Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 310431
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
930 PM PDT THU OCT 30 2014

.SYNOPSIS...
A TROUGH OF LOW PRESSURE DEEPENING ALONG THE WEST COAST FRIDAY WILL
BRING COOLER WEATHER AND A RAPIDLY DEEPENING MARINE LAYER. RAIN IS
LIKELY FRIDAY NIGHT INTO EARLY SATURDAY MORNING. THE RAIN WILL
CHANGE TO SHOWERS BY THE AFTERNOON. A FEW INCHES OF SNOW IS POSSIBLE
ABOVE 7000 FEET. COOL WEATHER WILL CONTINUE SUNDAY WITH ISOLATED
SHOWERS SHOWERS AT TIMES...MAINLY IN THE MOUNTAINS. WARMER DAYS
EARLY NEXT WEEK WITH WEAK TO MODERATE OFFSHORE FLOW AS HIGH PRESSURE
BUILDS OVER THE GREAT BASIN.

&&

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

MODELS ARE TRENDING A LITTLE STRONGER AND WETTER WITH THE POTENT
TROUGH THAT WILL IMPACT SOUTHERN CALIFORNIA FRIDAY NIGHT AND
SATURDAY. THE 18Z WRF PROJECTS BOUNDARY LAYER SATURATION TO 9000
FEET FRIDAY NIGHT. THIS IS 3000 FEET DEEPER THAN YESTERDAYS WRF. A
105KT 300 MB JET CORE WILL DIG THE TROUGH A LITTLE FARTHER SOUTH.
THERE IS ALSO A CONVECTIVE ELEMENT TO THE STORM WITH CAPE VALUES OF
200-400 J/KG OVER THE COASTAL WATERS AND ORANGE COUNTY BETWEEN
09-15Z SATURDAY. THIS IS WHEN THE SURFACE COLD FRONT MOVES INLAND
AND THE ADDED LIFT COULD FUEL BRIEFLY HIGHER RAIN RATES IN THE
CONVECTIVE CELLS. THERE IS ALSO A BRIEF SURGE OF HIGHER PRECIPITABLE
WATER OF 1.00" INTO SOCAL FRIDAY NIGHT. FACTOR IN OROGRAPHIC LIFT
FROM INCREASING SOUTHWEST 850 MB WINDS AND RAIN TOTALS OF AN INCH OR
MORE APPEAR REALISTIC OVER THE ORANGE COUNTY MOUNTAINS...THE SAN
BERNARDINO COUNTY MOUNTAINS...AND PERHAPS THE NORTHERN RIVERSIDE
COUNTY MOUNTAINS. THE PRECIP TOTALS OVER SAN DIEGO COUNTY FALL OFF
SLIGHTLY AS THE BEST UPPER LEVEL SUPPORT REMAINS NORTH OF THE AREA.
BUT THE SURFACE COLD FRONT...THE DEEP MOIST LAYER AND THE STRONG
OROGRAPHIC LIFT WILL STILL PRODUCE BENEFICIAL RAINS OF A HALF TO
THREE-QUARTERS OF AN INCH OVER THE MOUNTAINS. SO IT LOOKS LIKE WE
WILL BE TREATED WITH RAIN ON HALLOWEEN NIGHT.

THE TROUGH WILL BE SLOW TO EXIT THE AREA OVER THE WEEKEND AS A
SECOND STRONG SHORTWAVE ROUNDS THE BASE OF THE TROUGH SATURDAY
NIGHT. THIS WILL EVENTUALLY DEVELOP INTO A CLOSED LOW OVER SOCAL
SUNDAY MORNING. THIS SHORTWAVE WILL PROVIDE ENOUGH INSTABILITY TO
KEEP THE THREAT FOR SHOWERS THROUGH SUNDAY WITH THE BEST CHANCES IN
THE MOUNTAINS.

TEMPERATURES: COOLER FRIDAY WITH A SURGE OF MARINE AIR AND LOW
CLOUDS SPREADING INLAND. SATURDAY WILL BE EVEN COLDER WITH COASTAL
AND VALLEY HIGHS IN THE 60S. THE LAST TIME THE HIGH WAS IN THE 60S
AT LINDBERGH FIELD WAS MAY 24TH WHEN THE HIGH WAS 67.

WIND: STRONG SOUTHWEST WINDS AHEAD OF THE TROUGH ALONG WITH
INCREASING SURFACE PRESSURE GRADIENTS WILL GENERATE STRONG WINDS
OVER THE MOUNTAINS AND DESERTS. WEST TO SOUTHWEST WIND OF 30 TO 50
MPH WILL GUST AS HIGH AS 60 MPH IN THE WIND PRONE AREAS.

SNOW: SNOW LEVELS WILL BE AROUND 7000 FT WHEN PRECIPITATION BEGINS
LATE FRIDAY NIGHT...THEN LOWER TO AROUND 6000 FT BY LATE SATURDAY
MORNING. MOST OF THE HEAVY WET SNOW WILL MELT ON CONTACT BETWEEN
6000-6500 FEET...WITH SEVERAL INCHES OF ACCUMULATION ABOVE 7000
FEET.

