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000
FXUS66 KMTR 161603
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
903 AM PDT SUN JUN 16 2013

.DISCUSSION...AS OF 9:00 AM PDT SUNDAY...THE MARINE LAYER
COMPRESSED OVERNIGHT...TO AROUND 1400 FEET...RESULTING IN LESS
LOW CLOUD COVERAGE INLAND THIS MORNING. PATCHY LOW CLOUDS WERE
MAINLY CONFINED TO THE COASTAL LOCATIONS...WITH MORE INLAND
INTRUSION THROUGH THE MONTEREY BAY AND SALINAS VALLEY.
TEMPERATURES OVERNIGHT WERE SIMILAR TO THOSE OBSERVED LAST
NIGHT...WITH READINGS IN THE MID 40S TO MID 50S.

LITTLE TO NO CHANGE IN THE UPPER LEVEL PATTERN IS EXPECTED BETWEEN
YESTERDAY AFTERNOON AND THIS AFTERNOON...WITH A BROAD UPPER TROUGH
IMPACTING THE NORTHERN AND CENTRAL CALIFORNIA COASTLINE. THIS WILL
KEEP THE REGION OF STRATUS NEARLY STAGNANT AND ALLOW FOR DECENT
ONSHORE FLOW AND NEARLY IDENTICAL DAYTIME HIGH TEMPERATURES TODAY
COMPARED TO YESTERDAY. TEMPERATURES ARE FORECAST TO WARM INTO THE
60S TO LOW 70S ALONG THE COAST...TO THE MID 70S TO MID 80S INLAND.
THE REGION SHOULD SEE STRONGER ONSHORE FLOW THIS AFTERNOON AS THE
SHORT TERM MODELS INDICATED THE SFO-SAC GRADIENT WILL PEAK JUST
OVER 5 MB...WHERE YESTERDAY AFTERNOON IT PEAKED AT 4.8 MB DURING
THE EARLY EVENING HOURS. STRONGER ONSHORE FLOW MAY ALSO RESULT IN
EARLY STRATUS RETURN...EVEN BY EARLY THIS EVENING FOR THE MONTEREY
AND SF BAYS.

OTHERWISE...CURRENT FORECAST LOOKS RIGHT ON TRACK WITH A DRY
WEATHER PATTERN AND LITTLE TEMPERATURES VARIATION THROUGH AT LEAST
THE END OF NEXT WEEK.

.PREVIOUS DISCUSSION...AS OF 3:36 AM PDT SUNDAY...TEMPERATURES
THIS MORNING GENERALLY IN THE 50S FOR MOST LOCATIONS WITH A FEW
SPOTS IN THE UPPER 40S. THE DEEP MARINE LAYER HAS MIXED
SLIGHTLY...YET REMAINS IN PLACE WITH LOW STRATUS OFFSHORE AND INTO
THE MONTEREY...SALINAS VALLEY AND SAN FRANCISCO BAY REGIONS.

VERY LITTLE HAS CHANGED IN THE PAST 24HRS ACROSS THE REGION WITH
UPPER LEVEL LOW PRESSURE REMAINING OFFSHORE...WEST OF THE WA/OR
COAST. THIS WILL KEEP ONSHORE FLOW AND THE PERSISTENT MARINE LAYER
ACROSS THE CENTRAL COAST THROUGH TUESDAY. THE UPPER LOW WILL
SLOWLY MOVE TOWARD THE PACIFIC NORTHWEST COAST BY MIDWEEK AND
BRINGING THE TROUGH AXIS THROUGH CENTRAL CALIFORNIA. AS A
RESULT...850MB TEMPERATURES COOL TUESDAY INTO WEDNESDAY AND WILL
BRING COOLER TEMPERATURES TO THE REGION. AS THE TROUGH PULLS
FURTHER EAST AWAY FROM THE WEST COAST...A RIDGE WILL BUILD BACK
OVERHEAD AND BRING A WARMING TREND FOR LATE NEXT WEEK INTO THE
WEEKEND.

&&

.AVIATION...AS OF 4:30 AM PDT SUNDAY...PROFILER DATA FROM BODEGA
BAY AND FORT ORD SHOW THE MARINE LAYER GETTING A LITTLE COMPRESSED
PRESENTLY DOWN TO 1400 FEET DEEP. LOW-MID LEVEL WARMING ACCOMPANIED
BY SLOWLY INCREASING 500 MB HEIGHTS (RIDGING) SUPPORTS A LOWER
MARINE LAYER DEPTH FOR THE DAYLIGHT HOURS AT LEAST. BY THE EVENING
A VERY WEAK SURFACE TO LOW LEVEL TROUGH WILL SLIDE SOUTHEAST ACROSS
THE NORTHERN COASTAL WATERS WHICH WILL VERY LIKELY LIFT THE MARINE
LAYER BACK UP AGAIN. ADDITIONALLY ANOTHER SURFACE TROUGH WILL SLIDE
ACROSS THE AREA MONDAY EVENING FURTHER DEEPENING (AND WEAKENING BY
LOW LEVEL COOLING) THE MARINE LAYER.

THE ONSHORE GRADIENT SFO-SAC IS FORECAST TO INCREASE TO 4-5 MB TODAY
AND AGAIN MONDAY. THIS WILL LEAD TO GUSTY WEST WINDS PARTICULARLY
ACROSS THE SAN FRANCISCO BAY WATERS.

VICINITY OF KSFO...LESS STRATUS WAS SEEN OVER THE COASTAL WATERS COMPARED
TO SATURDAY MORNING. LIGHT ONSHORE BREEZES AND A SLIGHTLY COMPRESSED MARINE
LAYER SUPPORT VFR THROUGH THE MORNING AND AFTERNOON. ONSHORE WINDS WILL
PICK UP THIS AFTERNOON AND IF STRATUS IS PLENTIFUL ON THE COAST AND
THE MARINE LAYER REVERSES TO DEEPENING AGAIN THEN EXPECT GREATER CHANCES
FOR AN EVENING RETURN.

KSFO BRIDGE APPROACH...MODERATE TO HIGH CONFIDENCE VFR. LOW CONFIDENCE
REGARDING TONIGHT AND MONDAY MORNING AS ONSHORE WINDS AND A DEEPER MARINE
LAYER COULD BRING STRATUS IN.

MONTEREY BAY AREA TERMINALS...IFR THROUGH THE MORNING. CLOUDS PERSISTED
ALL DAY YESTERDAY AS A DRY TROUGH PASSED THROUGH THE AREA. RIDGING TODAY
COULD HELP A LITTLE MORE AND MIX OUT THE STRATUS AT LEAST IN THE AFTERNOON
HOURS. AN EARLY RETURN IS LIKELY THIS EVENING.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
             SCA...PIGEON PT TO PT PIEDRAS BLANCAS 10-60 NM
             SCA...SF BAY FROM 1 PM

&&

$$

PUBLIC FORECAST: RILEY/RGASS
AVIATION/MARINE: CANEPA

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