Weather Service Report


552 
FXUS66 KMTR 211721
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
1021 AM PDT TUE APR 21 2015

.SYNOPSIS...WEATHER CONDITIONS OVER THE REGION TODAY WILL BE A
NEAR REPEAT OF THOSE ON MONDAY WITH A DEEP MARINE LAYER IN PLACE.
A SLIGHT INLAND COOLING TREND IS THEN EXPECTED THROUGH LATE WEEK
AS WEAK UPPER LEVEL DISTURBANCES MOVE THROUGH THE STATE. THESE
WEAK WEATHER SYSTEMS WILL RESULT IN A SLIGHT CHANCE OF SHOWERS AT
TIMES THROUGH THE REMAINDER OF THE WEEK...PRIMARILY OVER THE
MOUNTAINS.

&&

.DISCUSSION...AS OF 8:45 AM PDT TUESDAY...ANOTHER ROUND OF
WIDESPREAD MORNING CLOUDS WITH A MODERATE WESTERLY SURFACE
GRADIENT PLUS A VERY DEEP MARINE LAYER -- NOW WELL OVER 3000 FEET
ACCORDING TO THE FORT ORD PROFILER. CLOUDS SHOULD BURN-OFF FOR
INLAND SPOTS BY LATER THIS MORNING WHILE COASTAL AREAS COULD SEE
CLOUDS THROUGH MOST IF NOT ALL OF THE DAY. HIGHS WILL RANGE FROM
THE UPPER 50S TO MID 60S AT THE COAST UP TO THE MID 60S TO MID 70S FOR
INLAND LOCATIONS. 

OVERALL APPEARS TO BE A CONTINUED QUIET WEEK FOR OUR CWA WITH
TEMPERATURES RUNNING CLOSE TO NORMAL. NO UPDATES EXPECTED.

.PREVIOUS DISCUSSION...THE PRESENCE OF A RELATIVELY DEEP MARINE LAYER ONCE
AGAIN ALLOWED FOR LOW CLOUDS TO DEVELOP WELL INLAND EARLY THIS
MORNING. AS A RESULT...TEMPERATURES ARE SIMILAR TO 24 HOURS
AGO...GENERALLY IN THE LOW/MID 50S. A WEAK UPPER LEVEL LOW REMAINS
TO OUR SOUTH AND WILL MOVE INTO SOUTHERN CALIFORNIA TODAY WHILE A
MID/UPPER LEVEL TROUGH APPROACHES THE PACIFIC NORTHWEST. WITH
LITTLE CHANGE IN THE OVERALL PATTERN ALOFT...WEATHER CONDITIONS
WILL BE SIMILAR TO THOSE YESTERDAY. WHILE INLAND AREAS ARE
EXPECTED TO SEE CLEARING BY LATE MORNING/EARLY AFTERNOON...MANY
COASTAL LOCATIONS WILL ONCE AGAIN REMAIN BENEATH LOW CLOUD COVER
THROUGH MUCH OF THE DAY. IN ADDITION...THE FORECAST MODELS
CONTINUE TO SUGGEST THE BEST CHANCES FOR CONVECTION TODAY WILL BE
WELL INLAND OVER THE HIGHER TERRAIN...WITH JUST AN OUTSIDE CHANCE
OVER SOUTHERN MONTEREY AND SAN BENITO COUNTIES.

THE APPROACHING TROUGH TO OUR NORTHWEST WILL PUSH INLAND OVER
NORTHERN CALIFORNIA THROUGH MIDWEEK AND BRING WITH IT A SLIGHTLY
COOLER AIRMASS. THIS TOO SHOULD HELP BREAK DOWN THE MARINE LAYER
TO SOME EXTENT BY WEDNESDAY...ESPECIALLY OVER THE NORTHERN HALF
OF THE REGION. MEANWHILE...THE NAM AND OTHER HIGHER RESOLUTION
MODELS MAINTAIN DEEP BOUNDARY LAYER MOISTURE ACROSS MUCH OF THE
CENTRAL COAST. REGARDLESS...DAYTIME TEMPERATURES WILL COOL TO
NEAR SEASONAL AVERAGES REGION-WIDE THROUGH LATE WEEK. WITH BROAD
MID/UPPER LEVEL TROFING FORECAST OVER THE STATE THROUGH LATE
WEEK...CANNOT RULE OUT A FEW SHOWERS OVER THE INLAND
HILLS/MOUNTAINS. YET MOST LOCATIONS WILL REMAIN DRY THROUGH THE
REMAINDER OF THE WORK WEEK.

