Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 212138
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
138 PM PST FRI NOV 21 2014

.SYNOPSIS...
PARTLY CLOUDY SKIES AND COOL CONDITIONS WILL CONTINUE FOR THE REST
OF THE DAY AND INTO SATURDAY WITH NORTHWEST FLOW ALOFT. STRONGER
ONSHORE FLOW WILL BRING STRONG AND GUSTY WEST WINDS IN THE MOUNTAINS
AND DESERTS...PARTICULARLY SATURDAY NIGHT INTO SUNDAY MORNING. DRY
AND WARMER WITH MOSTLY CLEAR SKIES SUNDAY THROUGH THURSDAY AS HIGH
PRESSURE BUILDS ALOFT AND SURFACE OFFSHORE FLOW DEVELOPS. WINDS MAY
BE LOCALLY STRONG AND GUSTY IN THE MORE WIND PRONE AREAS AT TIMES.

&&

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

VISIBLE SATELLITE SHOWS SOME LEFT-OVER CUMULUS CLOUDS OVER THE
MOUNTAINS AND VALLEYS THIS AFTERNOON...AND OBSERVATIONS SHOW
TEMPERATURES MOSTLY AT LEAST A FEW DEGREES LOWER THAN 24 HOURS AGO.
EARLIER THIS MORNING...A POTENT VORT MAX INDICATED BY WATER VAPOR
IMAGERY MOVING AROUND THE BASE OF THE TROUGH SPARKED HEAVIER SHOWERS
AND THUNDERSTORMS. DUE TO THE SHOWERY NATURE OF THE
PRECIPITATION...MANY SPOTS RECEIVED ONLY A FEW HUNDREDTHS OF AN
INCH...SUCH AS LINDBERGH FIELD...WHILE OTHER SPOTS RECEIVED 0.30 TO
0.50 INCHES...WITH SOME COASTAL MOUNTAIN LOCATIONS HAVING GOTTEN
OVER 1.25 INCHES. EVEN THE COACHELLA VALLEY AND SAN DIEGO COUNTY
DESERTS GOT SOME LIGHT AMOUNTS. MEANWHILE...NORTHWEST ORANGE
COUNTY...THE HIGH DESERTS AND SOUTHERN INLAND EMPIRE RECEIVED ALMOST
NO RAINFALL AT ALL. WE ALSO HAD A FEW REPORTS OF 2-3 INCHES OF SNOW
ON THE HIGHER PEAKS...WITH A SNOW LEVEL DOWN TO 6000-6500 FEET.

SOME UPPER LEVEL RIDGING WILL REPLACE THE DEPARTING TROUGH ON
SATURDAY...BRINGING SLIGHT WARMING TO THE AREA...ALTHOUGH DAY-TIME
HIGHS WILL STILL BE BELOW NORMAL EXCEPT NEAR TO SLIGHTLY ABOVE
NORMAL IN THE DESERTS. A SHORT-WAVE TROUGH MOVING THROUGH THE GREAT
BASIN LATE SATURDAY INTO SUNDAY MORNING WILL KEEP THE MARINE LAYER
FAIRLY DEEP...WITH NIGHT AND MORNING CLOUDS DEVELOPING INTO THE
COAST AND VALLEY SECTIONS AND ALONG THE COASTAL SLOPES. THE ONSHORE
PRESSURE GRADIENT WILL TIGHTEN AS THE SHORT-WAVE PASSES BY...AND
PRODUCE SOME GUSTY WEST WINDS IN THE MOUNTAINS AND DESERTS...WITH
40-50 MPH AND LOCAL 55 MPH GUSTS POSSIBLE. A WIND ADVISORY HAS BEEN
ISSUED FOR THE MOUNTAINS AND DESERTS.

ON SUNDAY...SURFACE HIGH PRESSURE BUILDING OVER THE GREAT BASIN IN
THE WAKE OF THE AFOREMENTIONED SHORT-WAVE WILL BRING OFFSHORE
PRESSURE GRADIENTS TO SOUTHERN CALIFORNIA...RESULTING IN A RETURN OF
SANTA ANA WINDS. OFFSHORE PRESSURE GRADIENTS OF 9-10 MB FROM SAN
DIEGO TO TONOPAH ARE FORECAST BY THE MODELS ON SUNDAY...WITH THE
NAM12 SHOWING DECENT UPPER LEVEL SUPPORT WITH 850 MB WINDS OF 40-45
KT. HIGH-RES MODELS SHOW THE POTENTIAL FOR 40-50 MPH GUSTS THROUGH
AND BELOW THE CAJON PASS...SAN GORGONIO PASS AND INTO THE SANTA
MOUNTAINS AND FOOTHILLS THAT DAY. THE OFFSHORE FLOW WILL ALSO
ERADICATE THE MARINE LAYER...MAKING FOR MOSTLY CLEAR SKIES. UPPER
LEVEL SUPPORT WEAKENS ON MONDAY...WITH MOSTLY WEAK TO LOCALLY
MODERATE OFFSHORE FLOW OCCURRING...ALTHOUGH SINCE THE GRADIENT
SHIFTS MORE TO THE NORTHEAST...THE SAN DIEGO COUNTY MOUNTAINS ARE
LIKELY TO SEE STRONGER WINDS THAT DAY THAN ON SUNDAY. THEN ON
TUESDAY...THE SURFACE HIGH SHIFTS FARTHER EAST INTO COLORADO...WITH
THE OFFSHORE GRADIENT STRENGTHENING BUT STILL WEAK UPPER LEVEL
SUPPORT. THE BETTER EASTERLY GRADIENT SHOULD FAVOR THE
NORTH-TO-SOUTH ORIENTED MOUNTAINS...PASSES AND CANYONS OF SAN DIEGO
COUNTY AND RIVERSIDE COUNTY ON TUESDAY...WITH THE POTENTIAL FOR
LOCAL GUSTS OF 35-45 MPH. THE OFFSHORE WINDS MAY BE WEAKER ON
WEDNESDAY...WITH CONTINUED WEAKENING OF WINDS ON THURSDAY. THE
MARINE LAYER WILL CONTINUE TO BE A NON-FACTOR UNTIL POSSIBLY
THURSDAY NIGHT WHEN THE FLOW STARTS TO TURN ONSHORE. THE OFFSHORE
FLOW AND AN UPPER LEVEL RIDGE BUILDING OVER THE REGION WILL ALSO
BRING GRADUAL WARMING...WITH DAY-TIME HIGHS REACHING 5-15 DEGREES
ABOVE NORMAL BY WEDNESDAY.

