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000
FXUS66 KSGX 062116
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
123 PM PST FRI DEC 6 2013

.SYNOPSIS...
.A BROAD AREA OF COLD AIR ACROSS THE WESTERN HALF OF THE COUNTRY
WILL CONTINUE TO INFLUENCE OUR WEATHER THROUGH THE WEEKEND...
KEEPING TEMPERATURES BELOW NORMAL. A STORM ARRIVING SATURDAY WILL
REINFORCE THE COLD AIR...AND BRING RAIN AND SNOW SHOWERS TO THE
REGION...ALONG WITH STRONG WESTERLY WINDS IN THE MOUNTAINS AND
DESERTS. LOW SNOW LEVELS AND PERSISTENT SHOWERS IN SOME AREAS MAY
RESULT IN LOCALLY HEAVY SNOWFALL AT HIGHER ELEVATIONS. GRADUALLY
WARMER NEXT WEEK AS THE COLD AIR SHIFTS EAST.

&&

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


A DEEP MOIST LAYER AND DAYTIME HEATING HAS KEPT AREAS OF CUMULUS
CLOUDS DEVELOPING...MAINLY INLAND TOWARD THE COASTAL SLOPES. AT
MIDDAY...TEMPERATURES WERE STILL IN THE 50S TO AROUND 60 AT LOWER
ELEVATIONS. SURFACE PRESSURE GRADIENTS WERE WEAK AND WINDS LIGHT.

A BROAD AND COLD AREA OF LOW PRESSURE ACROSS THE WESTERN HALF OF THE
COUNTRY WILL BE REINFORCED BY A VIGOROUS SHORT-WAVE TROUGH SLIDING
SOUTH INTO THE PACIFIC NW THIS AFTERNOON...AND THROUGH THE GREAT
BASIN ON SATURDAY. THE GLOBAL MODELS ARE IN CLOSE AGREEMENT WITH THE
TIMING AND TRAJECTORY. FALLING SURFACE PRESSURE OVER THE GREAT BASIN
AND INCREASING WINDS ALOFT WILL RESULT IN STRONG WESTERLY WINDS/
GUSTS OVER THE MTN RIDGES AND LOCALLY INTO THE DESERTS SAT/SAT
NIGHT. SHOWERS WILL ACCOMPANY THE WAVE ACROSS CA AS IT SLIDES SE.
THE GLOBAL MODELS KEEP PRECIP LIGHT...BUT THE LOCAL MESOSCALE RUNS
OF THE WRF DO SHOW CONSIDERABLE OROGRAPHIC ENHANCEMENT INTO THE
MTNS. QPF FOLLOWED THE 06Z/12Z WRFEMS RUNS CLOSELY WITH SOME COASTAL
SLOPE ENHANCEMENT. LOW SNOW LEVELS...COMBINED WITH THE UPSLOPE MAY
RESULT IN SOME LOCAL HEAVY SNOWFALL ON THE HIGHER PEAKS. STRONG
WINDS WILL ACCOMPANY THE SNOW SHOWERS WHICH HAVE PROMPTED A WINTER
STORM WARNING FOR ALL HIGHER MOUNTAINS SAT/SAT NIGHT.

A HIGH WIND WARNING IS IN EFFECT FOR THE ADJACENT DESERTS ON SAT/SAT
NIGHT AS WELL. LOCAL WIND GUSTS TO 65 MPH OR MORE ARE POSSIBLE ON
THE DESERT SLOPES/FOOTHILLS. SNOWFALL WILL BE VARIABLE WITH THE
LATEST LOCAL MODEL GUIDANCE INDICATING 2 TO 8 INCHES AT HIGHER
ELEVATIONS...BUT LOCALLY UP TO 12 INCHES IS POSSIBLE BASED ON SOME
GUIDANCE. SNOW LEVELS GENERALLY 3500 TO 4500 FEET BUT MAY BE LOCALLY
LOWER AT ONSET OF THE PRECIP. SEVERAL INCHES MAY ACCUMULATE BELOW
4500 FEET...BUT ANY HEAVY SNOWFALL SHOULD BE AT THE HIGHEST
ELEVATIONS.

RAINFALL AMOUNTS LOOK LIGHT...GENERALLY FROM A FEW HUNDREDTHS OF AN
INCH TO ONE-QUARTER INCH COAST/VALLEYS...ONE-HALF INCH OR MORE ON
THE FOOTHILLS.

