Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 180018 AAB
AFDSGX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SAN DIEGO CA
520 PM PDT WED SEP 17 2014

UPDATED FOR CANCELLATION OF THE FLASH FLOOD WATCH

.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL MOVE INTO THE REGION THURSDAY THROUGH THE
WEEKEND WHICH WILL BRING A DRYING AND COOLING TREND AND A RETURN OF
THE MARINE LAYER...WITH PATCHY COASTAL AND VALLEY LOW CLOUDS DURING
THE NIGHTS AND MORNINGS. THE MARINE LAYER MAY BECOME DEEP ENOUGH TO
BRING PATCHY DRIZZLE TO THE COAST AND VALLEYS THURSDAY NIGHT THROUGH
FRIDAY MORNING. STRONGER ONSHORE FLOW WILL BRING GUSTY WEST WINDS IN
THE MOUNTAINS AND DESERTS THURSDAY EVENING THROUGH FRIDAY MORNING.
HIGHER PRESSURE ALOFT WILL RE-DEVELOP EARLY NEXT WEEK...BRINGING
WARMER WEATHER.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

WATER VAPOR IMAGERY SHOWS CONVECTION ASSOCIATED WITH TROPICAL STORM
ODILE MOVING OVER SONORA TO THE EAST-NORTHEAST AND A TROUGH OFF THE
NORTHERN CALIFORNIA COAST. THIS TROUGH WILL SLOWLY APPROACH THE WEST
COAST TODAY INTO TOMORROW...WITH A CLOSED LOW SPLITTING OUT OF THE
TROUGH AND MOVING INTO A POSITION NEAR POINT CONCEPTION BY SATURDAY
AND THEN MOVING OFF TO THE NORTHEAST SUNDAY. LOCAL WRF INDICATES A
RETURN OF THE MARINE LAYER TONIGHT AS ONSHORE FLOW AND WESTERLY FLOW
ALOFT KICKS IN. THIS SHOULD BRING SOME PATCHY LOW CLOUDS INTO THE
COAST AND VALLEY SECTIONS TONIGHT INTO TOMORROW MORNING. THE TROUGH
WILL ALSO COOL THINGS DOWN SIGNIFICANTLY TOMORROW AND MORE-SO ON
FRIDAY...WITH DAY-TIME HIGHS A FEW DEGREES BELOW NORMAL ON FRIDAY.
THE TROUGH WILL ALSO GENERATE SOME STRONGER ONSHORE PRESSURE
GRADIENTS...RESULTING IN GUSTY WEST WINDS IN THE MOUNTAINS AND
DESERTS THURSDAY EVENING THROUGH FRIDAY MORNING...WITH GUSTS OF
40-45 MPH LIKELY...AND ISOLATED 50 MPH GUSTS. WITH THE DEEPENING
TROUGH OVER THE AREA...THE MARINE LAYER LOOKS TO DEEPEN AS
WELL...WITH NIGHT AND MORNING CLOUDS MOVING DEEP INTO THE VALLEYS
THURSDAY NIGHT THROUGH AT LEAST SATURDAY MORNING. IN FACT...IT MAY
BECOME THICK AND DEEP ENOUGH THURSDAY NIGHT THROUGH FRIDAY MORNING
TO PRODUCE SOME DRIZZLE...AND A FEW OF THE MODELS SHOW SOME SPOTTY
LIGHT PRECIP ACCUMULATIONS WITHIN THE MARINE LAYER FOR THAT TIME.

AS THE LOW MEANDERS NEAR POINT CONCEPTION SATURDAY INTO EARLY
SUNDAY...MODELS INDICATE MOISTURE GETTING PULLED UP FROM THE SOUTH
EAST OF THE AREA...WHICH MEANS THAT WE WILL PROBABLY STAY DRY.
HOWEVER...IF ENOUGH MOISTURE SNEAKS WEST INTO OUR FORECAST
AREA...THEN THE DYNAMICS PROVIDED BY THE LOW COULD BRING SOME
PRECIPITATION TO SOUTHERN CALIFORNIA. THE FORECAST REMAINS DRY FOR
NOW. TEMPERATURES WILL LIKELY BE SIMILAR TO FRIDAY THIS WEEKEND.

