESDAY. BY MIDWEEK HIGH
TEMPERATURES FOR THE SOUTHERN INTERIOR VALLEYS WILL BE A MUCH AS
20 DEGREES COOLER THAN TODAY. A SECOND SYSTEM WILL MOVE IN FROM
THE NORTHWEST LATER IN THE WEEK...BUT THE MODELS DISAGREE ON THE
EXACT TRAJECTORY. EARLIER MODEL RUNS HAD INDICATED THESE SYSTEMS
WOULD GIVE US A DECENT CHANCE OF SHOWER ACTIVITY AT TIMES FROM
LATE TUESDAY THROUGH THE END OF THE WEEK...ESPECIALLY ACROSS
HIGHER TERRAIN. BUT RECENT MODEL TRENDS HAVE BEEN FOR LESS PRECIP
AND SO SLIGHT CHANCE POPS THIS WEEK ARE PROBABLY SUFFICIENT.

&&

.AVIATION...AS OF 11:00 PM PDT SUNDAY... WIDESPREAD STRATUS
INTRUSION TONIGHT WITH MVFR/IFR CIGS. THERMAL TROUGH BREAKDOWN
BETWEEN 01-02Z ALLOWED FOR A RAPID INTRUSION ONSHORE EARLIER THIS
EVENING. ALL TAF SITES ARE EXPECTED TO BE UNDER STRATUS DECK
THROUGH THE NIGHT AND INTO EARLY TOMORROW MORNING. CEILOMETER DATA
RANGING FROM OVC005 IN THE NORTH BAY TO BKN013 IN THE SOUTH BAY.
CIGS ARE LIKELY TO DESCEND INTO IFR RANGE FOR MANY TAF SITES
OVERNIGHT WITH SOME LOCATIONS SEEING POSSIBLE REDUCTION IN VISBY
BY EARLY MORNING.

VICINITY OF KSFO... STRATUS HAS BEEN FUNNELING THROUGH THE SAN
BRUNO GAP AND GOLDEN GATE REGIONS ON A DUE EAST TRAJECTORY. AS A
RESULT...LOW CIGS HAVE YET TO DIRECTLY IMPACT KSFO. LATEST FOG
PRODUCT SHOWS STRATUS SPREADING NORTHWARD FROM THE SOUTH BAY AND
WILL LIKELY REACH KSFO WITHIN THE NEXT TWO HOURS. KSQL LIKELY
WITHIN THE NEXT HOUR.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CIGS MVFR DETERIORATING TO IFR
OVERNIGHT. SLIGHT RISK OF LIFR VISBYS AROUND SUNRISE.

&&

.MARINE...AS OF 11:07 PM PDT SUNDAY...MARINE LAYER WILL BE PRESENT
OVER THE COASTAL WATERS INTO TOMORROW LEADING TO AREAS OF PATCHY
FOG ALONG THE COAST. WINDS WILL BE PREDOMINATELY LIGHT AND OUT OF
THE NORTHWEST WITH GENTLE SEAS THROUGH THE NEXT 24 HOURS. THE
PATTERN SHIFTS BY TUESDAY WITH INCREASING WINDS AND BUILDING SEAS.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...NONE.

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 200608
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1108 PM PDT SUN APR 19 2015

.SYNOPSIS...A RELATIVELY DEEP MARINE LAYER ALONG WITH ONSHORE FLOW
WILL MEAN CONTINUED COOL WEATHER IN COASTAL AREAS ON MONDAY
WHILE INLAND AREAS EXPERIENCE COOLING AS WELL. RELATIVELY COOL
CONDITIONS ARE EXPECTED IN ALL AREAS FOR THE REMAINDER OF THE WEEK
AS A SERIES OF WEAK UPPER LEVEL DISTURBANCES MOVE IN FROM THE
NORTHWEST. THESE WEAK WEATHER SYSTEMS WILL PRODUCE A SLIGHT CHANCE
OF SHOWERS AT TIMES THROUGH MUCH OF THE WEEK...BUT MAINLY OVER THE
MOUNTAINS.

&&

.DISCUSSION...AS OF 9:00 PM PDT SUNDAY...A DEEPER MAINER LAYER AND
STRONGER ONSHORE FLOW RESULTED IN COOLING ACROSS NEARLY OUR ENTIRE
REGION TODAY. ABOUT THE ONLY LOCATIONS THAT REMAINED WARM TODAY
WERE THE INLAND VALLEYS OF SOUTHERN MONTEREY COUNTY AND SAN BENITO
COUNTY WHERE AFTERNOON HIGHS WERE IN THE MID TO UPPER 80S.

WATER VAPOR SATELLITE IMAGERY CURRENTLY SHOWS AN UPPER LEVEL
LOW OFFSHORE...CENTERED ABOUT 350 MILES WEST OF SAN FRANCISCO.
WEAK DISTURBANCES ROTATING AROUND THIS LOW TRIGGERED SCATTERED
THUNDERSTORM ACTIVITY OVER THE SIERRA NEVADA THIS AFTERNOON. THE
UPPER LOW IS FORECAST TO SINK GRADUALLY SOUTH THROUGH LATE
MONDAY AND THEN TURN EASTWARD ON MONDAY NIGHT AND TRACK INLAND
OVER SOUTHERN CALIFORNIA ON TUESDAY. MOST MODEL OUTPUT NOW
INDICATE THAT CONVECTIVE PRECIPITATION ASSOCIATED WITH THIS UPPER
LOW WILL REMAIN OVER THE HIGHER MOUNTAINS...AND OUTSIDE OF OUR
FORECAST AREA. THE EXCEPTION IS THE 18Z GFS WHICH FORECASTS
PRECIPITATION ACROSS SOUTHERN MONTEREY COUNTY ON MONDAY NIGHT.
THIS MODEL IS AN OUTLIER...SO FOR THE TIME BEING WILL KEEP SHOWERS
OUT OF THE FORECAST THROUGH TUESDAY. THE PRIMARY IMPACT THIS UPPER
LEVEL SYSTEM WILL HAVE ON OUR AREA WILL BE TO MAINTAIN A DEEP
MARINE LAYER. AND...AS ONSHORE FLOW INCREASES OVER THE NEXT FEW
DAYS WE MAY SEE PATCHY DRIZZLE FALL OUT OF THIS DEEP MARINE
LAYER...ESPECIALLY IN COASTAL AREAS LATE MONDAY NIGHT AND TUESDAY
MORNING. PERSISTENT LOW CLOUDS WILL MAINTAIN COOLER-THAN-NORMAL
CONDITIONS IN COASTAL AREAS THROUGH TUESDAY...WITH A CONTINUATION
OF A COOLING TREND INLAND.

A COUPLE OF COOL WEATHER SYSTEMS ARE FORECAST TO SWEEP IN FROM THE
NORTH OR NORTHWEST LATER THIS WEEK. THE FIRST ONE WILL DROP SOUTH
ALONG THE COAST LATE TUESDAY AND TUESDAY NIGHT. THIS SYSTEM WILL
BRING ENOUGH COOL AIR TO MIX OUT THE MARINE LAYER BY WEDNESDAY.
THUS...WE WILL PROBABLY SEE MORE SUN IN COASTAL AREAS BY MIDWEEK
AND SLIGHT WARMING AT THE COAST ON WEDNESDAY. BUT COOLING WILL
CONTINUE FOR THE INLAND VALLEYS THROUGH WEDNESDAY. BY MIDWEEK HIGH
TEMPERATURES FOR THE SOUTHERN INTERIOR VALLEYS WILL BE A MUCH AS
20 DEGREES COOLER THAN TODAY. A SECOND SYSTEM WILL MOVE IN FROM
THE NORTHWEST LATER IN THE WEEK...BUT THE MODELS DISAGREE ON THE
EXACT TRAJECTORY. EARLIER MODEL RUNS HAD INDICATED THESE SYSTEMS
WOULD GIVE US A DECENT CHANCE OF SHOWER ACTIVITY AT TIMES FROM
LATE TUESDAY THROUGH THE END OF THE WEEK...ESPECIALLY ACROSS
HIGHER TERRAIN. BUT RECENT MODEL TRENDS HAVE BEEN FOR LESS PRECIP
AND SO SLIGHT CHANCE POPS THIS WEEK ARE PROBABLY SUFFICIENT.

&&

.AVIATION...AS OF 11:00 PM PDT SUNDAY... WIDESPREAD STRATUS
INTRUSION TONIGHT WITH MVFR/IFR CIGS. THERMAL TROUGH BREAKDOWN
BETWEEN 01-02Z ALLOWED FOR A RAPID INTRUSION ONSHORE EARLIER THIS
EVENING. ALL TAF SITES ARE EXPECTED TO BE UNDER STRATUS DECK
THROUGH THE NIGHT AND INTO EARLY TOMORROW MORNING. CEILOMETER DATA
RANGING FROM OVC005 IN THE NORTH BAY TO BKN013 IN THE SOUTH BAY.
CIGS ARE LIKELY TO DESCEND INTO IFR RANGE FOR MANY TAF SITES
OVERNIGHT WITH SOME LOCATIONS SEEING POSSIBLE REDUCTION IN VISBY
BY EARLY MORNING.

VICINITY OF KSFO... STRATUS HAS BEEN FUNNELING THROUGH THE SAN
BRUNO GAP AND GOLDEN GATE REGIONS ON A DUE EAST TRAJECTORY. AS A
RESULT...LOW CIGS HAVE YET TO DIRECTLY IMPACT KSFO. LATEST FOG
PRODUCT SHOWS STRATUS SPREADING NORTHWARD FROM THE SOUTH BAY AND
WILL LIKELY REACH KSFO WITHIN THE NEXT TWO HOURS. KSQL LIKELY
WITHIN THE NEXT HOUR.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CIGS MVFR DETERIORATING TO IFR
OVERNIGHT. SLIGHT RISK OF LIFR VISBYS AROUND SUNRISE.

&&

.MARINE...AS OF 11:07 PM PDT SUNDAY...MARINE LAYER WILL BE PRESENT
OVER THE COASTAL WATERS INTO TOMORROW LEADING TO AREAS OF PATCHY
FOG ALONG THE COAST. WINDS WILL BE PREDOMINATELY LIGHT AND OUT OF
THE NORTHWEST WITH GENTLE SEAS THROUGH THE NEXT 24 HOURS. THE
PATTERN SHIFTS BY TUESDAY WITH INCREASING WINDS AND BUILDING SEAS.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...NONE.

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 200400
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
900 PM PDT SUN APR 19 2015

.SYNOPSIS...A RELATIVELY DEEP MARINE LAYER ALONG WITH ONSHORE FLOW
WILL MEAN CONTINUED COOL WEATHER IN COASTAL AREAS ON MONDAY
WHILE INLAND AREAS EXPERIENCE COOLING AS WELL. RELATIVELY COOL
CONDITIONS ARE EXPECTED IN ALL AREAS FOR THE REMAINDER OF THE WEEK
AS A SERIES OF WEAK UPPER LEVEL DISTURBANCES MOVE IN FROM THE
NORTHWEST. THESE WEAK WEATHER SYSTEMS WILL PRODUCE A SLIGHT CHANCE
OF SHOWERS AT TIMES THROUGH MUCH OF THE WEEK...BUT MAINLY OVER THE
MOUNTAINS.

&&

.DISCUSSION...AS OF 9:00 PM PDT SUNDAY...A DEEPER MAINER LAYER AND
STRONGER ONSHORE FLOW RESULTED IN COOLING ACROSS NEARLY OUR ENTIRE
REGION TODAY. ABOUT THE ONLY LOCATIONS THAT REMAINED WARM TODAY
WERE THE INLAND VALLEYS OF SOUTHERN MONTEREY COUNTY AND SAN BENITO
COUNTY WHERE AFTERNOON HIGHS WERE IN THE MID TO UPPER 80S.

WATER VAPOR SATELLITE IMAGERY CURRENTLY SHOWS AN UPPER LEVEL
LOW OFFSHORE...CENTERED ABOUT 350 MILES WEST OF SAN FRANCISCO.
WEAK DISTURBANCES ROTATING AROUND THIS LOW TRIGGERED SCATTERED
THUNDERSTORM ACTIVITY OVER THE SIERRA NEVADA THIS AFTERNOON. THE
UPPER LOW IS FORECAST TO SINK GRADUALLY SOUTH THROUGH LATE
MONDAY AND THEN TURN EASTWARD ON MONDAY NIGHT AND TRACK INLAND
OVER SOUTHERN CALIFORNIA ON TUESDAY. MOST MODEL OUTPUT NOW
INDICATE THAT CONVECTIVE PRECIPITATION ASSOCIATED WITH THIS UPPER
LOW WILL REMAIN OVER THE HIGHER MOUNTAINS...AND OUTSIDE OF OUR
FORECAST AREA. THE EXCEPTION IS THE 18Z GFS WHICH FORECASTS
PRECIPITATION ACROSS SOUTHERN MONTEREY COUNTY ON MONDAY NIGHT.
THIS MODEL IS AN OUTLIER...SO FOR THE TIME BEING WILL KEEP SHOWERS
OUT OF THE FORECAST THROUGH TUESDAY. THE PRIMARY IMPACT THIS UPPER
LEVEL SYSTEM WILL HAVE ON OUR AREA WILL BE TO MAINTAIN A DEEP
MARINE LAYER. AND...AS ONSHORE FLOW INCREASES OVER THE NEXT FEW
DAYS WE MAY SEE PATCHY DRIZZLE FALL OUT OF THIS DEEP MARINE
LAYER...ESPECIALLY IN COASTAL AREAS LATE MONDAY NIGHT AND TUESDAY
MORNING. PERSISTENT LOW CLOUDS WILL MAINTAIN COOLER-THAN-NORMAL
CONDITIONS IN COASTAL AREAS THROUGH TUESDAY...WITH A CONTINUATION
OF A COOLING TREND INLAND.

A COUPLE OF COOL WEATHER SYSTEMS ARE FORECAST TO SWEEP IN FROM THE
NORTH OR NORTHWEST LATER THIS WEEK. THE FIRST ONE WILL DROP SOUTH
ALONG THE COAST LATE TUESDAY AND TUESDAY NIGHT. THIS SYSTEM WILL
BRING ENOUGH COOL AIR TO MIX OUT THE MARINE LAYER BY WEDNESDAY.
THUS...WE WILL PROBABLY SEE MORE SUN IN COASTAL AREAS BY MIDWEEK
AND SLIGHT WARMING AT THE COAST ON WEDNESDAY. BUT COOLING WILL
CONTINUE FOR THE INLAND VALLEYS THROUGH WEDNESDAY. BY MIDWEEK HIGH
TEMPERATURES FOR THE SOUTHERN INTERIOR VALLEYS WILL BE A MUCH AS
20 DEGREES COOLER THAN TODAY. A SECOND SYSTEM WILL MOVE IN FROM
THE NORTHWEST LATER IN THE WEEK...BUT THE MODELS DISAGREE ON THE
EXACT TRAJECTORY. EARLIER MODEL RUNS HAD INDICATED THESE SYSTEMS
WOULD GIVE US A DECENT CHANCE OF SHOWER ACTIVITY AT TIMES FROM
LATE TUESDAY THROUGH THE END OF THE WEEK...ESPECIALLY ACROSS
HIGHER TERRAIN. BUT RECENT MODEL TRENDS HAVE BEEN FOR LESS PRECIP
AND SO SLIGHT CHANCE POPS THIS WEEK ARE PROBABLY SUFFICIENT.

&&

.AVIATION...AS OF 5:15 PM PDT SUNDAY...SATELLITE IMAGERY SHOWS
A LEISURELY PROGRESSION OF MARINE STRATUS ONSHORE ALREADY THIS
AFTERNOON. KMRY KSNS AND KWVI ARE/WILL SHORTLY BE UNDER THE
STRATUS LAYER THROUGH LATE MORNING MONDAY. ELSEWHERE... THE MARINE
STRATUS IS CREEPING ONSHORE ALONG THE ENTIRE COASTLINE.
PROGRESSION IS LIKELY TO STALL FOR A TIME AS THE MARINE AIR MASS
INTERACTS WITH A LESS ACCOMMODATING AIR MASS ONSHORE. THIS SHOULD
KEEP THE BAY AREA TERMINALS IN VFR CONDITIONS FOR A FEW MORE HOURS...
WITH SLIGHTLY INCREASING ODDS OF STRATUS BREAKING THROUGH WITH EACH
PROGRESSIVE HOUR. OVERALL... HIGH CONFIDENCE ON STRATUS THIS
EVENING... LOW CONFIDENCE ON PRECISE TIMING.

VICINITY OF KSFO... SAN BRUNO GAP CAM LOOKS OMINOUS WITH MARINE
STRATUS CLEARLY PRESENT. EXPECT TO SEE VFR THROUGH AT LEAST 03Z
WITH MVFR/IFR LIKELY BY NO LATER THAN 07Z. WILL KEEP WATCH FOR
ARRIVALS BETWEEN 04-07Z AND UPGRADE THE TAF AS NECESSARY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CIGS MVFR DETERIORATING TO IFR
OVERNIGHT. SLIGHT RISK OF LIFR VISBYS AROUND SUNRISE.

&&

.MARINE...AS OF 8:46 PM PDT SUNDAY...MARINE LAYER WILL BE PRESENT
OVER THE COASTAL WATERS INTO TOMORROW LEADING TO AREAS OF PATCHY
FOG ALONG THE COAST. WINDS WILL BE PREDOMINATELY LIGHT AND OUT OF
THE NORTHWEST WITH GENTLE SEAS THROUGH THE NEXT 24 HOURS. THE
PATTERN SHIFTS BY TUESDAY WITH INCREASING WINDS AND BUILDING SEAS.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...NONE.

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 200400
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
900 PM PDT SUN APR 19 2015

.SYNOPSIS...A RELATIVELY DEEP MARINE LAYER ALONG WITH ONSHORE FLOW
WILL MEAN CONTINUED COOL WEATHER IN COASTAL AREAS ON MONDAY
WHILE INLAND AREAS EXPERIENCE COOLING AS WELL. RELATIVELY COOL
CONDITIONS ARE EXPECTED IN ALL AREAS FOR THE REMAINDER OF THE WEEK
AS A SERIES OF WEAK UPPER LEVEL DISTURBANCES MOVE IN FROM THE
NORTHWEST. THESE WEAK WEATHER SYSTEMS WILL PRODUCE A SLIGHT CHANCE
OF SHOWERS AT TIMES THROUGH MUCH OF THE WEEK...BUT MAINLY OVER THE
MOUNTAINS.

&&

.DISCUSSION...AS OF 9:00 PM PDT SUNDAY...A DEEPER MAINER LAYER AND
STRONGER ONSHORE FLOW RESULTED IN COOLING ACROSS NEARLY OUR ENTIRE
REGION TODAY. ABOUT THE ONLY LOCATIONS THAT REMAINED WARM TODAY
WERE THE INLAND VALLEYS OF SOUTHERN MONTEREY COUNTY AND SAN BENITO
COUNTY WHERE AFTERNOON HIGHS WERE IN THE MID TO UPPER 80S.

