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000
FXUS66 KSGX 090518
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
918 PM PST SUN DEC 8 2013

.SYNOPSIS...
BUILDING HIGH PRESSURE OVER THE GREAT BASIN WILL FORCE STRONG
NORTHEAST WIND GUSTS THROUGH AND BELOW WIND PRONE PASSES AND CANYONS
ON MONDAY. STRONGEST WINDS WILL OCCUR BELOW THE CAJON PASS AND THE
SANTA ANA MOUNTAIN CANYONS...WEAKENING ON TUESDAY. THE GUSTY
WINDS WILL USHER IN VERY DRY AND COLD AIR...HOLDING DAYTIME HIGHS
WELL BELOW NORMAL AGAIN ON MONDAY. TEMPERATURES WILL MODERATE INTO
THE WEEKEND AS HIGH PRESSURE OVER THE EAST PACIFIC DRIFTS EAST OVER
THE REGION.

&&

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

IR SATELLITE IMAGERY SHOWED A THIN BAND OF HIGH CLOUDS DRIFTING SE
ACROSS SOCAL THIS EVENING. SOME LOWER CLOUDS WERE EVIDENT AS WELL
OFFSHORE AND OVER PORTIONS OF THE INLAND EMPIRE. TEMPERATURES WERE
RUNNING SEVERAL DEGREES LOWER THAN LAST EVENING...AND DEWPOINTS WERE
SOME 5 TO 15 DEGREES LOWER AS WELL. THE 00Z MIRAMAR SOUNDING STILL
HAD A MOIST LAYER BELOW 4500 FEET TOPPED BY A WEAK INVERSION. AT 04Z
SURFACE PRESSURE GRADIENTS WERE SHOWING STRONG OFFSHORE TRENDS FROM
NV BUT WERE STILL NEUTRAL TO THE LOWER DESERTS. WINDS WERE MOSTLY
LIGHT AT 8 PM PST...BUT A FEW SITES WERE BEGINNIG TO PICK UP FROM
THE NE.

AREAS OF CLOUDS NEAR THE INVERSION LEVEL MAY LINGER FOR A FEW MORE
HOURS BEFORE DECREASING LATER TONIGHT AS FLOW BECOMES INCREASINGLY
OFFSHORE. IF THE SKIES REMAIN CLEAR LONG ENOUGH AND WINDS ARE
LIGHT...SOME PATCHY FROST IS LIKLEY BY MORNING IN THE VALLEYS AND
LOWER DESERTS. A FROST ADVISORY HAS BEEN POSTED. EXPECT ANOTHER COOL
DAY ON MON...BUT SKIES SHOULD BE CLEAR WITH FULL SUN. GUSTY NE WINDS
WILL PREVAIL NEAR THE FOOTHILLS ADDING TO THE CHILL.

A STRONG...AMPLIFIED HIGH PRESSURE RIDGE OVER THE EASTPAC AND A DEEP
COLD TROUGH OVER THE INTERIOR OF N.A. CONTINUE A CHILLY NORTH FLOW
OVER SOCAL. A WEAK TROUGH EMBEDDED IN THAT FLOW IS PASSING THROUGH
THE REGION TONIGHT...ACCOMPANIED BY THIN HIGH CLOUDS. IN THE WAKE OF
THE TROUGH...A SURFACE HIGH IS EXPECTED TO STRENGTHEN TO AROUND 1042
MBS OVER NV. THIS WILL SET UP A STRONG OFFSHORE SURFACE GRADIENT ON
MON. THE WINDS WILL BE SUPPORTED BY A SHARP THICKNESS GRADIENT AND
MODERATE NW FLOW ALOFT. AREAS BELOW THE CAJON PASS AND THROUGH THE
SANTA ANA CANYONS WILL BE FAVORED FOR THE STRONGEST WIND GUSTS TO
AROUND 60 MPH OR MORE BEGINNING MON MORNING...PEAKING DURING THE DAY
INTO THE EVENING...THEN GRADUALLY SUBSIDING INTO TUE.