EARLY NEXT WEEK WE ARE LOOKING AT A DRY WEATHER PATTERN AND A PERIOD
OF WEAK TO MODERATE OFFSHORE WINDS AS SURFACE HIGH PRESSURE BUILDS
OVER THE GREAT BASIN. TEMPERATURES WILL SLOWLY INCREASE EACH DAY
THROUGH THURSDAY WITH GUSTY OFFSHORE WINDS AT TIMES IN THE MOUNTAIN
PASSES.

&&

.AVIATION...
310237Z...BKN-SCT CLOUDS AOA 13000 FT MSL OVER THE AREA WILL BECOME
FEW-SCT BY 1200 UTC. LOW CLOUDS ARE EXPECTED TO EVENTUALLY FILL IN
15-25 SM INLAND THROUGH 1200 UTC...WITH OVC-BKN BASES OF 1300-1700
FT MSL AND TOPS AROUND 2000-2500 FT MSL. 1200-1800 UTC...LOW CLOUDS
WILL LIKELY MAKE IT 35-45 SM INLAND AND DEEPEN...WITH BASES BECOMING
2000-3000 FT MSL AND TOPS RISING TO 3500-4500 FT MSL. EXPECTING ONLY
PARTIAL CLEARING OF LOW CLOUDS 1500-01/0000 UTC...WITH BKN-SCT CIGS
PROBABLY CONTINUING AT KSAN...KCRQ AND KSNA. 01/0000-1200
UTC...MULTIPLE BKN-OVC CLOUD LAYERS DEVELOPING IN THE 2000-10000 FT
MSL LAYER OVER AND WEST OF THE MOUNTAINS...WITH EMBEDDED SHOWERS
GRADUALLY INCREASING IN COVERAGE AND INTENSITY...MTN OBSCURATION OF
COASTAL SLOPES...AREAS OF CIGS 1000-500 FT AGL AND AREAS OF VIS AOB
5 SM DUE TO SHOWERS/MIST.

W TO SW WINDS 20-30 KT GUSTING TO 40-55 KT OVER MOUNTAIN
RIDGES...THROUGH PASSES/CANYONS...ALONG DESERT SLOPES AND INTO
ADJACENT DESERT AREAS WILL RESULT IN MOD-STG UP/DOWNDRAFTS...LLWS
AND POSSIBLE ROTORS OVER AND E OR NE OF THE MOUNTAINS STARTING 2100
UTC. DESERTS SHOULD CONTINUE TO HAVE UNRESTRICTED VIS THROUGH
01/1200 UTC...EXCEPT FOR LOCAL VIS AOB 5SM IN BLOWING DUST/SAND
AFTER 2100 UTC. ANY SHOWERS NOT EXPECTED TO IMPACT THE DESERTS UNTIL
AFTER 01/0900 UTC.

&&

.MARINE...
737 PM...NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH FRIDAY. A
TROUGH OF LOW PRESSURE AND ASSOCIATED COLD FRONT MOVING THROUGH
SOUTHERN CALIFORNIA WILL BRING WEST TO NORTHWEST WINDS GUSTING TO
25-30 KT AND STEEP WAVES TO THE SAN DIEGO COUNTY COASTAL WATERS
SATURDAY. A SMALL CRAFT ADVISORY WILL BE IN EFFECT FROM EARLY
SATURDAY MORNING THROUGH LATE SATURDAY NIGHT...SEE LAXMWWSGX FOR
DETAILS. CONDITIONS WILL IMPROVE DURING THE DAY SUNDAY.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...WIND ADVISORY FROM 8 PM FRIDAY TO 5 PM PDT SATURDAY FOR THE
     APPLE AND LUCERNE VALLEYS...COACHELLA VALLEY...RIVERSIDE
     COUNTY MOUNTAINS...SAN BERNARDINO COUNTY MOUNTAINS...SAN
     DIEGO COUNTY DESERTS...SAN DIEGO COUNTY MOUNTAINS.

     WINTER WEATHER ADVISORY FROM 11 PM FRIDAY TO 2 PM PDT SATURDAY
     ABOVE 6500 FEET FOR THE RIVERSIDE COUNTY MOUNTAINS...SAN
     BERNARDINO COUNTY MOUNTAINS.

     FLASH FLOOD WATCH FROM FRIDAY EVENING THROUGH SATURDAY
     MORNING FOR THE SANTA ANA MOUNTAINS AND FOOTHILLS.

PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 5 AM PDT SATURDAY TO 4 AM
     PST SUNDAY FOR THE COASTAL WATERS FROM SAN MATEO POINT TO
     THE MEXICAN BORDER AND OUT 30 NM...WATERS FROM SAN MATEO
     POINT TO THE MEXICAN BORDER EXTENDING 30 TO 60 NM OUT
     INCLUDING SAN CLEMENTE ISLAND.


&&

$$

PUBLIC...MOEDE
AVIATION/MARINE...HARRISON







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