&&

.AVIATION...
212100Z...COASTS/VALLEYS/MTNS...SCT TO LOCALLY BKN CLOUD LAYERS THIS
AFTERNOON WITH BASES GENERALLY AOA 3500 FT MSL. GRADUAL CLEARING
AFTER 22/00Z. NO STRATUS EXPECTED OVERNIGHT. MOSTLY CLEAR WITH
UNRESTRICTED VIS THROUGH SATURDAY AFTERNOON.

DESERTS...MOSTLY CLEAR WITH UNRESTRICTED VISIBILITY THROUGH SATURDAY.

&&

.MARINE...
100 PM...WINDS OVER THE OUTER COASTAL WATERS HAVE DECREASED.
THEREFORE THE SMALL CRAFT ADVISORY WILL BE CANCELED. BREEZY
WEST-NORTHWEST WINDS AROUND 20-25 KNOTS ARE POSSIBLE AGAIN SATURDAY
EVENING THROUGH SUNDAY MORNING AS ANOTHER TROUGH MOVES ACROSS THE
REGION. NO HAZARDOUS MARINE WEATHER IS EXPECTED SUNDAY AFTERNOON
THROUGH TUESDAY.

&&

.FIRE WEATHER...
DRY OFFSHORE FLOW DEVELOPING SUNDAY WITH GUSTY NORTHEAST WINDS
SURFACING IN THE MOUNTAINS AND THROUGH THE PASSES AND CANYONS INTO
THE INLAND VALLEYS. THE STRONGEST WINDS WILL INITIALLY SURFACE FROM
CAJON SUMMIT THROUGH THE CAJON PASS AND INTO THE INLAND EMPIRE AND
ORANGE COUNTY SUNDAY MORNING. WINDS IN THESE AREAS WILL RANGE FROM
20-30 MPH WITH PEAK GUSTS TO 45-50 MPH AT THE MOST WIND PRONE
LOCATIONS. THE GUSTY WINDS WILL SPREAD INTO THE SAN JACINTO AND SAN
DIEGO COUNTY MOUNTAINS MIDDAY SUNDAY. WIND GUSTS IN THESE AREAS WILL
BE NOT QUITE AS STRONG WITH 15-25 MPH WINDS WITH GUSTS OF 40-45 MPH.

MAX TEMPERATURES SUNDAY WILL BE IN THE UPPER 60S AND LOWER 70S IN
THE VALLEYS WITH MINIMUM HUMIDITIES FALLING TO 15-25 PERCENT SUNDAY
AFTERNOON. COOLER IN THE MOUNTAINS AND FOOTHILLS WITH HIGHS IN THE
50S TO MID 60S. RECENT RAINS HAVE BRIEFLY INCREASED FUEL MOISTURE
WHICH WILL ALLEVIATE THE FIRE WEATHER POTENTIAL SUNDAY.

MONDAY THROUGH THURSDAY...WEAK TO OCCASIONALLY MODERATE OFFSHORE
WINDS WILL CONTINUE THROUGH THURSDAY WITH PROGRESSIVELY WARMER DAYS
AND LOWER DAYTIME HUMIDITIES FROM 8 TO 15 PERCENT. THE FIRE WEATHER
CONCERNS WILL BE ELEVATED NEXT WEEK AND THE POTENTIAL FOR RED FLAG
CONDITIONS WILL BE EVALUATED OVER THE WEEKEND.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...WIND ADVISORY FROM 7 PM SATURDAY TO 4 AM PST SUNDAY FOR THE
     COACHELLA VALLEY...RIVERSIDE COUNTY MOUNTAINS...SAN DIEGO
     COUNTY DESERTS...SAN DIEGO COUNTY MOUNTAINS.

     WIND ADVISORY FROM 1 PM SATURDAY TO 4 AM PST SUNDAY FOR THE
     APPLE AND LUCERNE VALLEYS...SAN BERNARDINO COUNTY MOUNTAINS.

PZ...NONE.

&&

$$

PUBLIC...HARRISON
AVIATION/MARINE...TS
FIRE WEATHER...MOEDE




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