WATER VAPOR SATELLITE IMAGERY CURRENTLY SHOWS AN UPPER LEVEL
LOW OFFSHORE...CENTERED ABOUT 350 MILES WEST OF SAN FRANCISCO.
WEAK DISTURBANCES ROTATING AROUND THIS LOW TRIGGERED SCATTERED
THUNDERSTORM ACTIVITY OVER THE SIERRA NEVADA THIS AFTERNOON. THE
UPPER LOW IS FORECAST TO SINK GRADUALLY SOUTH THROUGH LATE
MONDAY AND THEN TURN EASTWARD ON MONDAY NIGHT AND TRACK INLAND
OVER SOUTHERN CALIFORNIA ON TUESDAY. MOST MODEL OUTPUT NOW
INDICATE THAT CONVECTIVE PRECIPITATION ASSOCIATED WITH THIS UPPER
LOW WILL REMAIN OVER THE HIGHER MOUNTAINS...AND OUTSIDE OF OUR
FORECAST AREA. THE EXCEPTION IS THE 18Z GFS WHICH FORECASTS
PRECIPITATION ACROSS SOUTHERN MONTEREY COUNTY ON MONDAY NIGHT.
THIS MODEL IS AN OUTLIER...SO FOR THE TIME BEING WILL KEEP SHOWERS
OUT OF THE FORECAST THROUGH TUESDAY. THE PRIMARY IMPACT THIS UPPER
LEVEL SYSTEM WILL HAVE ON OUR AREA WILL BE TO MAINTAIN A DEEP
MARINE LAYER. AND...AS ONSHORE FLOW INCREASES OVER THE NEXT FEW
DAYS WE MAY SEE PATCHY DRIZZLE FALL OUT OF THIS DEEP MARINE
LAYER...ESPECIALLY IN COASTAL AREAS LATE MONDAY NIGHT AND TUESDAY
MORNING. PERSISTENT LOW CLOUDS WILL MAINTAIN COOLER-THAN-NORMAL
CONDITIONS IN COASTAL AREAS THROUGH TUESDAY...WITH A CONTINUATION
OF A COOLING TREND INLAND.

A COUPLE OF COOL WEATHER SYSTEMS ARE FORECAST TO SWEEP IN FROM THE
NORTH OR NORTHWEST LATER THIS WEEK. THE FIRST ONE WILL DROP SOUTH
ALONG THE COAST LATE TUESDAY AND TUESDAY NIGHT. THIS SYSTEM WILL
BRING ENOUGH COOL AIR TO MIX OUT THE MARINE LAYER BY WEDNESDAY.
THUS...WE WILL PROBABLY SEE MORE SUN IN COASTAL AREAS BY MIDWEEK
AND SLIGHT WARMING AT THE COAST ON WEDNESDAY. BUT COOLING WILL
CONTINUE FOR THE INLAND VALLEYS THROUGH WEDNESDAY. BY MIDWEEK HIGH
TEMPERATURES FOR THE SOUTHERN INTERIOR VALLEYS WILL BE A MUCH AS
20 DEGREES COOLER THAN TODAY. A SECOND SYSTEM WILL MOVE IN FROM
THE NORTHWEST LATER IN THE WEEK...BUT THE MODELS DISAGREE ON THE
EXACT TRAJECTORY. EARLIER MODEL RUNS HAD INDICATED THESE SYSTEMS
WOULD GIVE US A DECENT CHANCE OF SHOWER ACTIVITY AT TIMES FROM
LATE TUESDAY THROUGH THE END OF THE WEEK...ESPECIALLY ACROSS
HIGHER TERRAIN. BUT RECENT MODEL TRENDS HAVE BEEN FOR LESS PRECIP
AND SO SLIGHT CHANCE POPS THIS WEEK ARE PROBABLY SUFFICIENT.

&&

.AVIATION...AS OF 5:15 PM PDT SUNDAY...SATELLITE IMAGERY SHOWS
A LEISURELY PROGRESSION OF MARINE STRATUS ONSHORE ALREADY THIS
AFTERNOON. KMRY KSNS AND KWVI ARE/WILL SHORTLY BE UNDER THE
STRATUS LAYER THROUGH LATE MORNING MONDAY. ELSEWHERE... THE MARINE
STRATUS IS CREEPING ONSHORE ALONG THE ENTIRE COASTLINE.
PROGRESSION IS LIKELY TO STALL FOR A TIME AS THE MARINE AIR MASS
INTERACTS WITH A LESS ACCOMMODATING AIR MASS ONSHORE. THIS SHOULD
KEEP THE BAY AREA TERMINALS IN VFR CONDITIONS FOR A FEW MORE HOURS...
WITH SLIGHTLY INCREASING ODDS OF STRATUS BREAKING THROUGH WITH EACH
PROGRESSIVE HOUR. OVERALL... HIGH CONFIDENCE ON STRATUS THIS
EVENING... LOW CONFIDENCE ON PRECISE TIMING.

VICINITY OF KSFO... SAN BRUNO GAP CAM LOOKS OMINOUS WITH MARINE
STRATUS CLEARLY PRESENT. EXPECT TO SEE VFR THROUGH AT LEAST 03Z
WITH MVFR/IFR LIKELY BY NO LATER THAN 07Z. WILL KEEP WATCH FOR
ARRIVALS BETWEEN 04-07Z AND UPGRADE THE TAF AS NECESSARY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CIGS MVFR DETERIORATING TO IFR
OVERNIGHT. SLIGHT RISK OF LIFR VISBYS AROUND SUNRISE.

&&

.MARINE...AS OF 8:46 PM PDT SUNDAY...MARINE LAYER WILL BE PRESENT
OVER THE COASTAL WATERS INTO TOMORROW LEADING TO AREAS OF PATCHY
FOG ALONG THE COAST. WINDS WILL BE PREDOMINATELY LIGHT AND OUT OF
THE NORTHWEST WITH GENTLE SEAS THROUGH THE NEXT 24 HOURS. THE
PATTERN SHIFTS BY TUESDAY WITH INCREASING WINDS AND BUILDING SEAS.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...NONE.

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 200014
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
514 PM PDT SUN APR 19 2015

.SYNOPSIS...COOL CONDITIONS EXPECTED THROUGH TOMORROW 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 3:00 PM PDT SUNDAY...A DEEPER MARINE LAYER
PLUS A STRONGER ONSHORE FLOW AT THE SURFACE HAS LEAD TO COOLER
TEMPERATURES TODAY. CURRENTLY MOST PLACES ARE RUNNING 3 TO 7
DEGREES BEHIND SATURDAY. SHOULD END UP WITH HIGHS IN THE UPPER 50S
TO MID 60S AT THE COAST WITH 70S TO LOWER 80S INLAND. WITH THE
MARINE LAYER EXPECTED TO STAY OVER 2000 FEET TONIGHT AND AN
ONSHORE PUSH AT THE SURFACE...SHOULD SEE ANOTHER ROUND OF CLOUDS
AND PATCHY FOG AROUND THE COAST PLUS INLAND VALLEYS.

TEMPERATURES WILL COOL THROUGH THE WEEK AS A LONGWAVE TROF
ADVANCE TO THE PACNW/BC COASTLINE WHILE AN ASSOCIATED UPPER LEVEL
LOW DROPS DOWN FROM THE NORTH. THIS FEATURE WILL BE WEST OF OUR
COASTAL WATERS BY TUESDAY NIGHT AND WELL TO OUR SW BY WEDNESDAY
EVENING. LAST WEEK THERE WAS CONCERN THAT THE LOW WOULD BRING
SHOWERS TO OUR REGION ALONG WITH POSSIBLE THUNDERSTORMS.
HOWEVER...ALL MODELS ARE IN GOOD AGREEMENT THAT ALMOST ALL OF THE
ASSOCIATED MOISTURE WILL STAY OUT OF OUR AREA. WILL KEEP A MENTION
OF A FEW SHOWERS GOING AS THE ATMOSPHERE WILL BE DESTABILIZED SO
THEY CANNOT BE ENTIRELY RULED OUT. COULD ALSO SEE SOME DRIZZLE
MAINLY ALONG THE COAST. TEMPS WILL RANGE FROM MID 50S TO MID 60S
AT THE COAST WITH MID 60S TO MID 70S FOR INLAND SPOTS. THE COOLER
AND UNSETTLED PATTERN WILL CONTINUE THROUGH AT LEAST SATURDAY.

ECMWF AND GFS SPLIT FOR NEXT WEEK AS THE GFS HAS A LONGWAVE TROF
MOVING INTO OUR AREA BY NEXT MONDAY WHILE THE ECMWF KEEPS ALMOST
ALL OF THE MOISTURE TO OUR NORTH. 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
BOTH INDICATE WETTER THAN NORMAL WEATHER...SO WE COULD POSSIBLY
SEE APRIL ENDING ON A WET NOTE.

&&

.AVIATION...AS OF 5:15 PM PDT SUNDAY...SATELLITE IMAGERY SHOWS
A LEISURELY PROGRESSION OF MARINE STRATUS ONSHORE ALREADY THIS
AFTERNOON. KMRY KSNS AND KWVI ARE/WILL SHORTLY BE UNDER THE
STRATUS LAYER THROUGH LATE MORNING MONDAY. ELSEWHERE... THE MARINE
STRATUS IS CREEPING ONSHORE ALONG THE ENTIRE COASTLINE.
PROGRESSION IS LIKELY TO STALL FOR A TIME AS THE MARINE AIR MASS
INTERACTS WITH A LESS ACCOMMODATING AIR MASS ONSHORE. THIS SHOULD
KEEP THE BAY AREA TERMINALS IN VFR CONDITIONS FOR A FEW MORE HOURS...
WITH SLIGHTLY INCREASING ODDS OF STRATUS BREAKING THROUGH WITH EACH
PROGRESSIVE HOUR. OVERALL... HIGH CONFIDENCE ON STRATUS THIS
EVENING... LOW CONFIDENCE ON PRECISE TIMING.

VICINITY OF KSFO... SAN BRUNO GAP CAM LOOKS OMINOUS WITH MARINE
STRATUS CLEARLY PRESENT. EXPECT TO SEE VFR THROUGH AT LEAST 03Z
WITH MVFR/IFR LIKELY BY NO LATER THAN 07Z. WILL KEEP WATCH FOR
ARRIVALS BETWEEN 04-07Z AND UPGRADE THE TAF AS NECESSARY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CIGS MVFR DETERIORATING TO IFR
OVERNIGHT. SLIGHT RISK OF LIFR VISBYS AROUND SUNRISE.

&&

.MARINE...AS OF 3:00 PM PDT SUNDAY...A MODERATELY DEEP MARINE
LAYER WILL CONTINUE OVER THE COASTAL WATERS THROUGH EARLY IN THE
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...
     .TNGT...NONE.

$$

PUBLIC FORECAST: BELL
AVIATION: DRP
MARINE: SIMS

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 200014
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
514 PM PDT SUN APR 19 2015

.SYNOPSIS...COOL CONDITIONS EXPECTED THROUGH TOMORROW 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 3:00 PM PDT SUNDAY...A DEEPER MARINE LAYER
PLUS A STRONGER ONSHORE FLOW AT THE SURFACE HAS LEAD TO COOLER
TEMPERATURES TODAY. CURRENTLY MOST PLACES ARE RUNNING 3 TO 7
DEGREES BEHIND SATURDAY. SHOULD END UP WITH HIGHS IN THE UPPER 50S
TO MID 60S AT THE COAST WITH 70S TO LOWER 80S INLAND. WITH THE
MARINE LAYER EXPECTED TO STAY OVER 2000 FEET TONIGHT AND AN
ONSHORE PUSH AT THE SURFACE...SHOULD SEE ANOTHER ROUND OF CLOUDS
AND PATCHY FOG AROUND THE COAST PLUS INLAND VALLEYS.

TEMPERATURES WILL COOL THROUGH THE WEEK AS A LONGWAVE TROF
ADVANCE TO THE PACNW/BC COASTLINE WHILE AN ASSOCIATED UPPER LEVEL
LOW DROPS DOWN FROM THE NORTH. THIS FEATURE WILL BE WEST OF OUR
COASTAL WATERS BY TUESDAY NIGHT AND WELL TO OUR SW BY WEDNESDAY
EVENING. LAST WEEK THERE WAS CONCERN THAT THE LOW WOULD BRING
SHOWERS TO OUR REGION ALONG WITH POSSIBLE THUNDERSTORMS.
HOWEVER...ALL MODELS ARE IN GOOD AGREEMENT THAT ALMOST ALL OF THE
ASSOCIATED MOISTURE WILL STAY OUT OF OUR AREA. WILL KEEP A MENTION
OF A FEW SHOWERS GOING AS THE ATMOSPHERE WILL BE DESTABILIZED SO
THEY CANNOT BE ENTIRELY RULED OUT. COULD ALSO SEE SOME DRIZZLE
MAINLY ALONG THE COAST. TEMPS WILL RANGE FROM MID 50S TO MID 60S
AT THE COAST WITH MID 60S TO MID 70S FOR INLAND SPOTS. THE COOLER
AND UNSETTLED PATTERN WILL CONTINUE THROUGH AT LEAST SATURDAY.

ECMWF AND GFS SPLIT FOR NEXT WEEK AS THE GFS HAS A LONGWAVE TROF
MOVING INTO OUR AREA BY NEXT MONDAY WHILE THE ECMWF KEEPS ALMOST
ALL OF THE MOISTURE TO OUR NORTH. 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
BOTH INDICATE WETTER THAN NORMAL WEATHER...SO WE COULD POSSIBLY
SEE APRIL ENDING ON A WET NOTE.

&&

.AVIATION...AS OF 5:15 PM PDT SUNDAY...SATELLITE IMAGERY SHOWS
A LEISURELY PROGRESSION OF MARINE STRATUS ONSHORE ALREADY THIS
AFTERNOON. KMRY KSNS AND KWVI ARE/WILL SHORTLY BE UNDER THE
STRATUS LAYER THROUGH LATE MORNING MONDAY. ELSEWHERE... THE MARINE
STRATUS IS CREEPING ONSHORE ALONG THE ENTIRE COASTLINE.
PROGRESSION IS LIKELY TO STALL FOR A TIME AS THE MARINE AIR MASS
INTERACTS WITH A LESS ACCOMMODATING AIR MASS ONSHORE. THIS SHOULD
KEEP THE BAY AREA TERMINALS IN VFR CONDITIONS FOR A FEW MORE HOURS...
WITH SLIGHTLY INCREASING ODDS OF STRATUS BREAKING THROUGH WITH EACH
PROGRESSIVE HOUR. OVERALL... HIGH CONFIDENCE ON STRATUS THIS
EVENING... LOW CONFIDENCE ON PRECISE TIMING.

VICINITY OF KSFO... SAN BRUNO GAP CAM LOOKS OMINOUS WITH MARINE
STRATUS CLEARLY PRESENT. EXPECT TO SEE VFR THROUGH AT LEAST 03Z
WITH MVFR/IFR LIKELY BY NO LATER THAN 07Z. WILL KEEP WATCH FOR
ARRIVALS BETWEEN 04-07Z AND UPGRADE THE TAF AS NECESSARY.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...CIGS MVFR DETERIORATING TO IFR
OVERNIGHT. SLIGHT RISK OF LIFR VISBYS AROUND SUNRISE.

&&

.MARINE...AS OF 3:00 PM PDT SUNDAY...A MODERATELY DEEP MARINE
LAYER WILL CONTINUE OVER THE COASTAL WATERS THROUGH EARLY IN THE
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...
     .TNGT...NONE.

$$

PUBLIC FORECAST: BELL
AVIATION: DRP
MARINE: SIMS

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 192154
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
254 PM PDT SUN APR 19 2015

.SYNOPSIS...COOL CONDITIONS EXPECTED THROUGH TOMORROW 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 3:00 PM PDT SUNDAY...A DEEPER MARINE LAYER
PLUS A STRONGER ONSHORE FLOW AT THE SURFACE HAS LEAD TO COOLER
TEMPERATURES TODAY. CURRENTLY MOST PLACES ARE RUNNING 3 TO 7
DEGREES BEHIND SATURDAY. SHOULD END UP WITH HIGHS IN THE UPPER 50S
TO MID 60S AT THE COAST WITH 70S TO LOWER 80S INLAND. WITH THE
MARINE LAYER EXPECTED TO STAY OVER 2000 FEET TONIGHT AND AN
ONSHORE PUSH AT THE SURFACE...SHOULD SEE ANOTHER ROUND OF CLOUDS
AND PATCHY FOG AROUND THE COAST PLUS INLAND VALLEYS.

TEMPERATURES WILL COOL THROUGH THE WEEK AS A LONGWAVE TROF
ADVANCE TO THE PACNW/BC COASTLINE WHILE AN ASSOCIATED UPPER LEVEL
LOW DROPS DOWN FROM THE NORTH. THIS FEATURE WILL BE WEST OF OUR
COASTAL WATERS BY TUESDAY NIGHT AND WELL TO OUR SW BY WEDNESDAY
EVENING. LAST WEEK THERE WAS CONCERN THAT THE LOW WOULD BRING
SHOWERS TO OUR REGION ALONG WITH POSSIBLE THUNDERSTORMS.
HOWEVER...ALL MODELS ARE IN GOOD AGREEMENT THAT ALMOST ALL OF THE
ASSOCIATED MOISTURE WILL STAY OUT OF OUR AREA. WILL KEEP A MENTION
OF A FEW SHOWERS GOING AS THE ATMOSPHERE WILL BE DESTABILIZED SO
THEY CANNOT BE ENTIRELY RULED OUT. COULD ALSO SEE SOME DRIZZLE
MAINLY ALONG THE COAST. TEMPS WILL RANGE FROM MID 50S TO MID 60S
AT THE COAST WITH MID 60S TO MID 70S FOR INLAND SPOTS. THE COOLER
AND UNSETTLED PATTERN WILL CONTINUE THROUGH AT LEAST SATURDAY.

ECMWF AND GFS SPLIT FOR NEXT WEEK AS THE GFS HAS A LONGWAVE TROF
MOVING INTO OUR AREA BY NEXT MONDAY WHILE THE ECMWF KEEPS ALMOST
ALL OF THE MOISTURE TO OUR NORTH. 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
BOTH INDICATE WETTER THAN NORMAL WEATHER...SO WE COULD POSSIBLY
SEE APRIL ENDING ON A WET NOTE.

&&

.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 3:00 PM PDT SUNDAY...A MODERATELY DEEP MARINE
LAYER WILL CONTINUE OVER THE COASTAL WATERS THROUGH EARLY IN THE
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...
     .TNGT...NONE.

$$

PUBLIC FORECAST: BELL
AVIATION/MARINE: SIMS

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






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

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







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

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA








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

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







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

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA








000
FXUS66 KMTR 191549
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
849 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 4:53 AM PDT SUNDAY...A CLOSED AND DRY MID LEVEL
LOW 150 MILES WEST OF POINT ARENA THIS MORNING WILL DRIFT SOUTH
DURING THE PERIOD. PLENTY OF STRATUS AND FOG HAVE MOVED INLAND
ALREADY AT THIS HOUR. LITTLE CHANGE IN THE LOWER LEVEL TEMPERATURES
...LIGHT SURFACE WINDS AND SPECIFICALLY A LACK OF NORTHERLY WINDS
THROUGH MONDAY EVENING FAVOR A CONTINUATION OF THE MARINE LAYER. A
FEW POCKETS OF MOSTLY LIGHT DRIZZLE ALONG THE IMMEDIATE COAST AND
NEAR THE BAY WATERS CAN BE EXPECTED DUE TO A DEEPENING MARINE LAYER.

VICINITY OF KSFO...IFR CIG TIL 18Z THEN VFR FOR THE AFTERNOON AND
EVENING. MOSTLY LIGHT WINDS TODAY. STRATUS RETURNS TONIGHT. LOW TO
MODERATE CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR TIL 17Z-18Z TODAY THEN VFR. LOW
CONFIDENCE ON CLEARING TIMES TODAY. STRATUS LIKELY RETURNING EARLY
THIS EVENING.

&&

.MARINE...AS OF 8:45 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: CANEPA
MARINE: SIMS

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 191549
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
849 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 4:53 AM PDT SUNDAY...A CLOSED AND DRY MID LEVEL
LOW 150 MILES WEST OF POINT ARENA THIS MORNING WILL DRIFT SOUTH
DURING THE PERIOD. PLENTY OF STRATUS AND FOG HAVE MOVED INLAND
ALREADY AT THIS HOUR. LITTLE CHANGE IN THE LOWER LEVEL TEMPERATURES
...LIGHT SURFACE WINDS AND SPECIFICALLY A LACK OF NORTHERLY WINDS
THROUGH MONDAY EVENING FAVOR A CONTINUATION OF THE MARINE LAYER. A
FEW POCKETS OF MOSTLY LIGHT DRIZZLE ALONG THE IMMEDIATE COAST AND
NEAR THE BAY WATERS CAN BE EXPECTED DUE TO A DEEPENING MARINE LAYER.

