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000
FXUS66 KSGX 121736
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
935 AM PST THU DEC 12 2013

.SYNOPSIS...
UPPER LEVEL LOW WILL GRADUALLY MOVE EAST TODAY...WITH A FEW WRAP
AROUND SHOWERS BRINGING LIGHT RAIN TO THE DESERTS AND MOUNTAINS
THROUGH THIS MORNING.  AN INSIDE SLIDER WILL THEN DIVE ACROSS THE
REGION ON FRIDAY...CONTINUING THE COOLER WEATHER.  HOWEVER...DRY AND
WARMER CONDITIONS WILL DEVELOP FOR THE WEEKEND AND EARLY NEXT
WEEK...AS HIGH PRESSURE REBUILDS OVER CALIFORNIA.  MODERATE TO
STRONG AND GUSTY NORTHEAST AND EAST WINDS WILL ALSO DEVELOP SATURDAY
MORNING AND CONTINUE THROUGH SUNDAY...WITH WEAKER...BUT STILL
LOCALLY MODERATE OFFSHORE WINDS CONTINUING INTO THE WORK WEEK.

&&

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

WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL LOW MOVING INLAND ACROSS
SOUTHERN CALIFORNIA THIS MORNING...BRINGING SCATTERED SHOWERS AND
THUNDERSTORMS TO THE SOUTHEASTERN DESERTS OF CALIFORNIA.  COMPOSITE
RADAR IMAGERY SHOWS THESE SHOWERS WEAKENING AS THEY WRAP AROUND INTO
THE COACHELLA VALLEY AND SAN DIEGO COUNTY DESERTS.  ALTHOUGH THE
ATMOSPHERE IS VERY DRY BELOW 700 MBS...SOME LIGHT RAIN IS REACHING
THE SURFACE...WITH A COUPLE OF GAGES REPORTING A HUNDREDTH OR TWO.
THERMAL IS ONE OF THESE LOCATIONS...REPORTING LIGHT RAIN ON THEIR 9
AM OBSERVATION...AND A SPOTTER REPORT SOME PEA SIZE HAIL NEAR
PIONEERTOWN.  FOR THE MOST PART THOUGH...PRECIPITATION TOTALS WILL
BE EXTREMELY LIGHT...AT LESS THAN A TENTH OF AN INCH.  AS THIS LOW
SLOWLY SHIFTS EAST THOUGH...THE SHOWERS WILL TAPER OFF...WITH
TEMPERATURES REMAINING WITHIN TO SLIGHTLY BELOW NORMAL FOR THIS TIME
OF YEAR.

WATER VAPOR IMAGERY ALSO SHOWS A TROUGH ALONG 130 WEST THIS
MORNING...WHICH WILL THEN DIVE ACROSS CALIFORNIA AND INTO THE DESERT
SOUTHWEST ON FRIDAY.  THE MODELS ARE SHOWING THE MARINE LAYER
REDEVELOPING TONIGHT...AHEAD OF THIS NEXT SYSTEM...BUT THINK IT
MIGHT BE A LITTLE SLOWER TO RETURN THAN THE CURRENT MODELS ARE
SHOWING.  OTHERWISE...EXPECT SLIGHTLY COOLER CONDITIONS TO PREVAIL
THROUGH FRIDAY...WITH LOCALLY GUSTY ONSHORE WINDS DEVELOPING ACROSS
THE MOUNTAINS AND DESERTS.