THE DRY...COOL AIR AND MOSTLY CLEAR SKIES WILL SET THE STAGE FOR
FROSTY CONDITIONS BECOMING MORE WIDESPREAD IN AREAS WHERE THE WIND
DOES NOT SURFACE. ADVISORIES HAVE BEEN POSTED FOR THE FROST
THROUGHOUT THE VALLEYS AND DESERTS TONIGHT. HOWEVER...THE COLDEST
NIGHT LOOKS TO BE MON NIGHT. ANOTHER FROST ADVISORY WILL LIKELY BE
ISSUED THEN.

AFTER TUE MORNING...RISING HEIGHTS/THICKNESS ACROSS THE REGION WILL
RESULT IN WARMER WEATHER. THE AMPLIFIED RIDGE OFF THE COAST IS
FORECAST TO WEAKEN AND SLIDE EAST TUE THROUGH THU. A LESS AMPLIFIED
WESTERLY FLOW IS FORECAST TO DEVELOP INTO N.A. THROUGH EARLY NEXT
WEEK SO TEMPS SHOULD BE NEAR SEASONAL NORMALS WITH NO SIGNIFICANT
PRECIP IN SIGHT.

&&

.AVIATION...
090415Z...COAST/VALLEYS/MTNS...SCT-BKN LAYERS 4000-6000 FT MSL
OBSCURING HIGHER TERRAIN AT TIMES THROUGH TONIGHT. MOSTLY CLEAR WITH
UNRESTRICTED VSBY ON MONDAY.

AREAS OF N TO NE WINDS 20-25 KTS GUSTING TO 40 KTS DEVELOPING AFTER
12Z. LOCAL SFC GUSTS TO 55 KTS POSSIBLE 15-00Z BELOW THE FAVORED
PASSES AND CANYONS. THIS WILL RESULT IN STG-SVR UDDFS AND AREAS OF
LLWS OVER THE MOUNTAINS AND ADJACENT COASTAL FOOTHILLS.

DESERTS...SCT-BKN CLOUDS WITH BASES 6000-7000 FT MSL GRADUALLY
CLEARING IN THE COACHELLA VALLEY TONIGHT. OTHERWISE SCT CLOUDS
AOA 20000 FT MSL AND UNRESTRICTED VSBY THROUGH MONDAY.

&&

.FIRE WEATHER...
SEVERAL HOURS OF CRITICAL OR NEAR CRITICAL FIRE WEATHER CONDITIONS
ARE LIKELY ON MONDAY AS STRONG NORTHEAST WINDS SURFACE BELOW THE
CAJON PASS...BANNING PASS...ALONG AND NORTH OF THE I-10 IN THE
COACHELLA VALLEY...THROUGH AND BELOW THE SANTA ANA MTN CANYONS...AND
ALONG THE COASTAL FOOTHILLS AND WIND PRONE CANYONS BELOW THE SAN
DIEGO COUNTY MTNS. SURFACE NORTHEAST WINDS OF 25 MPH WITH GUSTS OVER
35 MPH...AND RH OF 10-15 PERCENT FOR SEVERAL HOURS ARE EXPECTED
DURING THE DAY. THESE CONDITIONS WILL SUBSIDE SLIGHTLY OVERNIGHT...
THEN RETURN ON TUE...BUT BE MORE LIMITED IN EXTENT AND DURATION.

RECENT RAINS IN SOME AREAS...AND TEMPERATURES IN THE 50S MAY HELP TO
LIMIT THE WILDFIRE THREAT.

&&

SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING FROM LATE TONIGHT THROUGH TUESDAY MORNING FOR
THE ORANGE COUNTY COASTAL AREAS...SAN BERNARDINO COUNTY
MOUNTAINS...SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE
INLAND EMPIRE...SANTA ANA MOUNTAINS AND FOOTHILLS.

WIND ADVISORY FROM LATE TONIGHT THROUGH TUESDAY MORNING FOR THE
SAN DIEGO COUNTY VALLEYS...RIVERSIDE COUNTY MOUNTAINS...SAN
DIEGO COUNTY MOUNTAINS...COACHELLA VALLEY.

FROST ADVISORY FROM 10 PM THIS EVENING TO 9 AM PST MONDAY FOR
THE COACHELLA VALLEY...SAN BERNARDINO AND RIVERSIDE COUNTY
VALLEYS-THE INLAND EMPIRE...SAN DIEGO COUNTY DESERTS...SAN
DIEGO COUNTY VALLEYS.

&&

$$

PUBLIC...JAD
AVIATION/MARINE...SS