VICINITY OF KSFO...IFR CIG TIL 18Z THEN VFR FOR THE AFTERNOON AND
EVENING. MOSTLY LIGHT WINDS TODAY. STRATUS RETURNS TONIGHT. LOW TO
MODERATE CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR TIL 17Z-18Z TODAY THEN VFR. LOW
CONFIDENCE ON CLEARING TIMES TODAY. STRATUS LIKELY RETURNING EARLY
THIS EVENING.

&&

.MARINE...AS OF 8:45 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: CANEPA
MARINE: SIMS

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 191208 CCA
AFDMTR

AREA FORECAST DISCUSSION...CORRECTED AVIATION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
503 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 04:05 AM PDT SUNDAY...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 4:53 AM PDT SUNDAY...A CLOSED AND DRY MID LEVEL
LOW 150 MILES WEST OF POINT ARENA THIS MORNING WILL DRIFT SOUTH
DURING THE PERIOD. PLENTY OF STRATUS AND FOG HAVE MOVED INLAND
ALREADY AT THIS HOUR. LITTLE CHANGE IN THE LOWER LEVEL TEMPERATURES
...LIGHT SURFACE WINDS AND SPECIFICALLY A LACK OF NORTHERLY WINDS
THROUGH MONDAY EVENING FAVOR A CONTINUATION OF THE MARINE LAYER. A
FEW POCKETS OF MOSTLY LIGHT DRIZZLE ALONG THE IMMEDIATE COAST AND
NEAR THE BAY WATERS CAN BE EXPECTED DUE TO A DEEPENING MARINE LAYER.

VICINITY OF KSFO...IFR CIG TIL 18Z THEN VFR FOR THE AFTERNOON AND
EVENING. MOSTLY LIGHT WINDS TODAY. STRATUS RETURNS TONIGHT. LOW TO
MODERATE CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR TIL 17Z-18Z TODAY THEN VFR. LOW
CONFIDENCE ON CLEARING TIMES TODAY. STRATUS LIKELY RETURNING EARLY
THIS EVENING.

&&

.MARINE...AS OF 4:05 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: RGASS
AVIATION/MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA










000
FXUS66 KMTR 191208 CCA
AFDMTR

AREA FORECAST DISCUSSION...CORRECTED AVIATION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
503 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 04:05 AM PDT SUNDAY...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 4:53 AM PDT SUNDAY...A CLOSED AND DRY MID LEVEL
LOW 150 MILES WEST OF POINT ARENA THIS MORNING WILL DRIFT SOUTH
DURING THE PERIOD. PLENTY OF STRATUS AND FOG HAVE MOVED INLAND
ALREADY AT THIS HOUR. LITTLE CHANGE IN THE LOWER LEVEL TEMPERATURES
...LIGHT SURFACE WINDS AND SPECIFICALLY A LACK OF NORTHERLY WINDS
THROUGH MONDAY EVENING FAVOR A CONTINUATION OF THE MARINE LAYER. A
FEW POCKETS OF MOSTLY LIGHT DRIZZLE ALONG THE IMMEDIATE COAST AND
NEAR THE BAY WATERS CAN BE EXPECTED DUE TO A DEEPENING MARINE LAYER.

VICINITY OF KSFO...IFR CIG TIL 18Z THEN VFR FOR THE AFTERNOON AND
EVENING. MOSTLY LIGHT WINDS TODAY. STRATUS RETURNS TONIGHT. LOW TO
MODERATE CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR TIL 17Z-18Z TODAY THEN VFR. LOW
CONFIDENCE ON CLEARING TIMES TODAY. STRATUS LIKELY RETURNING EARLY
THIS EVENING.

&&

.MARINE...AS OF 4:05 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: RGASS
AVIATION/MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA









000
FXUS66 KMTR 191208 CCA
AFDMTR

AREA FORECAST DISCUSSION...CORRECTED AVIATION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
503 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 04:05 AM PDT SUNDAY...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 4:53 AM PDT SUNDAY...A CLOSED AND DRY MID LEVEL
LOW 150 MILES WEST OF POINT ARENA THIS MORNING WILL DRIFT SOUTH
DURING THE PERIOD. PLENTY OF STRATUS AND FOG HAVE MOVED INLAND
ALREADY AT THIS HOUR. LITTLE CHANGE IN THE LOWER LEVEL TEMPERATURES
...LIGHT SURFACE WINDS AND SPECIFICALLY A LACK OF NORTHERLY WINDS
THROUGH MONDAY EVENING FAVOR A CONTINUATION OF THE MARINE LAYER. A
FEW POCKETS OF MOSTLY LIGHT DRIZZLE ALONG THE IMMEDIATE COAST AND
NEAR THE BAY WATERS CAN BE EXPECTED DUE TO A DEEPENING MARINE LAYER.

VICINITY OF KSFO...IFR CIG TIL 18Z THEN VFR FOR THE AFTERNOON AND
EVENING. MOSTLY LIGHT WINDS TODAY. STRATUS RETURNS TONIGHT. LOW TO
MODERATE CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR TIL 17Z-18Z TODAY THEN VFR. LOW
CONFIDENCE ON CLEARING TIMES TODAY. STRATUS LIKELY RETURNING EARLY
THIS EVENING.

&&

.MARINE...AS OF 4:05 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: RGASS
AVIATION/MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA










000
FXUS66 KMTR 191208 CCA
AFDMTR

AREA FORECAST DISCUSSION...CORRECTED AVIATION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
503 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 04:05 AM PDT SUNDAY...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 4:53 AM PDT SUNDAY...A CLOSED AND DRY MID LEVEL
LOW 150 MILES WEST OF POINT ARENA THIS MORNING WILL DRIFT SOUTH
DURING THE PERIOD. PLENTY OF STRATUS AND FOG HAVE MOVED INLAND
ALREADY AT THIS HOUR. LITTLE CHANGE IN THE LOWER LEVEL TEMPERATURES
...LIGHT SURFACE WINDS AND SPECIFICALLY A LACK OF NORTHERLY WINDS
THROUGH MONDAY EVENING FAVOR A CONTINUATION OF THE MARINE LAYER. A
FEW POCKETS OF MOSTLY LIGHT DRIZZLE ALONG THE IMMEDIATE COAST AND
NEAR THE BAY WATERS CAN BE EXPECTED DUE TO A DEEPENING MARINE LAYER.

VICINITY OF KSFO...IFR CIG TIL 18Z THEN VFR FOR THE AFTERNOON AND
EVENING. MOSTLY LIGHT WINDS TODAY. STRATUS RETURNS TONIGHT. LOW TO
MODERATE CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR TIL 17Z-18Z TODAY THEN VFR. LOW
CONFIDENCE ON CLEARING TIMES TODAY. STRATUS LIKELY RETURNING EARLY
THIS EVENING.

&&

.MARINE...AS OF 4:05 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: RGASS
AVIATION/MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA









000
FXUS66 KMTR 191203
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
503 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 04:05 AM PDT SUNDAY...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 4:53 AM PDT SUNDAY...A CLOSED AND DRY MID LEVEL
LOW 150 MILES WEST OF POINT ARENA THIS MORNING WILL DRIFT SOUTH
DURING THE PERIOD. PLENTY OF STRATUS AND FOG HAVE MOVED INLAND
ALREADY AT THIS HOUR. LITTLE CHANGE IN THE LOWER LEVEL TEMPERATURES
...LIGHT SURFACE WINDS AND SPECIFICALLY A LACK OF NORTHERLY WINDS
THROUGH MONDAY EVENING FAVOR A CONTINUATION OF THE MARINE LAYER. A
FEW POCKETS OF MOSTLY LIGHT DRIZZLE ALONG THE IMMEDIATE COAST AND
NEAR THE BAY WATERS CAN BE EXPECTED DUE TO A DEEPENING MARINE LAYER.

VICINITY OF KSFO...IFR CIG TIL 18Z THEN VFR FOR THE AFTERNOON AND
EVENING. MOSTLY LIGHT WINDS TODAY. STRATUS RETURNS TONIGHT. LOW TO
MODERATE CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR TIL 17Z-18Z TODAY THEN VFR. STRATUS
LIKELY RETURNING EARLY THIS EVENING. LOW CONFIDENCE.

&&

.MARINE...AS OF 4:05 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: RGASS
AVIATION/MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 191203
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
503 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 04:05 AM PDT SUNDAY...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 4:53 AM PDT SUNDAY...A CLOSED AND DRY MID LEVEL
LOW 150 MILES WEST OF POINT ARENA THIS MORNING WILL DRIFT SOUTH
DURING THE PERIOD. PLENTY OF STRATUS AND FOG HAVE MOVED INLAND
ALREADY AT THIS HOUR. LITTLE CHANGE IN THE LOWER LEVEL TEMPERATURES
...LIGHT SURFACE WINDS AND SPECIFICALLY A LACK OF NORTHERLY WINDS
THROUGH MONDAY EVENING FAVOR A CONTINUATION OF THE MARINE LAYER. A
FEW POCKETS OF MOSTLY LIGHT DRIZZLE ALONG THE IMMEDIATE COAST AND
NEAR THE BAY WATERS CAN BE EXPECTED DUE TO A DEEPENING MARINE LAYER.

VICINITY OF KSFO...IFR CIG TIL 18Z THEN VFR FOR THE AFTERNOON AND
EVENING. MOSTLY LIGHT WINDS TODAY. STRATUS RETURNS TONIGHT. LOW TO
MODERATE CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR TIL 17Z-18Z TODAY THEN VFR. STRATUS
LIKELY RETURNING EARLY THIS EVENING. LOW CONFIDENCE.

&&

.MARINE...AS OF 4:05 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: RGASS
AVIATION/MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA






000
FXUS66 KMTR 191203
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
503 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 04:05 AM PDT SUNDAY...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 4:53 AM PDT SUNDAY...A CLOSED AND DRY MID LEVEL
LOW 150 MILES WEST OF POINT ARENA THIS MORNING WILL DRIFT SOUTH
DURING THE PERIOD. PLENTY OF STRATUS AND FOG HAVE MOVED INLAND
ALREADY AT THIS HOUR. LITTLE CHANGE IN THE LOWER LEVEL TEMPERATURES
...LIGHT SURFACE WINDS AND SPECIFICALLY A LACK OF NORTHERLY WINDS
THROUGH MONDAY EVENING FAVOR A CONTINUATION OF THE MARINE LAYER. A
FEW POCKETS OF MOSTLY LIGHT DRIZZLE ALONG THE IMMEDIATE COAST AND
NEAR THE BAY WATERS CAN BE EXPECTED DUE TO A DEEPENING MARINE LAYER.

VICINITY OF KSFO...IFR CIG TIL 18Z THEN VFR FOR THE AFTERNOON AND
EVENING. MOSTLY LIGHT WINDS TODAY. STRATUS RETURNS TONIGHT. LOW TO
MODERATE CONFIDENCE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR TIL 17Z-18Z TODAY THEN VFR. STRATUS
LIKELY RETURNING EARLY THIS EVENING. LOW CONFIDENCE.

&&

.MARINE...AS OF 4:05 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: RGASS
AVIATION/MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA







000
FXUS66 KMTR 191106
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
406 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 04:05 AM PDT SUNDAY...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 9:00 PM PDT SATURDAY...THE MARINE LAYER WAS
DEEPENING ON SATURDAY EVENING AND TERMINALS NEAR MONTEREY BAY WERE
EXPERIENCING IFR CONDITIONS. ONSHORE FLOW REMAINS RELATIVELY WEAK
AND SO LOW CLOUDS THUS FAR BEEN SLOW TO DEVELOP IN SF BAY. GIVEN
THE INCREASING DEPTH OF THE MARINE LAYER FEEL IT`S LIKELY THERE
WILL BE IFR/MVFR CIGS AROUND MUCH OF SF BAY BY LATE TONIGHT.
A DEEPER MARINE LAYER SHOULD MEAN LATER CLEARING ON SUNDAY...BUT
BOTH THE NAM AND WRF MODELS SHOW LIGHT EASTERLY FLOW DEVELOPING
NEAR THE TOP OF THE MARINE LAYER WHICH MAY HASTEN CLEARING ON
SUNDAY MORNING. THEREFORE...CONFIDENCE IS LOW REGARDING CLEARING
TIMES ON SUNDAY MORNING.

VICINITY OF KSFO...VFR CONDITIONS LIKELY THROUGH ABOUT 08Z WITH
IFR/MVFR CIGS LIKELY TO DEVELOP SOMETIME BETWEEN 08Z AND 12Z. LOW
CIGS EXPECTED TO CLEAR BY 18Z SUNDAY MORNING. CONFIDENCE LOW
REGARDING TIMING OF LOW CIG ONSET AND CLEARING. LIGHT WEST WINDS
OVERNIGHT AND INTO SUNDAY MORNING...INCREASING TO ABOUT 15 KNOTS
SUNDAY AFTERNOON.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS THROUGH ABOUT 17-18Z SUNDAY
WITH VFR CONDITIONS THEREAFTER. LIGHT WESTERLY WINDS.

&&

.MARINE...AS OF 04:05 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: RGASS
AVIATION: DYKEMA
MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 191106
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
406 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 04:05 AM PDT SUNDAY...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 9:00 PM PDT SATURDAY...THE MARINE LAYER WAS
DEEPENING ON SATURDAY EVENING AND TERMINALS NEAR MONTEREY BAY WERE
EXPERIENCING IFR CONDITIONS. ONSHORE FLOW REMAINS RELATIVELY WEAK
AND SO LOW CLOUDS THUS FAR BEEN SLOW TO DEVELOP IN SF BAY. GIVEN
THE INCREASING DEPTH OF THE MARINE LAYER FEEL IT`S LIKELY THERE
WILL BE IFR/MVFR CIGS AROUND MUCH OF SF BAY BY LATE TONIGHT.
A DEEPER MARINE LAYER SHOULD MEAN LATER CLEARING ON SUNDAY...BUT
BOTH THE NAM AND WRF MODELS SHOW LIGHT EASTERLY FLOW DEVELOPING
NEAR THE TOP OF THE MARINE LAYER WHICH MAY HASTEN CLEARING ON
SUNDAY MORNING. THEREFORE...CONFIDENCE IS LOW REGARDING CLEARING
TIMES ON SUNDAY MORNING.

VICINITY OF KSFO...VFR CONDITIONS LIKELY THROUGH ABOUT 08Z WITH
IFR/MVFR CIGS LIKELY TO DEVELOP SOMETIME BETWEEN 08Z AND 12Z. LOW
CIGS EXPECTED TO CLEAR BY 18Z SUNDAY MORNING. CONFIDENCE LOW
REGARDING TIMING OF LOW CIG ONSET AND CLEARING. LIGHT WEST WINDS
OVERNIGHT AND INTO SUNDAY MORNING...INCREASING TO ABOUT 15 KNOTS
SUNDAY AFTERNOON.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS THROUGH ABOUT 17-18Z SUNDAY
WITH VFR CONDITIONS THEREAFTER. LIGHT WESTERLY WINDS.

&&

.MARINE...AS OF 04:05 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: RGASS
AVIATION: DYKEMA
MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 190401
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
901 PM PDT SAT APR 18 2015

.SYNOPSIS...A PERSISTENT MARINE LAYER ALONG THE COAST WILL
RESULT IN COOLER TEMPS NEAR THE OCEAN WHILE INLAND TEMPERATURES
REMAIN ABOVE AVERAGE THROUGH SUNDAY. WEAK UPPER LEVEL WEATHER
DISTURBANCES WILL BRING COOLER WEATHER...ALONG WITH SLIGHT SHOWER
AND THUNDERSTORM CHANCES...TO THE REGION FOR MUCH OF THE UPCOMING
WEEK.

&&

.DISCUSSION...AS OF 9:00 PM PDT SATURDAY...A SLIGHTLY DEEPER
MARINE LAYER AND INCREASE IN ONSHORE FLOW RESULTED IN COOLER
CONDITIONS NEAR THE OCEAN...AROUND SF BAY...AND IN THE COASTAL
VALLEYS TODAY. THE INLAND VALLEYS AND HILLS REMAINED WARM...WITH
AFTERNOON HIGHS AS MUCH AS TEN DEGREES ABOVE AVERAGE FOR MID-
APRIL.

EVENING WATER VAPOR SATELLITE IMAGERY SHOWS A WEAK UPPER LEVEL
DISTURBANCE DROPPING SOUTH ALONG THE WEST COAST. THIS DISTURBANCE
TRIGGERED ISOLATED THUNDERSTORM ACTIVITY ACROSS THE HIGHER
MOUNTAINS OF NORTHWEST CA AND THE FAR NORTHERN SIERRA NEVADA THIS
AFTERNOON. IN THE SHORT-TERM...AS THE WEAK UPPER LEVEL DISTURBANCE
CONTINUES TO DROP SOUTH OFFSHORE...IT APPEARS THAT MOISTURE AND
INSTABILITY NECESSARY FOR CONVECTION INITIATION WILL ONLY OCCUR
ACROSS THE HIGHER MOUNTAINS OF NORTHERN AND CENTRAL CA...AND NOT
OVER OUR FORECAST AREA. THE ONE EXCEPTION MAY BE THE HIGHER
MOUNTAINS OF SOUTHERN SAN BENITO COUNTY WHERE THE 00Z NAM
FORECASTS AFTERNOON AND EVENING CONVECTIVE PRECIP LATE TOMORROW
AND AGAIN LATE ON MONDAY. CURRENT FORECAST INCLUDES A SLIGHT
CHANCE OF THUNDERSTORMS IN THAT AREA FOR LATE MONDAY...BUT NOT
TOMORROW. MAY NEED TO ADD THUNDERSTORM CHANCES FOR SOUTHERN SAN
BENITO COUNTY LATE TOMORROW IF OTHER 00Z MODEL DATA SUPPORTS THE
00Z NAM IN THIS REGARD. THE CHANCE FOR CONVECTION OVER OUR
SOUTHERNMOST MOUNTAINS APPEARS HIGHER ON TUESDAY WHEN THE 18Z GFS
FORECASTS WIDESPREAD LATE AFTERNOON AND EARLY EVENING
PRECIPITATION ACROSS THE HIGHER TERRAIN OF MONTEREY AND SAN BENITO
COUNTIES.

FORT ORD PROFILER DATA SHOWS THE MARINE LAYER HAS BEEN DEEPENING
SINCE THIS AFTERNOON...LIKELY IN RESPONSE TO THE APPROACHING UPPER
LEVEL DISTURBANCE. A DEEPER MARINE LAYER SHOULD RESULT IN
MORE WIDESPREAD LOW CLOUD COVER ON SUNDAY MORNING...AND COOLER
CONDITIONS FOR THOSE INLAND AREAS THAT REMAINED WARM TODAY. THE
COOLING TREND WILL CONTINUE INTO MONDAY. INLAND AREAS WILL BE MUCH
COOLER BY TUESDAY WHEN AN UPPER TROUGH APPROACHES FROM THE
NORTHWEST AND TRIGGERS AN INCREASE IN ONSHORE FLOW. THAT UPPER
TROUGH MAY ALSO TRIGGER SCATTERED SHOWER ACTIVITY ACROSS OUR AREA
ON TUESDAY AND WEDNESDAY...ALTHOUGH MODELS ONCE AGAIN INDICATE
THAT MOST PRECIP AROUND MIDWEEK WILL REMAIN OVER THE HIGHER MOUNTAINS.

THE MEDIUM RANGE MODELS CONTINUE TO INDICATE THE POSSIBILITY OF
MORE WIDESPREAD PRECIPITATION LATER NEXT WEEK AS A SYSTEM WITH
POTENTIALLY MORE MOISTURE MOVES IN FROM THE NORTHWEST.