THE MAIN CONCERN FOR THIS FORECAST PERIOD THOUGH WILL BE WITH THE
DEVELOPING OFFSHORE WIND EVENT FOR THIS WEEKEND AND EARLY NEXT
WEEK...AS HIGH PRESSURE REBUILDS OVER THE REGION.  THE 12Z MODELS
ARE STARTING TO TREND STRONGER WITH THIS UPCOMING WIND EVENT...WITH
THE SAN DIEGO TO TONOPAH GRADIENT PEAKING BETWEEN 15 AND 16 MBS ON
SATURDAY MORNING.  UPPER LEVEL WIND SUPPORT VARIES BETWEEN THE
MODELS...BUT THE 12Z NAM SHOWS 30 TO 35 KTS...WHILE THE 06Z WRF
SHOWS 45 TO 55 KTS.  OUR IN HOUSE GUIDANCE IS ALSO CONSISTENTLY
SHOWING GUSTS TO AROUND 50 MPH...WITH SOME LOCAL GUSTS PUSHING 60
MPH IN THE FAVORED AREAS OF SAN BERNARDINO AND ORANGE COUNTIES.
THEREFORE...MAY NEED TO CONSIDER A HIGH WIND WATCH WITH THE
AFTERNOON PACKAGE...BUT WANT TO WAIT TO SEE HOW THE CANSAC AND THE
ECMWF TRENDS BEFORE MAKING THAT DECISION.  NEEDLESS TO DAY...IT WILL
LIKELY BE BREEZY TO WINDY ACROSS THE REGION.  THESE NORTHEAST WINDS
WILL GRADUALLY TRANSITION TO EASTERLY AND SHIFT SOUTHWARD DURING THE
DAY ON SATURDAY AND INTO SATURDAY NIGHT.  AT THIS TIME...THE SURFACE
GRADIENTS FOR SUNDAY MORNING LOOK VERY SIMILAR TO SATURDAY MORNING.
HOWEVER...IT APPEARS THAT THE UPPER LEVEL SUPPORT WILL WEAKEN A BIT
UP NORTH...WHILE REALLY KICKING IN FOR SAN DIEGO COUNTY.

BESIDES THE WINDS...MUCH WARMER CONDITIONS WILL ALSO DEVELOP ACROSS
THE REGION FOR SATURDAY THROUGH MONDAY...WITH SUNDAY AND MONDAY
BEING THE WARMEST DAYS OF THE WEEK...AS TEMPERATURES ACROSS THE
INLAND VALLEYS FLIRT WITH THE 80 DEGREE MARK.  THIS RIDGE OF HIGH
PRESSURE WILL GRADUALLY WEAKEN DURING THE MIDDLE OF THE WORK
WEEK...WITH A GRADUAL COOLING TREND DEVELOPING ACROSS THE REGION.

&&

.AVIATION...
121600Z...UNRESTRICTED VIS WILL CONTINUE THROUGH THIS EVENING...WITH
BKN-SCT CLD LAYERS AOA FL150...BECOMING FEW-SCT OVERNIGHT. ISOLATED
-SHRA/DZ WITH DOWNDRAFTS POSSIBLE THROUGH MID MORNING...MAINLY OVER
THE LOWER DESERTS. A SHALLOW MARINE LAYER IS EXPECTED TO RETURN
TONIGHT...WITH AREAS OF LOW CLOUDS 500-1000 FT MSL DEVELOPING ALONG
THE COAST AFTER 13/05Z. CONFIDENCE IN STRATUS BASES IS LOW-MOD. ANY
STRATUS IS EXPECTED TO CLEAR THE COAST BY 16-18Z FRIDAY MORNING.

&&

.MARINE...
A MODERATE NORTHWEST SWELL GENERATED BY A STORM OVER THE
NORTH-CENTRAL PACIFIC IS EXPECTED TO ARRIVE IN THE COASTAL WATERS
SATURDAY...PEAKING AT 6 FEET/16 SECONDS SOUTH OF SAN CLEMENTE ISLAND
MONDAY EVENING...LOWERING TUESDAY. THIS SWELL WILL LIKELY BRING
ELEVATED SURF CONDITIONS AND STRONG RIP CURRENTS TO EXPOSED WEST
FACING BEACHES MONDAY INTO EARLY TUESDAY.

&&

.FIRE WEATHER...
GRADUAL RH RECOVERY THROUGH FRIDAY WITH OFFSHORE FLOW WEAKENING
TODAY...THEN TURN ONSHORE FRIDAY. MODERATE TO STRONG OFFSHORE WINDS
WILL DEVELOP AGAIN FRIDAY NIGHT/SATURDAY WITH GUSTS OF 50 MPH OR
MORE THROUGH AND BELOW THE FAVORED CANYONS AND PASSES. THE
WARM...DRY OFFSHORE FLOW WILL LOWER HUMIDITIES INTO THE SINGLE
DIGITS AND TEENS OVER THE WEEKEND...ELEVATING THE WILDFIRE DANGER.
GUSTY WINDS CONTINUE INTO SUNDAY. CONTINUED WARM AND DRY MONDAY AND
TUESDAY WITH LIGHTER OFFSHORE WINDS.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

PUBLIC...PALMER
AVIATION/MARINE...TS
FIRE...MOEDE