FOR MONDAY THROUGH TUESDAY...A WEST-TO-EAST ORIENTED RIDGE MAY BUILD
OVER THE AREA...WHICH WOULD BRING WARMING AND A MUCH SHALLOWER
MARINE LAYER.

&&

.AVIATION...
172000Z...COAST...MAINLY CLEAR WITH VISIBILITIES UNRESTRICTED
THROUGH 18/13Z. AFTER 18/13Z SCT-BKN STRATUS BASED AROUND 1200 FEET
MSL WITH TOPS TO NEAR 1800 FEET MSL. STRATUS SHOULD REACH INLAND TO
ABOUT KNKX-KSEE AND REMAIN WELL TO THE WEST OF KONT. VISIBILITY WILL
LOWER TO AROUND 1-3 SM IN HAZE AND FOG WHERE LOW CLOUDS INTERSECT
HIGHER TERRAIN. CONFIDENCE IN THE STRATUS DEVELOPING ALONG THE COAST
TONIGHT IS LOW-MODERATE.

VALLEYS/MOUNTAINS/DESERTS...MOSTLY CLEAR WITH UNRESTRICTED
VISIBILITIES...EXCEPT SCATTERED +SHRA AND +TSRA WILL
DEVELOP...MAINLY FAR EASTERN VALLEYS...MOUNTAINS...AND DESERTS...
THROUGH THIS EVENING. CLOUD BASES WILL BE AROUND 6000 FT MSL...WITH
CB TOPS TO 35000 FT MSL. STRONG UP/DOWNDRAFTS...GUSTY SURFACE
WINDS...LIGHTENING...SMALL HAIL...AND REDUCED VISIBILITY DUE TO +RA
WILL BE POSSIBLE NEAR STORMS.

&&

.MARINE...
300 PM...BREEZY WEST TO NORTHWEST WIND GUSTS TO 25 KT WILL CONTINUE
NEAR IN THE OUTER WATERS NEAR SAN CLEMENTE ISLAND THROUGH EARLY THIS
EVENING AS ONSHORE FLOW DEVELOPS. THERE WILL BE SLIGHTLY WEAKER
WINDS THURSDAY...BUT SOME GUSTS TO 20 KT ARE STILL POSSIBLE OVER THE
OUTER COASTAL WATERS THURSDAY AFTERNOON. OTHERWISE...NO HAZARDOUS
MARINE WEATHER IS EXPECTED THROUGH SUNDAY.

&&

.BEACHES...
AT 1 PM...A LONG PERIOD SOUTHERLY SWELL WILL CONTINUE TO PRODUCE
STRONG RIP AND LONGSHORE CURRENTS...AS WELL AS ELEVATED
SURF...THROUGH THURSDAY. SURF OF 4 TO 6 FEET WITH LOCALLY HIGHER
SETS WILL CONTINUE ON EXPOSED SOUTHWEST FACING BEACHES. THE SWELL
WILL SLOWLY LOWER FRIDAY INTO THE WEEKEND...DIMINISHING THE SURF AND
RIP CURRENT THREAT. A BEACH HAZARDS STATEMENT FOR ELEVATED SURF AND
STRONG RIP AND LONGSHORE CURRENTS REMAINS IN EFFECT THROUGH THURSDAY
EVENING.

&&

.SKYWARN...
SKYWARN ACTIVATION WILL NOT BE NEEDED THURSDAY.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...BEACH HAZARDS STATEMENT THROUGH THURSDAY EVENING FOR THE
     BEACHES IN THE ORANGE COUNTY COASTAL AREAS...SAN DIEGO COUNTY
     COASTAL AREAS.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 9 PM PDT THIS EVENING FOR
     THE WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER
     EXTENDING 30 TO 60 NM OUT INCLUDING SAN CLEMENTE ISLAND.

&&

$$

PUBLIC...HARRISON/MOEDE
AVIATION/MARINE/BEACHES...JJT/SMALL/MAXWELL











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