&&

.AVIATION...AS OF 9:00 PM PDT SATURDAY...THE MARINE LAYER WAS
DEEPENING ON SATURDAY EVENING AND TERMINALS NEAR MONTEREY BAY WERE
EXPERIENCING IFR CONDITIONS. ONSHORE FLOW REMAINS RELATIVELY WEAK
AND SO LOW CLOUDS THUS FAR BEEN SLOW TO DEVELOP IN SF BAY. GIVEN
THE INCREASING DEPTH OF THE MARINE LAYER FEEL IT`S LIKELY THERE
WILL BE IFR/MVFR CIGS AROUND MUCH OF SF BAY BY LATE TONIGHT.
A DEEPER MARINE LAYER SHOULD MEAN LATER CLEARING ON SUNDAY...BUT
BOTH THE NAM AND WRF MODELS SHOW LIGHT EASTERLY FLOW DEVELOPING
NEAR THE TOP OF THE MARINE LAYER WHICH MAY HASTEN CLEARING ON
SUNDAY MORNING. THEREFORE...CONFIDENCE IS LOW REGARDING CLEARING
TIMES ON SUNDAY MORNING.

VICINITY OF KSFO...VFR CONDITIONS LIKELY THROUGH ABOUT 08Z WITH
IFR/MVFR CIGS LIKELY TO DEVELOP SOMETIME BETWEEN 08Z AND 12Z. LOW
CIGS EXPECTED TO CLEAR BY 18Z SUNDAY MORNING. CONFIDENCE LOW
REGARDING TIMING OF LOW CIG ONSET AND CLEARING. LIGHT WEST WINDS
OVERNIGHT AND INTO SUNDAY MORNING...INCREASING TO ABOUT 15 KNOTS
SUNDAY AFTERNOON.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS THROUGH ABOUT 17-18Z SUNDAY
WITH VFR CONDITIONS THEREAFTER. LIGHT WESTERLY WINDS.

&&

.MARINE...AS OF 8:30 PM PDT SATURDAY...NORTHWEST WINDS AND SEAS
WILL CONTINUE TO SUBSIDE THROUGH TONIGHT AND INTO SUNDAY.
RELATIVELY LIGHT WINDS AND GENTLE SEA CONDITIONS WILL THEN
CONTINUE THROUGH MONDAY. 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...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM UNTIL 9 PM

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: DYKEMA

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 190401
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
901 PM PDT SAT APR 18 2015

.SYNOPSIS...A PERSISTENT MARINE LAYER ALONG THE COAST WILL
RESULT IN COOLER TEMPS NEAR THE OCEAN WHILE INLAND TEMPERATURES
REMAIN ABOVE AVERAGE THROUGH SUNDAY. WEAK UPPER LEVEL WEATHER
DISTURBANCES WILL BRING COOLER WEATHER...ALONG WITH SLIGHT SHOWER
AND THUNDERSTORM CHANCES...TO THE REGION FOR MUCH OF THE UPCOMING
WEEK.

&&

.DISCUSSION...AS OF 9:00 PM PDT SATURDAY...A SLIGHTLY DEEPER
MARINE LAYER AND INCREASE IN ONSHORE FLOW RESULTED IN COOLER
CONDITIONS NEAR THE OCEAN...AROUND SF BAY...AND IN THE COASTAL
VALLEYS TODAY. THE INLAND VALLEYS AND HILLS REMAINED WARM...WITH
AFTERNOON HIGHS AS MUCH AS TEN DEGREES ABOVE AVERAGE FOR MID-
APRIL.

EVENING WATER VAPOR SATELLITE IMAGERY SHOWS A WEAK UPPER LEVEL
DISTURBANCE DROPPING SOUTH ALONG THE WEST COAST. THIS DISTURBANCE
TRIGGERED ISOLATED THUNDERSTORM ACTIVITY ACROSS THE HIGHER
MOUNTAINS OF NORTHWEST CA AND THE FAR NORTHERN SIERRA NEVADA THIS
AFTERNOON. IN THE SHORT-TERM...AS THE WEAK UPPER LEVEL DISTURBANCE
CONTINUES TO DROP SOUTH OFFSHORE...IT APPEARS THAT MOISTURE AND
INSTABILITY NECESSARY FOR CONVECTION INITIATION WILL ONLY OCCUR
ACROSS THE HIGHER MOUNTAINS OF NORTHERN AND CENTRAL CA...AND NOT
OVER OUR FORECAST AREA. THE ONE EXCEPTION MAY BE THE HIGHER
MOUNTAINS OF SOUTHERN SAN BENITO COUNTY WHERE THE 00Z NAM
FORECASTS AFTERNOON AND EVENING CONVECTIVE PRECIP LATE TOMORROW
AND AGAIN LATE ON MONDAY. CURRENT FORECAST INCLUDES A SLIGHT
CHANCE OF THUNDERSTORMS IN THAT AREA FOR LATE MONDAY...BUT NOT
TOMORROW. MAY NEED TO ADD THUNDERSTORM CHANCES FOR SOUTHERN SAN
BENITO COUNTY LATE TOMORROW IF OTHER 00Z MODEL DATA SUPPORTS THE
00Z NAM IN THIS REGARD. THE CHANCE FOR CONVECTION OVER OUR
SOUTHERNMOST MOUNTAINS APPEARS HIGHER ON TUESDAY WHEN THE 18Z GFS
FORECASTS WIDESPREAD LATE AFTERNOON AND EARLY EVENING
PRECIPITATION ACROSS THE HIGHER TERRAIN OF MONTEREY AND SAN BENITO
COUNTIES.

FORT ORD PROFILER DATA SHOWS THE MARINE LAYER HAS BEEN DEEPENING
SINCE THIS AFTERNOON...LIKELY IN RESPONSE TO THE APPROACHING UPPER
LEVEL DISTURBANCE. A DEEPER MARINE LAYER SHOULD RESULT IN
MORE WIDESPREAD LOW CLOUD COVER ON SUNDAY MORNING...AND COOLER
CONDITIONS FOR THOSE INLAND AREAS THAT REMAINED WARM TODAY. THE
COOLING TREND WILL CONTINUE INTO MONDAY. INLAND AREAS WILL BE MUCH
COOLER BY TUESDAY WHEN AN UPPER TROUGH APPROACHES FROM THE
NORTHWEST AND TRIGGERS AN INCREASE IN ONSHORE FLOW. THAT UPPER
TROUGH MAY ALSO TRIGGER SCATTERED SHOWER ACTIVITY ACROSS OUR AREA
ON TUESDAY AND WEDNESDAY...ALTHOUGH MODELS ONCE AGAIN INDICATE
THAT MOST PRECIP AROUND MIDWEEK WILL REMAIN OVER THE HIGHER MOUNTAINS.

THE MEDIUM RANGE MODELS CONTINUE TO INDICATE THE POSSIBILITY OF
MORE WIDESPREAD PRECIPITATION LATER NEXT WEEK AS A SYSTEM WITH
POTENTIALLY MORE MOISTURE MOVES IN FROM THE NORTHWEST.

&&

.AVIATION...AS OF 9:00 PM PDT SATURDAY...THE MARINE LAYER WAS
DEEPENING ON SATURDAY EVENING AND TERMINALS NEAR MONTEREY BAY WERE
EXPERIENCING IFR CONDITIONS. ONSHORE FLOW REMAINS RELATIVELY WEAK
AND SO LOW CLOUDS THUS FAR BEEN SLOW TO DEVELOP IN SF BAY. GIVEN
THE INCREASING DEPTH OF THE MARINE LAYER FEEL IT`S LIKELY THERE
WILL BE IFR/MVFR CIGS AROUND MUCH OF SF BAY BY LATE TONIGHT.
A DEEPER MARINE LAYER SHOULD MEAN LATER CLEARING ON SUNDAY...BUT
BOTH THE NAM AND WRF MODELS SHOW LIGHT EASTERLY FLOW DEVELOPING
NEAR THE TOP OF THE MARINE LAYER WHICH MAY HASTEN CLEARING ON
SUNDAY MORNING. THEREFORE...CONFIDENCE IS LOW REGARDING CLEARING
TIMES ON SUNDAY MORNING.

VICINITY OF KSFO...VFR CONDITIONS LIKELY THROUGH ABOUT 08Z WITH
IFR/MVFR CIGS LIKELY TO DEVELOP SOMETIME BETWEEN 08Z AND 12Z. LOW
CIGS EXPECTED TO CLEAR BY 18Z SUNDAY MORNING. CONFIDENCE LOW
REGARDING TIMING OF LOW CIG ONSET AND CLEARING. LIGHT WEST WINDS
OVERNIGHT AND INTO SUNDAY MORNING...INCREASING TO ABOUT 15 KNOTS
SUNDAY AFTERNOON.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS THROUGH ABOUT 17-18Z SUNDAY
WITH VFR CONDITIONS THEREAFTER. LIGHT WESTERLY WINDS.

&&

.MARINE...AS OF 8:30 PM PDT SATURDAY...NORTHWEST WINDS AND SEAS
WILL CONTINUE TO SUBSIDE THROUGH TONIGHT AND INTO SUNDAY.
RELATIVELY LIGHT WINDS AND GENTLE SEA CONDITIONS WILL THEN
CONTINUE THROUGH MONDAY. 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...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM UNTIL 9 PM

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: DYKEMA

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 182353
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
453 PM PDT SAT APR 18 2015

.SYNOPSIS...A MODERATELY DEEP MARINE LAYER ALONG THE COAST WILL
RESULT IN COOLER TEMPS ALONG THE COAST WHILE INLAND TEMPERATURES
REMAIN ABOVE AVERAGE. COOLER TEMPERATURES AND UNSETTLED WEATHER
ARE EXPECTED ACROSS THE DISTRICT THIS WEEK AS WEAK DISTURBANCES
SWING THROUGH THE REGION.

&&

.DISCUSSION...AS OF 2:35 PM PDT SATURDAY...WIDESPREAD STRATUS
ACROSS THE REGION CLEARED BACK TO THE COAST BY MID-MORNING TODAY
LEADING TO MAINLY CLEAR SKIES ACROSS MUCH OF THE DISTRICT WITH
EXCEPTION TO THE COAST AND COASTAL WATERS. TEMPERATURES THIS
AFTERNOON ARE RUNNING BETWEEN 5 TO 10 DEGREES COOLER THAN 24 HOURS
AGO WITH TEMPERATURES ALONG THE COAST SEEING THE GREATEST DROP.
CURRENT READINGS SHOW TEMPS IN THE 60S ALONG THE COAST WITH UPPER
60S AND 70S INLAND. NOT SURE TEMPERATURES WILL REACH THEIR
EXPECTED HIGHS TODAY WITH THE CLOUDY START WE HAD THIS MORNING.
THE SHORTENED ALLOWED HEATING TIME WILL DEFINITELY HAVE AN IMPACT
ON THE FINAL NUMBERS TODAY.

A WEAK SHORT WAVE APPROACHING THE DISTRICT FROM THE NORTH WILL
MAINTAIN A MODERATELY DEEP MARINE LAYER ALONG THE COAST. LOW
CLOUDS ARE EXPECTED TO PENETRATE WELL INLAND DURING THE NIGHT AND
MORNING HOURS AS A RESULT. AS THIS SHORT WAVE SLIDES SOUTH MODELS
SHOW A LOW CUTTING OFF OVER NORTHERN CALIFORNIA THIS AFTERNOON.
THE LOW THEN VEERS TO THE WEST AND MEANDERS SOUTHWARD THROUGH
SUNDAY. THIS SYSTEM WILL SERVE TO ENHANCE THE MARINE LAYER ALONG
THE COAST RESULTING COOLING ALONG THE COAST AS WELL AS AREAS
AFFECTED BY THE MARINE LAYER. OTHERWISE CONDITIONS ARE EXPECTED TO
REMAIN MILD AND DRY.

BY MONDAY AFTERNOON THE LOW IS FORECAST TO SWING INTO SOUTHERN
CALIFORNIA. MODELS CONTINUE TO SHOW INCREASED INSTABILITY OVER THE
GABILAN AND SANTA LUCIA RANGES AS WELL AS THE NORTHERNMOST
MOUNTAINS OVER NAPA AND SONOMA. HOWEVER THE MOISTURE IS NOT THERE
TO SUPPORT ANYTHING MORE THAN AN ISOLATED SPRINKLE OR
THUNDERSTORM.

THE CHANCE OF AN ISOLATED SHOWER OR THUNDERSTORM INCREASES TUESDAY
AFTERNOON WITH A SLIGHT INCREASE MOISTURE OVER THE REGION. HAVE
INTRODUCED A SLIGHT CHANCE OF THUNDERSTORMS TO THE NORTHERNMOST
PORTIONS OF NAPA AND SONOMA AS WELL AS THE EASTERN FLANK OF THE
CWA AND THE MOUNTAINS OF MONTEREY AND SAN BENITO COUNTIES.

TEMPERATURES ACROSS THE REGION WILL GRADUALLY COOL THROUGH THE
REMAINDER OF THE WEEK AS A BROAD LONG WAVE TROUGH SWEEPS THROUGH
THE REGION. A FEW WEAK IMPULSES ARE PROGGED TO ROTATE THROUGH THE
LONG WAVE TROUGH TUESDAY AND WEDNESDAY WHICH WILL BRING A SLIGHT
CHANCE OF ISOLATED SHOWERS TO THE REGION.

MODEL SOLUTIONS BEGIN TO DIVERGE TOWARD THE END OF THE WEEK.
HOWEVER IT APPEARS THE WEATHER PATTERN WILL REMAIN UNSETTLED.
THE ECMWF AND CANADIAN DEPICT A MODERATE COLD FRONT SLIDING
THROUGH THE REGION FRIDAY INTO SATURDAY. THIS SOLUTION WOULD
BRING WIDESPREAD RAIN TO THE DISTRICT. MADE LITTLE CHANGE TO THE
EXTENDED AND MAINTAINED AN UNSETTLED PATTERN AND SLIGHTLY BELOW
NORMAL TEMPS.

&&

.AVIATION...AS OF 4:50 PM PDT SATURDAY...MARINE LAYER WAS ABOUT
1000 FEET DEEP LATE SATURDAY AFTERNOON...BUT IS EXPECTED TO DEEPEN
SLIGHTLY OVERNIGHT AND INTO SUNDAY. ONSHORE GRADIENTS ARE SLIGHTLY
STRONGER THAN YESTERDAY. THESE FACTORS FAVOR EARLIER DEVELOPMENT
OF LOW CIGS AROUND SF BAY TONIGHT COMPARED TO LAST NIGHT AND THEN
LATER CLEARING ON SUNDAY. HOWEVER...EDDY CIRCULATION OFF GOLDEN
GATE MAY HELP DELAY DEVELOPMENT OF LOW CIGS IN SF BAY UNTIL LATE
EVENING OR AROUND MIDNIGHT. LIGHT TO MODERATE WESTERLY WINDS THIS
EVENING AND AGAIN BY LATE SUNDAY AFTERNOON.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH MOST OF THE
EVENING. CIGS LIKELY TO DEVELOP OVERNIGHT...BUT CONFIDENCE IS
LOW/MEDIUM ON TIMING. EDDY CIRCULATION OFFSHORE IS EXPECTED TO
DELAY IFR/MVFR CIG ONSET UNTIL 09-10Z. LOW CIGS EXPECTED TO CLEAR
AROUND 18Z SUNDAY MORNING. WEST WINDS 16G20 KT THIS
EVENING...GRADUALLY DECREASING OVERNIGHT.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS LIKELY TO DEVELOP BY 04-05Z
AND THEN PERSIST THROUGH 18Z SUNDAY. LIGHT WESTERLY WINDS EARLY THIS
EVENING BECOMING LIGHT AND VARIABLE BY MIDNIGHT.

&&

.MARINE...AS OF 2:34 PM PDT SATURDAY...NORTHWEST FLOW UNDER HIGH
PRESSURE OVER THE COASTAL WATERS TONIGHT. WINDS WILL BE STRONGEST
WELL OFFSHORE OF POINT ARENAS. ELSEWHERE WINDS WILL GENERALLY BE
LIGHT THROUGH MONDAY. SEA CONDITIONS GRADUALLY IMPROVE INTO
MONDAY. WINDS AND SEAS INCREASE TUESDAY THROUGH MID WEEK.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM UNTIL 9 PM

&&

$$

PUBLIC FORECAST: CW
AVIATION: DYKEMA
MARINE: DRP

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000
FXUS66 KMTR 182353
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
453 PM PDT SAT APR 18 2015

.SYNOPSIS...A MODERATELY DEEP MARINE LAYER ALONG THE COAST WILL
RESULT IN COOLER TEMPS ALONG THE COAST WHILE INLAND TEMPERATURES
REMAIN ABOVE AVERAGE. COOLER TEMPERATURES AND UNSETTLED WEATHER
ARE EXPECTED ACROSS THE DISTRICT THIS WEEK AS WEAK DISTURBANCES
SWING THROUGH THE REGION.

&&

.DISCUSSION...AS OF 2:35 PM PDT SATURDAY...WIDESPREAD STRATUS
ACROSS THE REGION CLEARED BACK TO THE COAST BY MID-MORNING TODAY
LEADING TO MAINLY CLEAR SKIES ACROSS MUCH OF THE DISTRICT WITH
EXCEPTION TO THE COAST AND COASTAL WATERS. TEMPERATURES THIS
AFTERNOON ARE RUNNING BETWEEN 5 TO 10 DEGREES COOLER THAN 24 HOURS
AGO WITH TEMPERATURES ALONG THE COAST SEEING THE GREATEST DROP.
CURRENT READINGS SHOW TEMPS IN THE 60S ALONG THE COAST WITH UPPER
60S AND 70S INLAND. NOT SURE TEMPERATURES WILL REACH THEIR
EXPECTED HIGHS TODAY WITH THE CLOUDY START WE HAD THIS MORNING.
THE SHORTENED ALLOWED HEATING TIME WILL DEFINITELY HAVE AN IMPACT
ON THE FINAL NUMBERS TODAY.

A WEAK SHORT WAVE APPROACHING THE DISTRICT FROM THE NORTH WILL
MAINTAIN A MODERATELY DEEP MARINE LAYER ALONG THE COAST. LOW
CLOUDS ARE EXPECTED TO PENETRATE WELL INLAND DURING THE NIGHT AND
MORNING HOURS AS A RESULT. AS THIS SHORT WAVE SLIDES SOUTH MODELS
SHOW A LOW CUTTING OFF OVER NORTHERN CALIFORNIA THIS AFTERNOON.
THE LOW THEN VEERS TO THE WEST AND MEANDERS SOUTHWARD THROUGH
SUNDAY. THIS SYSTEM WILL SERVE TO ENHANCE THE MARINE LAYER ALONG
THE COAST RESULTING COOLING ALONG THE COAST AS WELL AS AREAS
AFFECTED BY THE MARINE LAYER. OTHERWISE CONDITIONS ARE EXPECTED TO
REMAIN MILD AND DRY.

BY MONDAY AFTERNOON THE LOW IS FORECAST TO SWING INTO SOUTHERN
CALIFORNIA. MODELS CONTINUE TO SHOW INCREASED INSTABILITY OVER THE
GABILAN AND SANTA LUCIA RANGES AS WELL AS THE NORTHERNMOST
MOUNTAINS OVER NAPA AND SONOMA. HOWEVER THE MOISTURE IS NOT THERE
TO SUPPORT ANYTHING MORE THAN AN ISOLATED SPRINKLE OR
THUNDERSTORM.

THE CHANCE OF AN ISOLATED SHOWER OR THUNDERSTORM INCREASES TUESDAY
AFTERNOON WITH A SLIGHT INCREASE MOISTURE OVER THE REGION. HAVE
INTRODUCED A SLIGHT CHANCE OF THUNDERSTORMS TO THE NORTHERNMOST
PORTIONS OF NAPA AND SONOMA AS WELL AS THE EASTERN FLANK OF THE
CWA AND THE MOUNTAINS OF MONTEREY AND SAN BENITO COUNTIES.