A SHORT-WAVE DISTURBANCE IS THEN FORECAST TO SWEEP THROUGH ON
FRIDAY AS THE MAIN UPPER LEVEL TROUGH FINALLY SHIFTS INLAND. THIS
WILL COOL TEMPERATURES BY A FEW DEGREES FOR FRIDAY WITH ANOTHER
SLIGHT CHANCE OF SHOWERS OVER HIGHER ELEVATIONS ACROSS THE
CENTRAL COAST. OTHERWISE...THIS SYSTEM WILL LIKELY PASS ACROSS
THE REGION WITHOUT MUCH FANFARE.

THE MEDIUM RANGE FORECAST MODELS NOW GENERALLY AGREE IN WEAK
RIDGING OVER MUCH OF THE STATE THIS WEEKEND INTO EARLY NEXT WEEK.
AS A RESULT...WILL KEEP GENERALLY DRY CONDITIONS REGION-WIDE
ALONG WITH INLAND WARMING FOR MUCH OF THE UPCOMING WEEKEND. THE
NEXT MID/UPPER LEVEL SYSTEM IS THEN FORECAST TO PUSH INLAND TO
OUR NORTH SUNDAY INTO MONDAY...MAINLY ONLY IMPACTING THE PACIFIC
NORTHWEST AND NORTHERN CALIFORNIA. THUS...WILL MAINTAIN A DRY
FORECAST THROUGH THE EXTENDED.

&&

.AVIATION...AS OF 10:20 AM PDT TUESDAY...DEEP MARINE LAYER AROUND
THE BAY AREA WITH A MORE SUMMER LIKE PATTERN. MVFR CONDITIONS AT
ALL TERMINALS. BEGINNING TO THINK THIS MAY BE AN ALL DAY EVENT FOR
MANY LOCATIONS BASED ON LATEST GUIDANCE AND SATELLITE/OBS TRENDS.
THERE MAY BE A BRIEF PERIOD OF SOME SUN LATE THIS AFTERNOON...BUT
SHOULD BE AN EARLY RETURN WITH MVFR CONDITIONS AGAIN TONIGHT. CONF IS
MEDIUM.
 
VICINITY OF KSFO...CIGS WILL CONTINUE TO BE IN THE MVFR RANGE
AROUND THE BAY AREA. KSFO HAS SLOWLY BEEN TRENDING UPWARD AND WILL
CONTINUE THAT TREND ABOVE 1600 FEET BY 18Z. SQL AND PAO ARE
CURRENTLY AT 2K FEET. WINDS WILL REMAIN IN THE 240-250 DIRECTION
THROUGH EARLY THIS AFTERNOON SWITCH TO 280-290 THIS AFTERNOON WITH
SEA BREEZE. WINDS WILL INCREASE THIS AFTERNOON AS WELL.

SFO BRIDGE APPROACH...SIMILAR TO KSFO...CIGS WILL SLOWLY LIFT.
 
MONTEREY BAY AREA TERMINALS...MVFR CIGS THROUGH THE FORECAST. WILL
MAKE IT AN ALL DAY EVENT WITH NO CLEARING.

&&

.MARINE...AS OF 10:14 AM PDT TUESDAY...BUILDING HIGH PRESSURE OVER
THE EASTERN PACIFIC WILL RESULT IN MODERATE TO STRONG
NORTHWESTERLY WINDS TODAY. THE STRONGEST WINDS WILL BE MAINLY
NORTH OF POINT REYES WITH GALE FORCE WINDS OVER THE OUTER WATERS.
SEAS WILL RAPIDLY BUILD TODAY IN RESPONSE TO THESE WINDS. SHORT
PERIOD NORTHWESTERLY SWELLS ARE EXPECTED BY TONIGHT.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...PT ARENA TO PT REYES 10-60 NM UNTIL 3 PM
             GLW...PT ARENA TO PT REYES 10-60 NM FROM 3 PM
             SCA...PT REYES TO PIGEON PT 10-60 NM FROM 3 PM
             SCA...PT ARENA TO PT REYES 0-10 NM FROM NOON
             SCA...SF BAY NORTH OF THE BAY BRIDGE FROM 1 PM

&&

$$

PUBLIC FORECAST: BELL/RGASS
AVIATION/MARINE: MM

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




Return to Home page


Western Regional Climate Center, wrcc@dri.edu