DRYING AND CONTINUED COOL FOR SUNDAY. A STRONG SURFACE HIGH BUILDING
SOUTH THROUGH NV MAY PRODUCE MODERATE TO STRONG OFFSHORE FLOW
THROUGH THE WIND FAVORED PASSES AND CANYONS ON SUN/MON. AT THIS
TIME ADVISORY STRENGTH WINDS LOOK LIKLEY IN SOME AREAS.

WARMER AND DRY WITH PERIODS OF OFFSHORE THROUGH THU OF NEXT WEEK.
ANOTHER TROUGH IS FORECAST TO APPROACH THE AREA FROM THE NW ON FRI.
BOTH THE 12ZGFS/ECMWF DETERMINISTIC RUNS GENERATE SOME LIGHT PRECIP
ON FRI SO SLIGHT CHANCES HAVE BEEN ADDED TO THE END OF THE FORECAST
PERIOD CONTINUED CHILLY NIGHTS WITH PATCHY FROST THROUGH TUE.

&&

.AVIATION...

.AVIATION...
062115Z...ALONG AND WEST OF THE MTS...LAYERS OF SCT-BKN CLOUDS
BETWEEN 4000-7000 FT MSL...OBSCURING TERRAIN AT TIMES THROUGH THIS
EVENING. CIGS WILL LOWER AHEAD OF AN APPROACHING SYSTEM OVERNIGHT.
ISOLATED TO SCATTERED SHOWERS WILL DEVELOP AS WELL AFTER 06Z...WITH
LOCAL VIS 4-6SM AND CIGS AS LOW AS 2500 FT MSL. MORE WIDESPREAD
SHOWERS WILL DEVELOP AFTER 15Z.

DESERTS...UNRESTRICTED VIS...WITH AREAS OF BKN-SCT CLDS 5000-8000 FT
MSL THROUGH SATURDAY. STRONG WESTERLY WINDS WILL RESULT IN MTN WAVE
ACTIVITY WITH MOD-STG UDDFS AND SURFACE WINDS GUSTING TO 50-60 KT ON
THE DESERT SLOPES SATURDAY AFTERNOON...REACHING THE DESERT FLOOR SAT
NIGHT.

&&

.MARINE...
A COLD TROUGH OF LOW PRESSURE WILL MOVE ACROSS SOUTHERN CALIFORNIA
ON SATURDAY...BRINGING WEST TO NORTHWEST WINDS 25-30 KT AND STEEP
SEAS OF 7 TO 9 FEET...AS HIGH 11 FEET IN THE OUTER WATERS. THE WINDS
AND STEEP SEAS WILL COMBINE TO CREATE ROUGH AND HAZARDOUS BOATING
CONDITIONS FOR SMALL CRAFT. LOCAL WIND GUSTS MAY REACH 35 KT AT
TIMES. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR BOTH THE INNER
AND OUTER COASTAL WATERS...STARTING AT 8 AM SATURDAY. WINDS AND SEAS
WILL START TO DIMINISH SUNDAY MORNING...WITH CONTINUALLY IMPROVING
CONDITIONS THROUGH THE DAY.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...WINTER STORM WARNING FROM 10 AM SATURDAY TO 4 AM PST SUNDAY FOR
     THE RIVERSIDE COUNTY MOUNTAINS...SAN BERNARDINO COUNTY
     MOUNTAINS...SAN DIEGO COUNTY MOUNTAINS.

     HIGH WIND WARNING FROM 10 AM SATURDAY TO 4 AM PST SUNDAY FOR THE
     APPLE AND LUCERNE VALLEYS...COACHELLA VALLEY...SAN DIEGO
     COUNTY DESERTS.

PZ...SMALL CRAFT ADVISORY FROM 8 AM SATURDAY TO 8 AM PST SUNDAY FOR
     THE WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER
     EXTENDING 30 TO 60 NM OUT INCLUDING SAN CLEMENTE ISLAND.

     SMALL CRAFT ADVISORY FROM 8 AM SATURDAY TO 3 AM PST SUNDAY FOR
     THE COASTAL WATERS FROM SAN MATEO POINT TO THE MEXICAN
     BORDER AND OUT 30 NM.

&&

$$

PUBLIC...JAD/MM
AVIATION/MARINE...TS