TEMPERATURES ACROSS THE REGION WILL GRADUALLY COOL THROUGH THE
REMAINDER OF THE WEEK AS A BROAD LONG WAVE TROUGH SWEEPS THROUGH
THE REGION. A FEW WEAK IMPULSES ARE PROGGED TO ROTATE THROUGH THE
LONG WAVE TROUGH TUESDAY AND WEDNESDAY WHICH WILL BRING A SLIGHT
CHANCE OF ISOLATED SHOWERS TO THE REGION.

MODEL SOLUTIONS BEGIN TO DIVERGE TOWARD THE END OF THE WEEK.
HOWEVER IT APPEARS THE WEATHER PATTERN WILL REMAIN UNSETTLED.
THE ECMWF AND CANADIAN DEPICT A MODERATE COLD FRONT SLIDING
THROUGH THE REGION FRIDAY INTO SATURDAY. THIS SOLUTION WOULD
BRING WIDESPREAD RAIN TO THE DISTRICT. MADE LITTLE CHANGE TO THE
EXTENDED AND MAINTAINED AN UNSETTLED PATTERN AND SLIGHTLY BELOW
NORMAL TEMPS.

&&

.AVIATION...AS OF 4:50 PM PDT SATURDAY...MARINE LAYER WAS ABOUT
1000 FEET DEEP LATE SATURDAY AFTERNOON...BUT IS EXPECTED TO DEEPEN
SLIGHTLY OVERNIGHT AND INTO SUNDAY. ONSHORE GRADIENTS ARE SLIGHTLY
STRONGER THAN YESTERDAY. THESE FACTORS FAVOR EARLIER DEVELOPMENT
OF LOW CIGS AROUND SF BAY TONIGHT COMPARED TO LAST NIGHT AND THEN
LATER CLEARING ON SUNDAY. HOWEVER...EDDY CIRCULATION OFF GOLDEN
GATE MAY HELP DELAY DEVELOPMENT OF LOW CIGS IN SF BAY UNTIL LATE
EVENING OR AROUND MIDNIGHT. LIGHT TO MODERATE WESTERLY WINDS THIS
EVENING AND AGAIN BY LATE SUNDAY AFTERNOON.

VICINITY OF KSFO...VFR CONDITIONS EXPECTED THROUGH MOST OF THE
EVENING. CIGS LIKELY TO DEVELOP OVERNIGHT...BUT CONFIDENCE IS
LOW/MEDIUM ON TIMING. EDDY CIRCULATION OFFSHORE IS EXPECTED TO
DELAY IFR/MVFR CIG ONSET UNTIL 09-10Z. LOW CIGS EXPECTED TO CLEAR
AROUND 18Z SUNDAY MORNING. WEST WINDS 16G20 KT THIS
EVENING...GRADUALLY DECREASING OVERNIGHT.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS LIKELY TO DEVELOP BY 04-05Z
AND THEN PERSIST THROUGH 18Z SUNDAY. LIGHT WESTERLY WINDS EARLY THIS
EVENING BECOMING LIGHT AND VARIABLE BY MIDNIGHT.

&&

.MARINE...AS OF 2:34 PM PDT SATURDAY...NORTHWEST FLOW UNDER HIGH
PRESSURE OVER THE COASTAL WATERS TONIGHT. WINDS WILL BE STRONGEST
WELL OFFSHORE OF POINT ARENAS. ELSEWHERE WINDS WILL GENERALLY BE
LIGHT THROUGH MONDAY. SEA CONDITIONS GRADUALLY IMPROVE INTO
MONDAY. WINDS AND SEAS INCREASE TUESDAY THROUGH MID WEEK.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM UNTIL 9 PM

&&

$$

PUBLIC FORECAST: CW
AVIATION: DYKEMA
MARINE: DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 182136
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
236 PM PDT SAT APR 18 2015

.SYNOPSIS...A MODERATELY DEEP MARINE LAYER ALONG THE COAST WILL
RESULT IN COOLER TEMPS ALONG THE COAST WHILE INLAND TEMPERATURES
REMAIN ABOVE AVERAGE. COOLER TEMPERATURES AND UNSETTLED WEATHER
ARE EXPECTED ACROSS THE DISTRICT THIS WEEK AS WEAK DISTURBANCES
SWING THROUGH THE REGION.

&&

.DISCUSSION...AS OF 2:35 PM PDT SATURDAY...WIDESPREAD STRATUS
ACROSS THE REGION CLEARED BACK TO THE COAST BY MID-MORNING TODAY
LEADING TO MAINLY CLEAR SKIES ACROSS MUCH OF THE DISTRICT WITH
EXCEPTION TO THE COAST AND COASTAL WATERS. TEMPERATURES THIS
AFTERNOON ARE RUNNING BETWEEN 5 TO 10 DEGREES COOLER THAN 24 HOURS
AGO WITH TEMPERATURES ALONG THE COAST SEEING THE GREATEST DROP.
CURRENT READINGS SHOW TEMPS IN THE 60S ALONG THE COAST WITH UPPER
60S AND 70S INLAND. NOT SURE TEMPERATURES WILL REACH THEIR
EXPECTED HIGHS TODAY WITH THE CLOUDY START WE HAD THIS MORNING.
THE SHORTENED ALLOWED HEATING TIME WILL DEFINITELY HAVE AN IMPACT
ON THE FINAL NUMBERS TODAY.

A WEAK SHORT WAVE APPROACHING THE DISTRICT FROM THE NORTH WILL
MAINTAIN A MODERATELY DEEP MARINE LAYER ALONG THE COAST. LOW
CLOUDS ARE EXPECTED TO PENETRATE WELL INLAND DURING THE NIGHT AND
MORNING HOURS AS A RESULT. AS THIS SHORT WAVE SLIDES SOUTH MODELS
SHOW A LOW CUTTING OFF OVER NORTHERN CALIFORNIA THIS AFTERNOON.
THE LOW THEN VEERS TO THE WEST AND MEANDERS SOUTHWARD THROUGH
SUNDAY. THIS SYSTEM WILL SERVE TO ENHANCE THE MARINE LAYER ALONG
THE COAST RESULTING COOLING ALONG THE COAST AS WELL AS AREAS
AFFECTED BY THE MARINE LAYER. OTHERWISE CONDITIONS ARE EXPECTED TO
REMAIN MILD AND DRY.

BY MONDAY AFTERNOON THE LOW IS FORECAST TO SWING INTO SOUTHERN
CALIFORNIA. MODELS CONTINUE TO SHOW INCREASED INSTABILITY OVER THE
GABILAN AND SANTA LUCIA RANGES AS WELL AS THE NORTHERNMOST
MOUNTAINS OVER NAPA AND SONOMA. HOWEVER THE MOISTURE IS NOT THERE
TO SUPPORT ANYTHING MORE THAN AN ISOLATED SPRINKLE OR
THUNDERSTORM.

THE CHANCE OF AN ISOLATED SHOWER OR THUNDERSTORM INCREASES TUESDAY
AFTERNOON WITH A SLIGHT INCREASE MOISTURE OVER THE REGION. HAVE
INTRODUCED A SLIGHT CHANCE OF THUNDERSTORMS TO THE NORTHERNMOST
PORTIONS OF NAPA AND SONOMA AS WELL AS THE EASTERN FLANK OF THE
CWA AND THE MOUNTAINS OF MONTEREY AND SAN BENITO COUNTIES.

TEMPERATURES ACROSS THE REGION WILL GRADUALLY COOL THROUGH THE
REMAINDER OF THE WEEK AS A BROAD LONG WAVE TROUGH SWEEPS THROUGH
THE REGION. A FEW WEAK IMPULSES ARE PROGGED TO ROTATE THROUGH THE
LONG WAVE TROUGH TUESDAY AND WEDNESDAY WHICH WILL BRING A SLIGHT
CHANCE OF ISOLATED SHOWERS TO THE REGION.

MODEL SOLUTIONS BEGIN TO DIVERGE TOWARD THE END OF THE WEEK.
HOWEVER IT APPEARS THE WEATHER PATTERN WILL REMAIN UNSETTLED.
THE ECMWF AND CANADIAN DEPICT A MODERATE COLD FRONT SLIDING
THROUGH THE REGION FRIDAY INTO SATURDAY. THIS SOLUTION WOULD
BRING WIDESPREAD RAIN TO THE DISTRICT. MADE LITTLE CHANGE TO THE
EXTENDED AND MAINTAINED AN UNSETTLED PATTERN AND SLIGHTLY BELOW
NORMAL TEMPS.

&&

.AVIATION...AS OF 10:45 AM PDT SATURDAY... MARINE STRATUS
HAS RETREATED RATHER RAPIDLY AFTER AN OVERNIGHT PUSH INLAND. VFR
CONDITIONS ARE EXPECTED THROUGH THE REMAINDER OF THE DAYLIGHT
HOURS TODAY WITH PREDOMINATELY LIGHT WINDS. ONSHORE FLOW WILL
INCREASE THIS AFTERNOON WITH POSSIBLE GUSTS 20 KT OR LESS. WRF MODEL
STRUGGLING WITH THE LATEST MARINE STRATUS SCENARIO... SO LEANING
CLOSER TOWARDS NAM FOR GUIDANCE TONIGHT DESPITE NAM OVERESTIMATING
STRATUS FOR THE LAST SEVERAL MONTHS. MVFR/IFR CIGS FROM MARINE
STRATUS EXPECTED BETWEEN 03-10Z TONIGHT DEPENDING ON LOCATION.

VICINITY OF KSFO... VFR THRU DAYLIGHT HOURS. ONSHORE FLOW THIS
AFTERNOON WITH GUSTS UP TO 20 KT. IFR/STRATUS RETURNS TONIGHT BTWN
04-08Z.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS... VFR THRU DAYLIGHT HOURS. WEAK TO
MODERATE ONSHORE FLOW THIS AFTERNOON. IFR/STRATUS RETURNS TONIGHT
BETWEEN 03-06Z.

&&

.MARINE...AS OF 10:36 AM PDT SATURDAY...HIGH PRESSURE PRESENT OVER
THE COASTAL WATERS WILL RESULT IN NORTHWEST WINDS TODAY. WINDS
DECREASE THROUGH THE DAY AND WILL REMAIN LIGHT TO MODERATE INTO
EARLY NEXT WEEK. SEA CONDITIONS GRADUALLY IMPROVE INTO MONDAY
BEFORE DETERIORATING ON TUESDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM UNTIL 9 PM

&&

$$

PUBLIC FORECAST: CW
AVIATION/MARINE: DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 181743
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1043 AM PDT SAT APR 18 2015

.SYNOPSIS...HIGH PRESSURE ACROSS MUCH OF THE WEST COAST WILL
MAINTAIN ABOVE AVERAGE INLAND TEMPERATURES WITH COOLER CONDITIONS
NEAR THE COAST. CONDITIONS COOL REGION-WIDE EARLY IN THE WEEK WITH
UNSETTLED WEATHER POSSIBLE MID/LATE WEEK AS UPPER LEVEL TROUGHING
DEVELOPS OFF OF THE WEST COAST.

&&

.DISCUSSION...AS OF 9:00 AM PDT SATURDAY...WIDESPREAD STRATUS
PREVAILS ACROSS THE REGION THIS MORNING. THE FORT ORD PROFILER
SHOWS THE MARINE LAYER DEEPENED TO AROUND 1400 FEET THIS MORNING
IN RESPONSE TO A WEAK SHORT WAVE THAT IS APPROACHING FROM THE
NORTH. LATEST SATELLITE IMAGERY REVEALS STRATUS IS BEGINNING TO
ERODE OVER THE SALINAS AND SANTA CLARA VALLEYS. LOW CLOUDS ARE
ANTICIPATED TO RAPIDLY CLEAR OVER THE NEXT COUPLE OF HOURS MAKING
WAY FOR A BEAUTIFUL DAY. THE SHORT WAVE MENTIONED ABOVE IS
FORECAST TO SLIDE SOUTH WITH VERY LITTLE IMPACT TO OUR AREA OTHER
THAN AN EXPANDING MARINE LAYER AND ASSOCIATED COOLING ALONG THE
COAST. INLAND TEMPERATURES ARE NOT EXPECTED TO ONCE AGAIN CLIMB
INTO TO THE UPPER 70S AND 80S THIS AFTERNOON.

AS THE WEEKEND PROGRESSES THE WEAK SHORT WAVE IS PROGGED TO VEER
OFFSHORE AND CUT OFF TO THE WEST OF OUR AREA. AGAIN OTHER THAN AN
ENHANCED MARINE LAYER CONDITIONS WILL REMAIN WARM AND DRY WITH
COOLER CONDITIONS ALONG THE COAST.

THIS SYSTEM WILL SLIDE SOUTH OFF THE CENTRAL CALIFORNIA COAST ON
MONDAY. MODELS INDICATE THERE IS THE POTENTIAL FOR AN ISOLATED
SHOWER OR THUNDERSTORM OVER THE GABILAN AND SANTA LUCIA RANGES
MONDAY AFTERNOON DUE TO INCREASED INSTABILITY AND A SLIGHT
INCREASE IN MID-LEVEL MOISTURE OVER THE SOUTHERN HALF OF THE
REGION.

COOLER TEMPERATURES ARE IN STORE ACROSS THE REGION THROUGH THE
REMAINDER OF THE WEEK AS A BROAD LONG WAVE TROUGH SWEEPS THROUGH
THE REGION. ANOTHER CUT OFF LOW IS FORECAST TO DEVELOP OFF THE
NORTHERN CALIFORNIA COAST TUESDAY NIGHT INTO WEDNESDAY AND FOLLOW
A SIMILAR TRAJECTORY AS ITS PREDECESSOR. THIS LOW WILL BRING AND
SLIGHT CHANCE OF ISOLATED SHOWERS ACROSS THE REGION.

FROM PREVIOUS DISCUSSION... THE MEDIUM RANGE MODELS KEEP AN
UNSETTLED PATTERN OVER MUCH OF THE WEST COAST THROUGH THE
REMAINDER OF THE WEEK. THE ECMWF AND CMC BOTH SHOW A SOMEWHAT
STRONGER SYSTEM DROPPING SOUTHWARD ALONG THE COAST FRIDAY INTO
SATURDAY THAT WOULD BRING MORE WIDESPREAD RAINFALL TO THE REGION.
HOWEVER...THERE REMAINS A GREAT DEAL OF UNCERTAINTY IN THE RUN-TO-
RUN AND MODEL-TO-MODEL SOLUTIONS THIS FAR OUT. WITH ALL THAT
SAID...WILL KEEP TEMPERATURES NEAR OR SLIGHTLY BELOW SEASONAL
AVERAGES LATE IN THE FORECAST PERIOD ALONG WITH A SLIGHT CHANCE OF
PRECIPITATION.

&&

.AVIATION...AS OF 10:45 AM PDT SATURDAY... MARINE STRATUS
HAS RETREATED RATHER RAPIDLY AFTER AN OVERNIGHT PUSH INLAND. VFR
CONDITIONS ARE EXPECTED THROUGH THE REMAINDER OF THE DAYLIGHT
HOURS TODAY WITH PREDOMINATELY LIGHT WINDS. ONSHORE FLOW WILL
INCREASE THIS AFTERNOON WITH POSSIBLE GUSTS 20 KT OR LESS. WRF MODEL
STRUGGLING WITH THE LATEST MARINE STRATUS SCENARIO... SO LEANING
CLOSER TOWARDS NAM FOR GUIDANCE TONIGHT DESPITE NAM OVERESTIMATING
STRATUS FOR THE LAST SEVERAL MONTHS. MVFR/IFR CIGS FROM MARINE
STRATUS EXPECTED BETWEEN 03-10Z TONIGHT DEPENDING ON LOCATION.

VICINITY OF KSFO... VFR THRU DAYLIGHT HOURS. ONSHORE FLOW THIS
AFTERNOON WITH GUSTS UP TO 20 KT. IFR/STRATUS RETURNS TONIGHT BTWN
04-08Z.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS... VFR THRU DAYLIGHT HOURS. WEAK TO
MODERATE ONSHORE FLOW THIS AFTERNOON. IFR/STRATUS RETURNS TONIGHT
BETWEEN 03-06Z.

&&

.MARINE...AS OF 10:36 AM PDT SATURDAY...HIGH PRESSURE PRESENT OVER
THE COASTAL WATERS WILL RESULT IN NORTHWEST WINDS TODAY. WINDS
DECREASE THROUGH THE DAY AND WILL REMAIN LIGHT TO MODERATE INTO
EARLY NEXT WEEK. SEA CONDITIONS GRADUALLY IMPROVE INTO MONDAY
BEFORE DETERIORATING ON TUESDAY.

&&

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

&&

$$

PUBLIC FORECAST: CW
AVIATION/MARINE: DRP

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 181602
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
902 AM PDT SAT APR 18 2015

.SYNOPSIS...HIGH PRESSURE ACROSS MUCH OF THE WEST COAST WILL
MAINTAIN ABOVE AVERAGE INLAND TEMPERATURES WITH COOLER CONDITIONS
NEAR THE COAST. CONDITIONS COOL REGION-WIDE EARLY IN THE WEEK WITH
UNSETTLED WEATHER POSSIBLE MID/LATE WEEK AS UPPER LEVEL TROUGHING
DEVELOPS OFF OF THE WEST COAST.

&&

.DISCUSSION...AS OF 9:00 AM PDT SATURDAY...WIDESPREAD STRATUS
PREVAILS ACROSS THE REGION THIS MORNING. THE FORT ORD PROFILER
SHOWS THE MARINE LAYER DEEPENED TO AROUND 1400 FEET THIS MORNING
IN RESPONSE TO A WEAK SHORT WAVE THAT IS APPROACHING FROM THE
NORTH. LATEST SATELLITE IMAGERY REVEALS STRATUS IS BEGINNING TO
ERODE OVER THE SALINAS AND SANTA CLARA VALLEYS. LOW CLOUDS ARE
ANTICIPATED TO RAPIDLY CLEAR OVER THE NEXT COUPLE OF HOURS MAKING
WAY FOR A BEAUTIFUL DAY. THE SHORT WAVE MENTIONED ABOVE IS
FORECAST TO SLIDE SOUTH WITH VERY LITTLE IMPACT TO OUR AREA OTHER
THAN AN EXPANDING MARINE LAYER AND ASSOCIATED COOLING ALONG THE
COAST. INLAND TEMPERATURES ARE NOT EXPECTED TO ONCE AGAIN CLIMB
INTO TO THE UPPER 70S AND 80S THIS AFTERNOON.

AS THE WEEKEND PROGRESSES THE WEAK SHORT WAVE IS PROGGED TO VEER
OFFSHORE AND CUT OFF TO THE WEST OF OUR AREA. AGAIN OTHER THAN AN
ENHANCED MARINE LAYER CONDITIONS WILL REMAIN WARM AND DRY WITH
COOLER CONDITIONS ALONG THE COAST.

THIS SYSTEM WILL SLIDE SOUTH OFF THE CENTRAL CALIFORNIA COAST ON
MONDAY. MODELS INDICATE THERE IS THE POTENTIAL FOR AN ISOLATED
SHOWER OR THUNDERSTORM OVER THE GABILAN AND SANTA LUCIA RANGES
MONDAY AFTERNOON DUE TO INCREASED INSTABILITY AND A SLIGHT
INCREASE IN MID-LEVEL MOISTURE OVER THE SOUTHERN HALF OF THE
REGION.

COOLER TEMPERATURES ARE IN STORE ACROSS THE REGION THROUGH THE
REMAINDER OF THE WEEK AS A BROAD LONG WAVE TROUGH SWEEPS THROUGH
THE REGION. ANOTHER CUT OFF LOW IS FORECAST TO DEVELOP OFF THE
NORTHERN CALIFORNIA COAST TUESDAY NIGHT INTO WEDNESDAY AND FOLLOW
A SIMILAR TRAJECTORY AS ITS PREDECESSOR. THIS LOW WILL BRING AND
SLIGHT CHANCE OF ISOLATED SHOWERS ACROSS THE REGION.

FROM PREVIOUS DISCUSSION... THE MEDIUM RANGE MODELS KEEP AN
UNSETTLED PATTERN OVER MUCH OF THE WEST COAST THROUGH THE
REMAINDER OF THE WEEK. THE ECMWF AND CMC BOTH SHOW A SOMEWHAT
STRONGER SYSTEM DROPPING SOUTHWARD ALONG THE COAST FRIDAY INTO
SATURDAY THAT WOULD BRING MORE WIDESPREAD RAINFALL TO THE REGION.
HOWEVER...THERE REMAINS A GREAT DEAL OF UNCERTAINTY IN THE RUN-TO-
RUN AND MODEL-TO-MODEL SOLUTIONS THIS FAR OUT. WITH ALL THAT
SAID...WILL KEEP TEMPERATURES NEAR OR SLIGHTLY BELOW SEASONAL
AVERAGES LATE IN THE FORECAST PERIOD ALONG WITH A SLIGHT CHANCE OF
PRECIPITATION.

&&

.AVIATION...AS OF 4:39 AM PDT SATURDAY...STRATUS AND FOG COVERAGE
IS MORE EXTENSIVE THAN THE WRF MODEL GUIDANCE SHOWS EARLY THIS
MORNING. INCREASES IN SURFACE HUMIDITY OVERNIGHT ON TOP OF CHILLY
SEA SURFACE TEMPS IS RESULTING IN A FAIRLY LARGE AREA OF
STRATUS/FOG FROM POINT ARENA SOUTH TO POINT CONCEPTION. AREA
PROFILER DATA INDICATING THE MARINE LAYER DEPTH IS NEAR 1000 FEET.
THE SFO-SAC PRESS GRADIENT IS 2 MB WHILE THE ACV-SFO IS 2.4. THE
ACV-SFO IS FORECASTED TO WEAKEN TODAY WHILE THE SFO-SAC GRADIENT
REACHES 3 MB BY MID-LATE AFTERNOON FURTHER STRENGTHENING THE
ONSHORE WINDS. THE LOW LEVEL TEMPS WILL INCREASE BY 1 DEG C
THROUGH TODAY AS WELL WHICH WILL CONTINUE TO SUPPORT THE MARINE
LAYER INVERSION.

VICINITY OF KSFO...THE SATELLITE STRATUS/FOG PRODUCT SHOWS A CLEAR
SKY...BUT LOW CLOUD PATCHES ARE NOT VERY FAR AWAY FROM THE SFO
APPROACH. IT`S A DIFFICULT FORECAST THIS MORNING...NOT SO MUCH
THAT THE MARINE LAYER INVERSION AT 1000 FEET AND LIGHT WESTERLY
SURFACE WIND DO NOT SUPPORT STRATUS AND/OR FOG ADVECTION THROUGH
THE SAN BRUNO GAP...BUT WILL NEED TO WATCH THOSE PATCHY LOW CLOUDS
THAT ARE SLOWLY APPROACHING THE TERMINAL AND APPROACH FROM THE
SE-E. SO FAR KSFO AND SAN MATEO BRIDGE ARE REPORTING CLEAR. THE
SLUGGISH MOVEMENT OF STRATUS/FOG OVER SF BAY WITHIN A LIGHT WIND
ENVIRONMENT SUPPORTS TEMPO IFR CIG 12Z-16Z. OTHERWISE VFR TODAY.
SINCE THE WRF MODEL IS UNDER-FORECASTING STRATUS/FOG AM NOT VERY
CERTAIN HOW MUCH CLEARING THERE`LL ON THE OCEAN SIDE OF THE SF
PENINSULA TODAY EXCEPT THAT A HIGHER APRIL SUN ANGLE IS OFTEN
HELPFUL WITH AIR MASS MIXING AND CLEARING. STRATUS RETURNING TONIGHT?
PROBABLY...GIVEN ONSHORE WINDS AND A WEAKENED UPPER LEVEL HIGH BUT
VERY LOW CONFIDENCE TO TRY TO TIME IN THE 12Z TAF.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS CLEARING BY 17Z-18Z THIS
MORNING. LOW CONFIDENCE.

&&

.MARINE...AS OF 4:11 AM PDT SATURDAY...MAINLY LIGHT NORTHWESTERLY
WINDS WILL CONTINUE THROUGH THE BEGINNING OF THE WORK WEEK. NORTHERLY
WINDS WILL INCREASE ONCE AGAIN ACROSS THE COASTAL WATERS BY THE
MIDDLE OF NEXT WEEK. SEAS ARE EXPECTED TO DECREASE AS GENTLER SEAS
MOVE IN FOR THE REMAINDER OF THE WEEKEND.

&&

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

&&

$$

PUBLIC FORECAST: CW
AVIATION/MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 181154
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
454 AM PDT SAT APR 18 2015

.SYNOPSIS...HIGH PRESSURE ACROSS MUCH OF THE WEST COAST WILL
MAINTAIN ABOVE AVERAGE INLAND TEMPERATURES WITH COOLER CONDITIONS
NEAR THE COAST. CONDITIONS COOL REGION-WIDE EARLY IN THE WEEK WITH
UNSETTLED WEATHER POSSIBLE MID/LATE WEEK AS UPPER LEVEL TROUGHING
DEVELOPS OFF OF THE WEST COAST.

&&

.DISCUSSION...AS OF 04:11 AM PDT SATURDAY...A WEAK MID/UPPER
LEVEL SHORT-WAVE TROUGH APPROACHING THE REGION FROM THE NORTH HAS
HELPED ENHANCE THE MARINE LAYER EARLY THIS MORNING...NOW AROUND
1000 FT. THIS RESULTED IN AN INCREASE IN LOW LEVEL CLOUDS ALONG
THE COAST AND SUPPORTED INLAND PENETRATION INTO THE SALINAS AND
NORTH BAY VALLEYS OVERNIGHT. WHILE THE INCREASED PRESENCE OF THE
MARINE LAYER IS EXPECTED TO KEEP CONDITIONS COOL ALONG THE COAST
TODAY...THE WEAK MID/UPPER LEVEL FEATURE WILL DO LITTLE TO COOL
850MB TEMPERATURES. THUS...INLAND LOCATIONS WILL ONCE AGAIN WARM
INTO THE UPPER 70S TO 80S THIS AFTERNOON. BY SUNDAY...THE WEAK
SHORT-WAVE SYSTEM IS FORECAST TO DEVELOP INTO A CLOSED LOW OFF OF
THE NORTHERN CALIFORNIA COAST. WHILE THIS WILL HELP FURTHER
ENHANCE THE MARINE LAYER THROUGH THE WEEKEND...DRY CONDITIONS AND
WARM INLAND TEMPERATURES ARE EXPECTED TO PERSIST WITH LIMITED
MOISTURE ALOFT.

THE WEAK CUT-OFF LOW PRESSURE SYSTEM WILL LINGER OFF OF THE
CALIFORNIA COAST HEADING INTO EARLY NEXT WEEK WITH AN INCREASE IN
ONSHORE FLOW. THE FORECAST MODELS ALSO INDICATE A SLIGHT INCREASE
IN MID-LEVEL MOISTURE AND INSTABILITY OVER THE SOUTHERN HALF OF
THE REGION ON MONDAY...RESULTING IN THE POTENTIAL FOR AN ISOLATED
SHOWER OR THUNDERSTORM OVER THE HIGHER HILLS SOUTHERN MONTEREY
AND SAN BENITO COUNTIES. OTHERWISE...TEMPERATURES WILL BEGIN TO
COOL REGION-WIDE AHEAD OF A MORE BROAD MID/UPPER LEVEL TROUGH
FORECAST TO APPROACH THE REGION TUESDAY. THE FORECAST MODELS THEN
DEVELOP ANOTHER CLOSED LOW OFF OF THE CALIFORNIA COAST THAT WILL
SLIDE DOWN THE COAST THROUGH MIDWEEK...RESULTING A SLIGHT CHANCE
OF SHOWERS ACROSS THE REGION. HOWEVER...MOISTURE WILL ONCE AGAIN
BE LIMITED AND THE MEDIUM RANGE MODELS KEEP THE BEST CHANCES OF
PRECIPITATION OVER THE HIGHER TERRAIN/MORE INLAND AREAS OF THE
STATE. THUS...NOT EXPECTING ANY ORGANIZED/WIDESPREAD
PRECIPITATION OVER THE REGION AT THIS TIME.

THE MEDIUM RANGE MODELS KEEP AN UNSETTLED PATTERN OVER MUCH OF
THE WEST COAST THROUGH THE REMAINDER OF THE WEEK. THE ECMWF AND
CMC BOTH SHOW A SOMEWHAT STRONGER SYSTEM DROPPING SOUTHWARD ALONG
THE COAST FRIDAY INTO SATURDAY THAT WOULD BRING MORE WIDESPREAD
RAINFALL TO THE REGION. HOWEVER...THERE REMAINS A GREAT DEAL OF
UNCERTAINTY IN THE RUN-TO-RUN AND MODEL-TO-MODEL SOLUTIONS THIS
FAR OUT. WITH ALL THAT SAID...WILL KEEP TEMPERATURES NEAR OR
SLIGHTLY BELOW SEASONAL AVERAGES LATE IN THE FORECAST PERIOD
ALONG WITH A SLIGHT CHANCE OF PRECIPITATION.

&&

.AVIATION...AS OF 4:39 AM PDT SATURDAY...STRATUS AND FOG COVERAGE
IS MORE EXTENSIVE THAN THE WRF MODEL GUIDANCE SHOWS EARLY THIS
MORNING. INCREASES IN SURFACE HUMIDITY OVERNIGHT ON TOP OF CHILLY
SEA SURFACE TEMPS IS RESULTING IN A FAIRLY LARGE AREA OF
STRATUS/FOG FROM POINT ARENA SOUTH TO POINT CONCEPTION. AREA
PROFILER DATA INDICATING THE MARINE LAYER DEPTH IS NEAR 1000 FEET.
THE SFO-SAC PRESS GRADIENT IS 2 MB WHILE THE ACV-SFO IS 2.4. THE
ACV-SFO IS FORECASTED TO WEAKEN TODAY WHILE THE SFO-SAC GRADIENT
REACHES 3 MB BY MID-LATE AFTERNOON FURTHER STRENGTHENING THE
ONSHORE WINDS. THE LOW LEVEL TEMPS WILL INCREASE BY 1 DEG C
THROUGH TODAY AS WELL WHICH WILL CONTINUE TO SUPPORT THE MARINE
LAYER INVERSION.

VICINITY OF KSFO...THE SATELLITE STRATUS/FOG PRODUCT SHOWS A CLEAR
SKY...BUT LOW CLOUD PATCHES ARE NOT VERY FAR AWAY FROM THE SFO
APPROACH. IT`S A DIFFICULT FORECAST THIS MORNING...NOT SO MUCH
THAT THE MARINE LAYER INVERSION AT 1000 FEET AND LIGHT WESTERLY
SURFACE WIND DO NOT SUPPORT STRATUS AND/OR FOG ADVECTION THROUGH
THE SAN BRUNO GAP...BUT WILL NEED TO WATCH THOSE PATCHY LOW CLOUDS
THAT ARE SLOWLY APPROACHING THE TERMINAL AND APPROACH FROM THE
SE-E. SO FAR KSFO AND SAN MATEO BRIDGE ARE REPORTING CLEAR. THE
SLUGGISH MOVEMENT OF STRATUS/FOG OVER SF BAY WITHIN A LIGHT WIND
ENVIRONMENT SUPPORTS TEMPO IFR CIG 12Z-16Z. OTHERWISE VFR TODAY.
SINCE THE WRF MODEL IS UNDER-FORECASTING STRATUS/FOG AM NOT VERY
CERTAIN HOW MUCH CLEARING THERE`LL ON THE OCEAN SIDE OF THE SF
PENINSULA TODAY EXCEPT THAT A HIGHER APRIL SUN ANGLE IS OFTEN
HELPFUL WITH AIR MASS MIXING AND CLEARING. STRATUS RETURNING TONIGHT?
PROBABLY...GIVEN ONSHORE WINDS AND A WEAKENED UPPER LEVEL HIGH BUT
VERY LOW CONFIDENCE TO TRY TO TIME IN THE 12Z TAF.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS CLEARING BY 17Z-18Z THIS
MORNING. LOW CONFIDENCE.

&&

.MARINE...AS OF 4:11 AM PDT SATURDAY...MAINLY LIGHT NORTHWESTERLY
WINDS WILL CONTINUE THROUGH THE BEGINNING OF THE WORK WEEK. NORTHERLY
WINDS WILL INCREASE ONCE AGAIN ACROSS THE COASTAL WATERS BY THE
MIDDLE OF NEXT WEEK. SEAS ARE EXPECTED TO DECREASE AS GENTLER SEAS
MOVE IN FOR THE REMAINDER OF THE WEEKEND.

&&

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

&&

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA









000
FXUS66 KMTR 181154
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
454 AM PDT SAT APR 18 2015

.SYNOPSIS...HIGH PRESSURE ACROSS MUCH OF THE WEST COAST WILL
MAINTAIN ABOVE AVERAGE INLAND TEMPERATURES WITH COOLER CONDITIONS
NEAR THE COAST. CONDITIONS COOL REGION-WIDE EARLY IN THE WEEK WITH
UNSETTLED WEATHER POSSIBLE MID/LATE WEEK AS UPPER LEVEL TROUGHING
DEVELOPS OFF OF THE WEST COAST.

&&

.DISCUSSION...AS OF 04:11 AM PDT SATURDAY...A WEAK MID/UPPER
LEVEL SHORT-WAVE TROUGH APPROACHING THE REGION FROM THE NORTH HAS
HELPED ENHANCE THE MARINE LAYER EARLY THIS MORNING...NOW AROUND
1000 FT. THIS RESULTED IN AN INCREASE IN LOW LEVEL CLOUDS ALONG
THE COAST AND SUPPORTED INLAND PENETRATION INTO THE SALINAS AND
NORTH BAY VALLEYS OVERNIGHT. WHILE THE INCREASED PRESENCE OF THE
MARINE LAYER IS EXPECTED TO KEEP CONDITIONS COOL ALONG THE COAST
TODAY...THE WEAK MID/UPPER LEVEL FEATURE WILL DO LITTLE TO COOL
850MB TEMPERATURES. THUS...INLAND LOCATIONS WILL ONCE AGAIN WARM
INTO THE UPPER 70S TO 80S THIS AFTERNOON. BY SUNDAY...THE WEAK
SHORT-WAVE SYSTEM IS FORECAST TO DEVELOP INTO A CLOSED LOW OFF OF
THE NORTHERN CALIFORNIA COAST. WHILE THIS WILL HELP FURTHER
ENHANCE THE MARINE LAYER THROUGH THE WEEKEND...DRY CONDITIONS AND
WARM INLAND TEMPERATURES ARE EXPECTED TO PERSIST WITH LIMITED
MOISTURE ALOFT.

THE WEAK CUT-OFF LOW PRESSURE SYSTEM WILL LINGER OFF OF THE
CALIFORNIA COAST HEADING INTO EARLY NEXT WEEK WITH AN INCREASE IN
ONSHORE FLOW. THE FORECAST MODELS ALSO INDICATE A SLIGHT INCREASE
IN MID-LEVEL MOISTURE AND INSTABILITY OVER THE SOUTHERN HALF OF
THE REGION ON MONDAY...RESULTING IN THE POTENTIAL FOR AN ISOLATED
SHOWER OR THUNDERSTORM OVER THE HIGHER HILLS SOUTHERN MONTEREY
AND SAN BENITO COUNTIES. OTHERWISE...TEMPERATURES WILL BEGIN TO
COOL REGION-WIDE AHEAD OF A MORE BROAD MID/UPPER LEVEL TROUGH
FORECAST TO APPROACH THE REGION TUESDAY. THE FORECAST MODELS THEN
DEVELOP ANOTHER CLOSED LOW OFF OF THE CALIFORNIA COAST THAT WILL
SLIDE DOWN THE COAST THROUGH MIDWEEK...RESULTING A SLIGHT CHANCE
OF SHOWERS ACROSS THE REGION. HOWEVER...MOISTURE WILL ONCE AGAIN
BE LIMITED AND THE MEDIUM RANGE MODELS KEEP THE BEST CHANCES OF
PRECIPITATION OVER THE HIGHER TERRAIN/MORE INLAND AREAS OF THE
STATE. THUS...NOT EXPECTING ANY ORGANIZED/WIDESPREAD
PRECIPITATION OVER THE REGION AT THIS TIME.

THE MEDIUM RANGE MODELS KEEP AN UNSETTLED PATTERN OVER MUCH OF
THE WEST COAST THROUGH THE REMAINDER OF THE WEEK. THE ECMWF AND
CMC BOTH SHOW A SOMEWHAT STRONGER SYSTEM DROPPING SOUTHWARD ALONG
THE COAST FRIDAY INTO SATURDAY THAT WOULD BRING MORE WIDESPREAD
RAINFALL TO THE REGION. HOWEVER...THERE REMAINS A GREAT DEAL OF
UNCERTAINTY IN THE RUN-TO-RUN AND MODEL-TO-MODEL SOLUTIONS THIS
FAR OUT. WITH ALL THAT SAID...WILL KEEP TEMPERATURES NEAR OR
SLIGHTLY BELOW SEASONAL AVERAGES LATE IN THE FORECAST PERIOD
ALONG WITH A SLIGHT CHANCE OF PRECIPITATION.

&&

.AVIATION...AS OF 4:39 AM PDT SATURDAY...STRATUS AND FOG COVERAGE
IS MORE EXTENSIVE THAN THE WRF MODEL GUIDANCE SHOWS EARLY THIS
MORNING. INCREASES IN SURFACE HUMIDITY OVERNIGHT ON TOP OF CHILLY
SEA SURFACE TEMPS IS RESULTING IN A FAIRLY LARGE AREA OF
STRATUS/FOG FROM POINT ARENA SOUTH TO POINT CONCEPTION. AREA
PROFILER DATA INDICATING THE MARINE LAYER DEPTH IS NEAR 1000 FEET.
THE SFO-SAC PRESS GRADIENT IS 2 MB WHILE THE ACV-SFO IS 2.4. THE
ACV-SFO IS FORECASTED TO WEAKEN TODAY WHILE THE SFO-SAC GRADIENT
REACHES 3 MB BY MID-LATE AFTERNOON FURTHER STRENGTHENING THE
ONSHORE WINDS. THE LOW LEVEL TEMPS WILL INCREASE BY 1 DEG C
THROUGH TODAY AS WELL WHICH WILL CONTINUE TO SUPPORT THE MARINE
LAYER INVERSION.

VICINITY OF KSFO...THE SATELLITE STRATUS/FOG PRODUCT SHOWS A CLEAR
SKY...BUT LOW CLOUD PATCHES ARE NOT VERY FAR AWAY FROM THE SFO
APPROACH. IT`S A DIFFICULT FORECAST THIS MORNING...NOT SO MUCH
THAT THE MARINE LAYER INVERSION AT 1000 FEET AND LIGHT WESTERLY
SURFACE WIND DO NOT SUPPORT STRATUS AND/OR FOG ADVECTION THROUGH
THE SAN BRUNO GAP...BUT WILL NEED TO WATCH THOSE PATCHY LOW CLOUDS
THAT ARE SLOWLY APPROACHING THE TERMINAL AND APPROACH FROM THE
SE-E. SO FAR KSFO AND SAN MATEO BRIDGE ARE REPORTING CLEAR. THE
SLUGGISH MOVEMENT OF STRATUS/FOG OVER SF BAY WITHIN A LIGHT WIND
ENVIRONMENT SUPPORTS TEMPO IFR CIG 12Z-16Z. OTHERWISE VFR TODAY.
SINCE THE WRF MODEL IS UNDER-FORECASTING STRATUS/FOG AM NOT VERY
CERTAIN HOW MUCH CLEARING THERE`LL ON THE OCEAN SIDE OF THE SF
PENINSULA TODAY EXCEPT THAT A HIGHER APRIL SUN ANGLE IS OFTEN
HELPFUL WITH AIR MASS MIXING AND CLEARING. STRATUS RETURNING TONIGHT?
PROBABLY...GIVEN ONSHORE WINDS AND A WEAKENED UPPER LEVEL HIGH BUT
VERY LOW CONFIDENCE TO TRY TO TIME IN THE 12Z TAF.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS CLEARING BY 17Z-18Z THIS
MORNING. LOW CONFIDENCE.

&&

.MARINE...AS OF 4:11 AM PDT SATURDAY...MAINLY LIGHT NORTHWESTERLY
WINDS WILL CONTINUE THROUGH THE BEGINNING OF THE WORK WEEK. NORTHERLY
WINDS WILL INCREASE ONCE AGAIN ACROSS THE COASTAL WATERS BY THE
MIDDLE OF NEXT WEEK. SEAS ARE EXPECTED TO DECREASE AS GENTLER SEAS
MOVE IN FOR THE REMAINDER OF THE WEEKEND.

&&

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

&&

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA








000
FXUS66 KMTR 181154
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
454 AM PDT SAT APR 18 2015

.SYNOPSIS...HIGH PRESSURE ACROSS MUCH OF THE WEST COAST WILL
MAINTAIN ABOVE AVERAGE INLAND TEMPERATURES WITH COOLER CONDITIONS
NEAR THE COAST. CONDITIONS COOL REGION-WIDE EARLY IN THE WEEK WITH
UNSETTLED WEATHER POSSIBLE MID/LATE WEEK AS UPPER LEVEL TROUGHING
DEVELOPS OFF OF THE WEST COAST.

&&

.DISCUSSION...AS OF 04:11 AM PDT SATURDAY...A WEAK MID/UPPER
LEVEL SHORT-WAVE TROUGH APPROACHING THE REGION FROM THE NORTH HAS
HELPED ENHANCE THE MARINE LAYER EARLY THIS MORNING...NOW AROUND
1000 FT. THIS RESULTED IN AN INCREASE IN LOW LEVEL CLOUDS ALONG
THE COAST AND SUPPORTED INLAND PENETRATION INTO THE SALINAS AND
NORTH BAY VALLEYS OVERNIGHT. WHILE THE INCREASED PRESENCE OF THE
MARINE LAYER IS EXPECTED TO KEEP CONDITIONS COOL ALONG THE COAST
TODAY...THE WEAK MID/UPPER LEVEL FEATURE WILL DO LITTLE TO COOL
850MB TEMPERATURES. THUS...INLAND LOCATIONS WILL ONCE AGAIN WARM
INTO THE UPPER 70S TO 80S THIS AFTERNOON. BY SUNDAY...THE WEAK
SHORT-WAVE SYSTEM IS FORECAST TO DEVELOP INTO A CLOSED LOW OFF OF
THE NORTHERN CALIFORNIA COAST. WHILE THIS WILL HELP FURTHER
ENHANCE THE MARINE LAYER THROUGH THE WEEKEND...DRY CONDITIONS AND
WARM INLAND TEMPERATURES ARE EXPECTED TO PERSIST WITH LIMITED
MOISTURE ALOFT.

THE WEAK CUT-OFF LOW PRESSURE SYSTEM WILL LINGER OFF OF THE
CALIFORNIA COAST HEADING INTO EARLY NEXT WEEK WITH AN INCREASE IN
ONSHORE FLOW. THE FORECAST MODELS ALSO INDICATE A SLIGHT INCREASE
IN MID-LEVEL MOISTURE AND INSTABILITY OVER THE SOUTHERN HALF OF
THE REGION ON MONDAY...RESULTING IN THE POTENTIAL FOR AN ISOLATED
SHOWER OR THUNDERSTORM OVER THE HIGHER HILLS SOUTHERN MONTEREY
AND SAN BENITO COUNTIES. OTHERWISE...TEMPERATURES WILL BEGIN TO
COOL REGION-WIDE AHEAD OF A MORE BROAD MID/UPPER LEVEL TROUGH
FORECAST TO APPROACH THE REGION TUESDAY. THE FORECAST MODELS THEN
DEVELOP ANOTHER CLOSED LOW OFF OF THE CALIFORNIA COAST THAT WILL
SLIDE DOWN THE COAST THROUGH MIDWEEK...RESULTING A SLIGHT CHANCE
OF SHOWERS ACROSS THE REGION. HOWEVER...MOISTURE WILL ONCE AGAIN
BE LIMITED AND THE MEDIUM RANGE MODELS KEEP THE BEST CHANCES OF
PRECIPITATION OVER THE HIGHER TERRAIN/MORE INLAND AREAS OF THE
STATE. THUS...NOT EXPECTING ANY ORGANIZED/WIDESPREAD
PRECIPITATION OVER THE REGION AT THIS TIME.

THE MEDIUM RANGE MODELS KEEP AN UNSETTLED PATTERN OVER MUCH OF
THE WEST COAST THROUGH THE REMAINDER OF THE WEEK. THE ECMWF AND
CMC BOTH SHOW A SOMEWHAT STRONGER SYSTEM DROPPING SOUTHWARD ALONG
THE COAST FRIDAY INTO SATURDAY THAT WOULD BRING MORE WIDESPREAD
RAINFALL TO THE REGION. HOWEVER...THERE REMAINS A GREAT DEAL OF
UNCERTAINTY IN THE RUN-TO-RUN AND MODEL-TO-MODEL SOLUTIONS THIS
FAR OUT. WITH ALL THAT SAID...WILL KEEP TEMPERATURES NEAR OR
SLIGHTLY BELOW SEASONAL AVERAGES LATE IN THE FORECAST PERIOD
ALONG WITH A SLIGHT CHANCE OF PRECIPITATION.

&&

.AVIATION...AS OF 4:39 AM PDT SATURDAY...STRATUS AND FOG COVERAGE
IS MORE EXTENSIVE THAN THE WRF MODEL GUIDANCE SHOWS EARLY THIS
MORNING. INCREASES IN SURFACE HUMIDITY OVERNIGHT ON TOP OF CHILLY
SEA SURFACE TEMPS IS RESULTING IN A FAIRLY LARGE AREA OF
STRATUS/FOG FROM POINT ARENA SOUTH TO POINT CONCEPTION. AREA
PROFILER DATA INDICATING THE MARINE LAYER DEPTH IS NEAR 1000 FEET.
THE SFO-SAC PRESS GRADIENT IS 2 MB WHILE THE ACV-SFO IS 2.4. THE
ACV-SFO IS FORECASTED TO WEAKEN TODAY WHILE THE SFO-SAC GRADIENT
REACHES 3 MB BY MID-LATE AFTERNOON FURTHER STRENGTHENING THE
ONSHORE WINDS. THE LOW LEVEL TEMPS WILL INCREASE BY 1 DEG C
THROUGH TODAY AS WELL WHICH WILL CONTINUE TO SUPPORT THE MARINE
LAYER INVERSION.

VICINITY OF KSFO...THE SATELLITE STRATUS/FOG PRODUCT SHOWS A CLEAR
SKY...BUT LOW CLOUD PATCHES ARE NOT VERY FAR AWAY FROM THE SFO
APPROACH. IT`S A DIFFICULT FORECAST THIS MORNING...NOT SO MUCH
THAT THE MARINE LAYER INVERSION AT 1000 FEET AND LIGHT WESTERLY
SURFACE WIND DO NOT SUPPORT STRATUS AND/OR FOG ADVECTION THROUGH
THE SAN BRUNO GAP...BUT WILL NEED TO WATCH THOSE PATCHY LOW CLOUDS
THAT ARE SLOWLY APPROACHING THE TERMINAL AND APPROACH FROM THE
SE-E. SO FAR KSFO AND SAN MATEO BRIDGE ARE REPORTING CLEAR. THE
SLUGGISH MOVEMENT OF STRATUS/FOG OVER SF BAY WITHIN A LIGHT WIND
ENVIRONMENT SUPPORTS TEMPO IFR CIG 12Z-16Z. OTHERWISE VFR TODAY.
SINCE THE WRF MODEL IS UNDER-FORECASTING STRATUS/FOG AM NOT VERY
CERTAIN HOW MUCH CLEARING THERE`LL ON THE OCEAN SIDE OF THE SF
PENINSULA TODAY EXCEPT THAT A HIGHER APRIL SUN ANGLE IS OFTEN
HELPFUL WITH AIR MASS MIXING AND CLEARING. STRATUS RETURNING TONIGHT?
PROBABLY...GIVEN ONSHORE WINDS AND A WEAKENED UPPER LEVEL HIGH BUT
VERY LOW CONFIDENCE TO TRY TO TIME IN THE 12Z TAF.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS CLEARING BY 17Z-18Z THIS
MORNING. LOW CONFIDENCE.

&&

.MARINE...AS OF 4:11 AM PDT SATURDAY...MAINLY LIGHT NORTHWESTERLY
WINDS WILL CONTINUE THROUGH THE BEGINNING OF THE WORK WEEK. NORTHERLY
WINDS WILL INCREASE ONCE AGAIN ACROSS THE COASTAL WATERS BY THE
MIDDLE OF NEXT WEEK. SEAS ARE EXPECTED TO DECREASE AS GENTLER SEAS
MOVE IN FOR THE REMAINDER OF THE WEEKEND.

&&

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

&&

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA








000
FXUS66 KMTR 181154
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
454 AM PDT SAT APR 18 2015

.SYNOPSIS...HIGH PRESSURE ACROSS MUCH OF THE WEST COAST WILL
MAINTAIN ABOVE AVERAGE INLAND TEMPERATURES WITH COOLER CONDITIONS
NEAR THE COAST. CONDITIONS COOL REGION-WIDE EARLY IN THE WEEK WITH
UNSETTLED WEATHER POSSIBLE MID/LATE WEEK AS UPPER LEVEL TROUGHING
DEVELOPS OFF OF THE WEST COAST.

&&

.DISCUSSION...AS OF 04:11 AM PDT SATURDAY...A WEAK MID/UPPER
LEVEL SHORT-WAVE TROUGH APPROACHING THE REGION FROM THE NORTH HAS
HELPED ENHANCE THE MARINE LAYER EARLY THIS MORNING...NOW AROUND
1000 FT. THIS RESULTED IN AN INCREASE IN LOW LEVEL CLOUDS ALONG
THE COAST AND SUPPORTED INLAND PENETRATION INTO THE SALINAS AND
NORTH BAY VALLEYS OVERNIGHT. WHILE THE INCREASED PRESENCE OF THE
MARINE LAYER IS EXPECTED TO KEEP CONDITIONS COOL ALONG THE COAST
TODAY...THE WEAK MID/UPPER LEVEL FEATURE WILL DO LITTLE TO COOL
850MB TEMPERATURES. THUS...INLAND LOCATIONS WILL ONCE AGAIN WARM
INTO THE UPPER 70S TO 80S THIS AFTERNOON. BY SUNDAY...THE WEAK
SHORT-WAVE SYSTEM IS FORECAST TO DEVELOP INTO A CLOSED LOW OFF OF
THE NORTHERN CALIFORNIA COAST. WHILE THIS WILL HELP FURTHER
ENHANCE THE MARINE LAYER THROUGH THE WEEKEND...DRY CONDITIONS AND
WARM INLAND TEMPERATURES ARE EXPECTED TO PERSIST WITH LIMITED
MOISTURE ALOFT.

THE WEAK CUT-OFF LOW PRESSURE SYSTEM WILL LINGER OFF OF THE
CALIFORNIA COAST HEADING INTO EARLY NEXT WEEK WITH AN INCREASE IN
ONSHORE FLOW. THE FORECAST MODELS ALSO INDICATE A SLIGHT INCREASE
IN MID-LEVEL MOISTURE AND INSTABILITY OVER THE SOUTHERN HALF OF
THE REGION ON MONDAY...RESULTING IN THE POTENTIAL FOR AN ISOLATED
SHOWER OR THUNDERSTORM OVER THE HIGHER HILLS SOUTHERN MONTEREY
AND SAN BENITO COUNTIES. OTHERWISE...TEMPERATURES WILL BEGIN TO
COOL REGION-WIDE AHEAD OF A MORE BROAD MID/UPPER LEVEL TROUGH
FORECAST TO APPROACH THE REGION TUESDAY. THE FORECAST MODELS THEN
DEVELOP ANOTHER CLOSED LOW OFF OF THE CALIFORNIA COAST THAT WILL
SLIDE DOWN THE COAST THROUGH MIDWEEK...RESULTING A SLIGHT CHANCE
OF SHOWERS ACROSS THE REGION. HOWEVER...MOISTURE WILL ONCE AGAIN
BE LIMITED AND THE MEDIUM RANGE MODELS KEEP THE BEST CHANCES OF
PRECIPITATION OVER THE HIGHER TERRAIN/MORE INLAND AREAS OF THE
STATE. THUS...NOT EXPECTING ANY ORGANIZED/WIDESPREAD
PRECIPITATION OVER THE REGION AT THIS TIME.

THE MEDIUM RANGE MODELS KEEP AN UNSETTLED PATTERN OVER MUCH OF
THE WEST COAST THROUGH THE REMAINDER OF THE WEEK. THE ECMWF AND
CMC BOTH SHOW A SOMEWHAT STRONGER SYSTEM DROPPING SOUTHWARD ALONG
THE COAST FRIDAY INTO SATURDAY THAT WOULD BRING MORE WIDESPREAD
RAINFALL TO THE REGION. HOWEVER...THERE REMAINS A GREAT DEAL OF
UNCERTAINTY IN THE RUN-TO-RUN AND MODEL-TO-MODEL SOLUTIONS THIS
FAR OUT. WITH ALL THAT SAID...WILL KEEP TEMPERATURES NEAR OR
SLIGHTLY BELOW SEASONAL AVERAGES LATE IN THE FORECAST PERIOD
ALONG WITH A SLIGHT CHANCE OF PRECIPITATION.

&&

.AVIATION...AS OF 4:39 AM PDT SATURDAY...STRATUS AND FOG COVERAGE
IS MORE EXTENSIVE THAN THE WRF MODEL GUIDANCE SHOWS EARLY THIS
MORNING. INCREASES IN SURFACE HUMIDITY OVERNIGHT ON TOP OF CHILLY
SEA SURFACE TEMPS IS RESULTING IN A FAIRLY LARGE AREA OF
STRATUS/FOG FROM POINT ARENA SOUTH TO POINT CONCEPTION. AREA
PROFILER DATA INDICATING THE MARINE LAYER DEPTH IS NEAR 1000 FEET.
THE SFO-SAC PRESS GRADIENT IS 2 MB WHILE THE ACV-SFO IS 2.4. THE
ACV-SFO IS FORECASTED TO WEAKEN TODAY WHILE THE SFO-SAC GRADIENT
REACHES 3 MB BY MID-LATE AFTERNOON FURTHER STRENGTHENING THE
ONSHORE WINDS. THE LOW LEVEL TEMPS WILL INCREASE BY 1 DEG C
THROUGH TODAY AS WELL WHICH WILL CONTINUE TO SUPPORT THE MARINE
LAYER INVERSION.

VICINITY OF KSFO...THE SATELLITE STRATUS/FOG PRODUCT SHOWS A CLEAR
SKY...BUT LOW CLOUD PATCHES ARE NOT VERY FAR AWAY FROM THE SFO
APPROACH. IT`S A DIFFICULT FORECAST THIS MORNING...NOT SO MUCH
THAT THE MARINE LAYER INVERSION AT 1000 FEET AND LIGHT WESTERLY
SURFACE WIND DO NOT SUPPORT STRATUS AND/OR FOG ADVECTION THROUGH
THE SAN BRUNO GAP...BUT WILL NEED TO WATCH THOSE PATCHY LOW CLOUDS
THAT ARE SLOWLY APPROACHING THE TERMINAL AND APPROACH FROM THE
SE-E. SO FAR KSFO AND SAN MATEO BRIDGE ARE REPORTING CLEAR. THE
SLUGGISH MOVEMENT OF STRATUS/FOG OVER SF BAY WITHIN A LIGHT WIND
ENVIRONMENT SUPPORTS TEMPO IFR CIG 12Z-16Z. OTHERWISE VFR TODAY.
SINCE THE WRF MODEL IS UNDER-FORECASTING STRATUS/FOG AM NOT VERY
CERTAIN HOW MUCH CLEARING THERE`LL ON THE OCEAN SIDE OF THE SF
PENINSULA TODAY EXCEPT THAT A HIGHER APRIL SUN ANGLE IS OFTEN
HELPFUL WITH AIR MASS MIXING AND CLEARING. STRATUS RETURNING TONIGHT?
PROBABLY...GIVEN ONSHORE WINDS AND A WEAKENED UPPER LEVEL HIGH BUT
VERY LOW CONFIDENCE TO TRY TO TIME IN THE 12Z TAF.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...IFR CIGS CLEARING BY 17Z-18Z THIS
MORNING. LOW CONFIDENCE.

&&

.MARINE...AS OF 4:11 AM PDT SATURDAY...MAINLY LIGHT NORTHWESTERLY
WINDS WILL CONTINUE THROUGH THE BEGINNING OF THE WORK WEEK. NORTHERLY
WINDS WILL INCREASE ONCE AGAIN ACROSS THE COASTAL WATERS BY THE
MIDDLE OF NEXT WEEK. SEAS ARE EXPECTED TO DECREASE AS GENTLER SEAS
MOVE IN FOR THE REMAINDER OF THE WEEKEND.

&&

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

&&

$$

PUBLIC FORECAST: RGASS
AVIATION/MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSBAYAREA
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA









000
FXUS66 KMTR 181114
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
414 AM PDT SAT APR 18 2015

.SYNOPSIS...HIGH PRESSURE ACROSS MUCH OF THE WEST COAST WILL
MAINTAIN ABOVE AVERAGE INLAND TEMPERATURES WITH COOLER CONDITIONS
NEAR THE COAST. CONDITIONS COOL REGION-WIDE EARLY IN THE WEEK WITH
UNSETTLED WEATHER POSSIBLE MID/LATE WEEK AS UPPER LEVEL TROUGHING
DEVELOPS OFF OF THE WEST COAST.

&&

.DISCUSSION...AS OF 04:11 AM PDT SATURDAY...A WEAK MID/UPPER
LEVEL SHORT-WAVE TROUGH APPROACHING THE REGION FROM THE NORTH HAS
HELPED ENHANCE THE MARINE LAYER EARLY THIS MORNING...NOW AROUND
1000 FT. THIS RESULTED IN AN INCREASE IN LOW LEVEL CLOUDS ALONG
THE COAST AND SUPPORTED INLAND PENETRATION INTO THE SALINAS AND
NORTH BAY VALLEYS OVERNIGHT. WHILE THE INCREASED PRESENCE OF THE
MARINE LAYER IS EXPECTED TO KEEP CONDITIONS COOL ALONG THE COAST
TODAY...THE WEAK MID/UPPER LEVEL FEATURE WILL DO LITTLE TO COOL
850MB TEMPERATURES. THUS...INLAND LOCATIONS WILL ONCE AGAIN WARM
INTO THE UPPER 70S TO 80S THIS AFTERNOON. BY SUNDAY...THE WEAK
SHORT-WAVE SYSTEM IS FORECAST TO DEVELOP INTO A CLOSED LOW OFF OF
THE NORTHERN CALIFORNIA COAST. WHILE THIS WILL HELP FURTHER
ENHANCE THE MARINE LAYER THROUGH THE WEEKEND...DRY CONDITIONS AND
WARM INLAND TEMPERATURES ARE EXPECTED TO PERSIST WITH LIMITED
MOISTURE ALOFT.

THE WEAK CUT-OFF LOW PRESSURE SYSTEM WILL LINGER OFF OF THE
CALIFORNIA COAST HEADING INTO EARLY NEXT WEEK WITH AN INCREASE IN
ONSHORE FLOW. THE FORECAST MODELS ALSO INDICATE A SLIGHT INCREASE
IN MID-LEVEL MOISTURE AND INSTABILITY OVER THE SOUTHERN HALF OF
THE REGION ON MONDAY...RESULTING IN THE POTENTIAL FOR AN ISOLATED
SHOWER OR THUNDERSTORM OVER THE HIGHER HILLS SOUTHERN MONTEREY
AND SAN BENITO COUNTIES. OTHERWISE...TEMPERATURES WILL BEGIN TO
COOL REGION-WIDE AHEAD OF A MORE BROAD MID/UPPER LEVEL TROUGH
FORECAST TO APPROACH THE REGION TUESDAY. THE FORECAST MODELS THEN
DEVELOP ANOTHER CLOSED LOW OFF OF THE CALIFORNIA COAST THAT WILL
SLIDE DOWN THE COAST THROUGH MIDWEEK...RESULTING A SLIGHT CHANCE
OF SHOWERS ACROSS THE REGION. HOWEVER...MOISTURE WILL ONCE AGAIN
BE LIMITED AND THE MEDIUM RANGE MODELS KEEP THE BEST CHANCES OF
PRECIPITATION OVER THE HIGHER TERRAIN/MORE INLAND AREAS OF THE
STATE. THUS...NOT EXPECTING ANY ORGANIZED/WIDESPREAD
PRECIPITATION OVER THE REGION AT THIS TIME.

THE MEDIUM RANGE MODELS KEEP AN UNSETTLED PATTERN OVER MUCH OF
THE WEST COAST THROUGH THE REMAINDER OF THE WEEK. THE ECMWF AND
CMC BOTH SHOW A SOMEWHAT STRONGER SYSTEM DROPPING SOUTHWARD ALONG
THE COAST FRIDAY INTO SATURDAY THAT WOULD BRING MORE WIDESPREAD
RAINFALL TO THE REGION. HOWEVER...THERE REMAINS A GREAT DEAL OF
UNCERTAINTY IN THE RUN-TO-RUN AND MODEL-TO-MODEL SOLUTIONS THIS
FAR OUT. WITH ALL THAT SAID...WILL KEEP TEMPERATURES NEAR OR
SLIGHTLY BELOW SEASONAL AVERAGES LATE IN THE FORECAST PERIOD
ALONG WITH A SLIGHT CHANCE OF PRECIPITATION.

&&

.AVIATION...AS OF 10:50 PM PDT FRIDAY...THE CURRENT IR SATELLITE
FOG PRODUCT IS SHOWING STRATUS MOVING IN ALONG THE CENTRAL
CALIFORNIA COAST THIS EVENING PUSHING INTO PORTIONS OF THE SAN
FRANCISCO BAY AND MONTEREY BAY. THE FORT ORD PROFILER CONTINUES TO
SHOW A MARINE LAYER APPROXIMATELY 800 FEET DEEP. WITH SUFFICIENT
ONSHORE FLOW THE SHALLOW MARINE LAYER WILL CONTINUE TO ADVECT INTO
THE SAN FRANCISCO BAY AREA RESULTING IN LOW CIGS OVERNIGHT. THE
WRF HIGH RES FORECAST MODEL DEVELOPS AN EDDY IN MONTEREY BAY WHICH
MAY KEEP STRATUS OUT OF THE MONTEREY BAY AREA TERMINALS OVERNIGHT.

VICINITY OF KSFO...VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH
AROUND 1200Z AT WHICH POINT BKN-OVC008 WILL BE POSSIBLE. FIRST
GUESS AT THE MORNING BURN OFF IS 1700Z.

CONFIDENCE IS MODERATE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR IS EXPECTED TO PREVAIL THROUGH
THE NEXT 24 HOURS. HOWEVER...A PERIOD OF LOW CIGS BKN-OVC008 WILL
BE POSSIBLE AFTER MIDNIGHT.

CONFIDENCE IS MODERATE.

&&

.MARINE...AS OF 04:11 AM PDT SATURDAY...MAINLY LIGHT NORTHWESTERLY
WINDS WILL CONTINUE THROUGH THE BEGINNING OF THE WORK WEEK.
NORTHERLY WINDS WILL INCREASE ONCE AGAIN ACROSS THE COASTAL WATERS
BY THE MIDDLE OF NEXT WEEK. SEAS ARE EXPECTED TO DECREASE AS
GENTLER SEAS MOVE IN FOR THE REMAINDER OF THE WEEKEND.

&&

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

&&

$$

PUBLIC FORECAST: RGASS
AVIATION: LARRY
MARINE: CANEPA

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000
FXUS66 KMTR 181114
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
414 AM PDT SAT APR 18 2015

.SYNOPSIS...HIGH PRESSURE ACROSS MUCH OF THE WEST COAST WILL
MAINTAIN ABOVE AVERAGE INLAND TEMPERATURES WITH COOLER CONDITIONS
NEAR THE COAST. CONDITIONS COOL REGION-WIDE EARLY IN THE WEEK WITH
UNSETTLED WEATHER POSSIBLE MID/LATE WEEK AS UPPER LEVEL TROUGHING
DEVELOPS OFF OF THE WEST COAST.

&&

.DISCUSSION...AS OF 04:11 AM PDT SATURDAY...A WEAK MID/UPPER
LEVEL SHORT-WAVE TROUGH APPROACHING THE REGION FROM THE NORTH HAS
HELPED ENHANCE THE MARINE LAYER EARLY THIS MORNING...NOW AROUND
1000 FT. THIS RESULTED IN AN INCREASE IN LOW LEVEL CLOUDS ALONG
THE COAST AND SUPPORTED INLAND PENETRATION INTO THE SALINAS AND
NORTH BAY VALLEYS OVERNIGHT. WHILE THE INCREASED PRESENCE OF THE
MARINE LAYER IS EXPECTED TO KEEP CONDITIONS COOL ALONG THE COAST
TODAY...THE WEAK MID/UPPER LEVEL FEATURE WILL DO LITTLE TO COOL
850MB TEMPERATURES. THUS...INLAND LOCATIONS WILL ONCE AGAIN WARM
INTO THE UPPER 70S TO 80S THIS AFTERNOON. BY SUNDAY...THE WEAK
SHORT-WAVE SYSTEM IS FORECAST TO DEVELOP INTO A CLOSED LOW OFF OF
THE NORTHERN CALIFORNIA COAST. WHILE THIS WILL HELP FURTHER
ENHANCE THE MARINE LAYER THROUGH THE WEEKEND...DRY CONDITIONS AND
WARM INLAND TEMPERATURES ARE EXPECTED TO PERSIST WITH LIMITED
MOISTURE ALOFT.

THE WEAK CUT-OFF LOW PRESSURE SYSTEM WILL LINGER OFF OF THE
CALIFORNIA COAST HEADING INTO EARLY NEXT WEEK WITH AN INCREASE IN
ONSHORE FLOW. THE FORECAST MODELS ALSO INDICATE A SLIGHT INCREASE
IN MID-LEVEL MOISTURE AND INSTABILITY OVER THE SOUTHERN HALF OF
THE REGION ON MONDAY...RESULTING IN THE POTENTIAL FOR AN ISOLATED
SHOWER OR THUNDERSTORM OVER THE HIGHER HILLS SOUTHERN MONTEREY
AND SAN BENITO COUNTIES. OTHERWISE...TEMPERATURES WILL BEGIN TO
COOL REGION-WIDE AHEAD OF A MORE BROAD MID/UPPER LEVEL TROUGH
FORECAST TO APPROACH THE REGION TUESDAY. THE FORECAST MODELS THEN
DEVELOP ANOTHER CLOSED LOW OFF OF THE CALIFORNIA COAST THAT WILL
SLIDE DOWN THE COAST THROUGH MIDWEEK...RESULTING A SLIGHT CHANCE
OF SHOWERS ACROSS THE REGION. HOWEVER...MOISTURE WILL ONCE AGAIN
BE LIMITED AND THE MEDIUM RANGE MODELS KEEP THE BEST CHANCES OF
PRECIPITATION OVER THE HIGHER TERRAIN/MORE INLAND AREAS OF THE
STATE. THUS...NOT EXPECTING ANY ORGANIZED/WIDESPREAD
PRECIPITATION OVER THE REGION AT THIS TIME.

THE MEDIUM RANGE MODELS KEEP AN UNSETTLED PATTERN OVER MUCH OF
THE WEST COAST THROUGH THE REMAINDER OF THE WEEK. THE ECMWF AND
CMC BOTH SHOW A SOMEWHAT STRONGER SYSTEM DROPPING SOUTHWARD ALONG
THE COAST FRIDAY INTO SATURDAY THAT WOULD BRING MORE WIDESPREAD
RAINFALL TO THE REGION. HOWEVER...THERE REMAINS A GREAT DEAL OF
UNCERTAINTY IN THE RUN-TO-RUN AND MODEL-TO-MODEL SOLUTIONS THIS
FAR OUT. WITH ALL THAT SAID...WILL KEEP TEMPERATURES NEAR OR
SLIGHTLY BELOW SEASONAL AVERAGES LATE IN THE FORECAST PERIOD
ALONG WITH A SLIGHT CHANCE OF PRECIPITATION.

&&

.AVIATION...AS OF 10:50 PM PDT FRIDAY...THE CURRENT IR SATELLITE
FOG PRODUCT IS SHOWING STRATUS MOVING IN ALONG THE CENTRAL
CALIFORNIA COAST THIS EVENING PUSHING INTO PORTIONS OF THE SAN
FRANCISCO BAY AND MONTEREY BAY. THE FORT ORD PROFILER CONTINUES TO
SHOW A MARINE LAYER APPROXIMATELY 800 FEET DEEP. WITH SUFFICIENT
ONSHORE FLOW THE SHALLOW MARINE LAYER WILL CONTINUE TO ADVECT INTO
THE SAN FRANCISCO BAY AREA RESULTING IN LOW CIGS OVERNIGHT. THE
WRF HIGH RES FORECAST MODEL DEVELOPS AN EDDY IN MONTEREY BAY WHICH
MAY KEEP STRATUS OUT OF THE MONTEREY BAY AREA TERMINALS OVERNIGHT.

VICINITY OF KSFO...VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH
AROUND 1200Z AT WHICH POINT BKN-OVC008 WILL BE POSSIBLE. FIRST
GUESS AT THE MORNING BURN OFF IS 1700Z.

CONFIDENCE IS MODERATE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR IS EXPECTED TO PREVAIL THROUGH
THE NEXT 24 HOURS. HOWEVER...A PERIOD OF LOW CIGS BKN-OVC008 WILL
BE POSSIBLE AFTER MIDNIGHT.

CONFIDENCE IS MODERATE.

&&

.MARINE...AS OF 04:11 AM PDT SATURDAY...MAINLY LIGHT NORTHWESTERLY
WINDS WILL CONTINUE THROUGH THE BEGINNING OF THE WORK WEEK.
NORTHERLY WINDS WILL INCREASE ONCE AGAIN ACROSS THE COASTAL WATERS
BY THE MIDDLE OF NEXT WEEK. SEAS ARE EXPECTED TO DECREASE AS
GENTLER SEAS MOVE IN FOR THE REMAINDER OF THE WEEKEND.

&&

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

&&

$$

PUBLIC FORECAST: RGASS
AVIATION: LARRY
MARINE: CANEPA

VISIT US AT WEATHER.GOV/SANFRANCISCO

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000
FXUS66 KMTR 180548
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1048 PM PDT FRI APR 17 2015

.SYNOPSIS...HIGH PRESSURE THIS WEEKEND WILL BRING SEASONABLE
TEMPERATURES WITH TRANQUIL CONDITIONS. BY MONDAY SOME INSTABILITY
WILL DEVELOP OVER THE REGION...PRODUCING CUMULUS CLOUDS AND A
SLIGHT CHANCE OF AN ISOLATED SHOWER OR THUNDERSTORM ACROSS SOME OF
THE REMOTE INTERIOR HILLS. BY TUESDAY AND WEDNESDAY AN UPPER LOW
WILL APPROACH...RESULTING IN A COOLING TREND ALONG WITH A SLIGHT
CHANCE OF SHOWERS...MAINLY OVER THE HILLS.

&&

.DISCUSSION...AS OF 8:40 PM PDT FRIDAY...A SHALLOW MARINE LAYER
DEVELOPED TODAY...RESULTING IN UP TO TEN DEGREES OF COOLING NEAR
THE IMMEDIATE COAST...MAINLY FROM SAN MATEO COUNTY NORTHWARD. BUT
MOST AREAS AWAY FROM THE COAST REMAINED ISOLATED FROM THE COOLING
EFFECTS OF THE SHALLOW MARINE LAYER AND LIGHT ONSHORE FLOW AND
ENDED UP BEING AS WARM AS YESTERDAY...OR EVEN A BIT WARMER. A
RECORD HIGH OF 86 OCCURRED IN SANTA CRUZ TODAY AND SALINAS TIED
THEIR RECORD HIGH FOR THE DAY WITH AN 81.

A WEAK SHORTWAVE TROUGH IS CURRENTLY MOVING INLAND ACROSS THE PAC
NW. THIS WEAK UPPER LEVEL DISTURBANCE IS FORECAST TO DROP SOUTH
INTO NORTHERN CA ON SATURDAY AND THEN FORM A WEAK CUTOFF LOW OFF
THE NORTHERN CA COAST BY LATE SUNDAY. THIS SYSTEM IS EXPECTED TO BE
TOO WEAK AND DRY TO GENERATE ANY PRECIP OVER OUR AREA THROUGH THE
WEEKEND...BUT IT WILL LIKELY RESULT IN AN INCREASE IN THE DEPTH
OF THE MARINE LAYER AND THUS AT LEAST SLIGHT COOLING OVER THE
NEXT TWO DAYS. ONSHORE FLOW IS FORECAST TO REMAIN WEAK THROUGH THE
WEEKEND AND SO INLAND AREAS WILL PROBABLY SEE ONLY MODEST COOLING.
THE UPSHOT IS THAT COASTAL AREAS CAN EXPECT AREAS OF LOW CLOUDS
AND FOG THIS WEEKEND...BUT INLAND AREAS SHOULD REMAIN MOSTLY
CLEAR AND WARM. BY MONDAY ONSHORE FLOW IS EXPECTED TO INCREASE
WHICH WILL BE THE START OF A REGION-WIDE COOLING TREND. IN
ADDITION...MOISTURE IS FORECAST TO INCREASE SOMEWHAT ACROSS THE
SOUTHERN PART OF OUR FORECAST AREA ON MONDAY AND THERE MAY BE JUST
ENOUGH INSTABILITY OVER THE HIGHER HILLS BY THAT AFTERNOON TO
GENERATE ISOLATED SHOWERS AND THUNDERSTORMS ACROSS PORTIONS OF
SOUTHERN SAN BENITO COUNTY.

THE COOLING TREND IS EXPECTED TO RAMP UP ON TUESDAY AS AN UPPER
TROUGH APPROACHES FROM THE NW. THAT TROUGH IS THEN FORECAST TO DIG
SOUTH ALONG THE CA COAST ON TUESDAY NIGHT AND WEDNESDAY...FORMING
AN UPPER LOW NEAR THE CENTRAL CA COAST BY LATE WEDNESDAY. SHOWER
CHANCES WILL SPREAD FROM NORTH TO SOUTH ACROSS OUR REGION FROM
TUESDAY INTO WEDNESDAY...BUT THE MEDIUM RANGE MODELS AGREE THAT
THE BULK OF THE PRECIPITATION WITH THIS MIDWEEK SYSTEM WILL FALL
OVER THE HIGHER MOUNTAINS OF CA (E.G., SIERRA NEVADA).

THE PATTERN IS FORECAST TO REMAIN UNSETTLED INTO LATE NEXT
WEEK...BUT THE LIKELIHOOD OF RAINFALL OF ANY SIGNIFICANCE IS
DIFFICULT TO PREDICT AT THIS POINT GIVEN MODEL DIFFERENCES. THE
12Z ECMWF OFFERS THE BEST HOPE OF WIDESPREAD RAINFALL...SHOWING A
POTENT AND RELATIVELY WET LITTLE SYSTEM SWEEPING ACROSS CENTRAL CA
FROM LATE NEXT FRIDAY THROUGH SATURDAY MORNING.

&&

.AVIATION...AS OF 10:50 PM PDT FRIDAY...THE CURRENT IR SATELLITE
FOG PRODUCT IS SHOWING STRATUS MOVING IN ALONG THE CENTRAL
CALIFORNIA COAST THIS EVENING PUSHING INTO PORTIONS OF THE SAN
FRANCISCO BAY AND MONTEREY BAY. THE FORT ORD PROFILER CONTINUES TO
SHOW A MARINE LAYER APPROXIMATELY 800 FEET DEEP. WITH SUFFICIENT
ONSHORE FLOW THE SHALLOW MARINE LAYER WILL CONTINUE TO ADVECT INTO
THE SAN FRANCISCO BAY AREA RESULTING IN LOW CIGS OVERNIGHT. THE
WRF HIGH RES FORECAST MODEL DEVELOPS AN EDDY IN MONTEREY BAY WHICH
MAY KEEP STRATUS OUT OF THE MONTEREY BAY AREA TERMINALS OVERNIGHT.

VICINITY OF KSFO...VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH
AROUND 1200Z AT WHICH POINT BKN-OVC008 WILL BE POSSIBLE. FIRST
GUESS AT THE MORNING BURN OFF IS 1700Z.

CONFIDENCE IS MODERATE.

SFO BRIDGE APPROACH...SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...VFR IS EXPECTED TO PREVAIL THROUGH
THE NEXT 24 HOURS. HOWEVER...A PERIOD OF LOW CIGS BKN-OVC008 WILL
BE POSSIBLE AFTER MIDNIGHT.

CONFIDENCE IS MODERATE.

&&

.CLIMATE...RECORD HIGH TEMPERATURES FOR FRIDAY (4/17)
ALONG WITH THE MOST RECENT DATE IT OCCURRED.

SF BAY AREA
.LOCATION.................4/17
 KENTFIELD...............89/1999
 SAN RAFAEL..............88/1954
 NAPA....................88/1954
 SAN FRANCISCO...........79/1954
 SFO AIRPORT.............82/1954
 OAKLAND (DOWNTOWN)......78/1977
 OAKLAND AIRPORT.........87/1954
 RICHMOND................86/1954
 LIVERMORE...............90/1966
 MOFFETT FIELD...........83/1954
 SAN JOSE................92/1999
 GILROY..................92/1999

MONTEREY BAY AREA
.LOCATION.................4/17
 MONTEREY................80/1952
 SANTA CRUZ..............84/1938
 SALINAS.................81/1999
 SALINAS AIRPORT.........87/1952
 KING CITY...............98/1954

&&

.MARINE...AS OF 10:42 PM PDT FRIDAY...A BROAD THERMAL TROUGH
POSITIONED OVER MUCH OF CALIFORNIA WILL MAINTAIN GENERALLY LIGHT
TO MODERATE WESTERLY WINDS THROUGH THE BEGINNING OF THE WORK WEEK.
WINDS WILL BE LOCALLY STRONGER NORTH OF POINT REYES...ESPECIALLY
OVER THE OUTER WATERS. NORTHERLY WINDS WILL INCREASE ONCE AGAIN
ACROSS THE COASTAL WATERS BY MID WEEK. SEAS ARE EXPECTED TO
DECREASE OVERNIGHT AS GENTLER SEAS MOVE IN FOR THE REMAINDER OF
THE WEEKEND.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TNGT...SCA...PT ARENA TO PT REYES 10-60 NM
             SCA...ROUGH BAR ADVISORY FOR SF BAR UNTIL 6 AM

&&

$$

PUBLIC FORECAST: DYKEMA
AVIATION/MARINE: LARRY
CLIMATE: HENDERSON/BELL

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