Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 281645
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
844 AM PST SAT FEB 28 2015

.SYNOPSIS...LOW PRESSURE MOVING SOUTH ALONG THE CALIFORNIA COAST
WILL WILL BRING COOLER WEATHER AND PERIODS OF SHOWERS INTO EARLY
TUESDAY...DECREASING TUESDAY AFTERNOON. THERE WILL BE STRONG GUSTY
WEST WINDS IN THE MOUNTAINS AND LOCALLY INTO THE DESERTS INTO THIS
AFTERNOON. DRY AND WARMER FOR THE LATTER HALF OF THE WEEK WITH
PERIODS OF LOCALLY GUSTY NORTHEAST WINDS AT TIMES.

&&

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

ZONE FORECAST UPDATED TO REDUCE CLOUD COVER WEST OF THE MTS TODAY
AND LOWER POPS SLIGHTLY.

SATELLITE IMAGERY THIS MORNING SHOWED CLOUD BANDS MOVING ONSHORE
FROM THE COASTAL WATERS AND CONCENTRATED OVER THE MOUNTAINS...
OTHERWISE SKIES WERE PARTLY CLOUDY. THE STRONGEST WINDS OF 25-35 MPH
WITH GUSTS TO AROUND 45 MPH WERE CONFINED TO WIND-PRONE AREAS OF THE
MOUNTAINS. THE 12Z MIRAMAR SOUNDING HAD A 1500 FT SATURATED LAYER
TOPPED BY A WEAK INVERSION NEAR 5700 FT. WESTERLY WINDS EXCEEDED 40
KT ABOVE 9K FT. PW WAS 0.75 INCH.

THROUGH 8:30 AM PST...RADAR HAD A SMATTERING OF SHOWERS DRIFTING
EAST OFF THE COASTAL WATERS. PRECIP AMOUNTS FOR THE PAST 6 HOURS
WERE MOSTLY UNDER ONE-TENTH OF AN INCH. AMOUNTS WERE GREATEST ON THE
COASTAL SLOPES.

SURFACE LOW PRESSURE INLAND WILL WEAKEN THIS EVENING AS A BROAD...
POSITIVELY TILTED LOW PRESSURE TROUGH ORIENTED FROM AROUND BOISE TO
MORRO BAY DRIFTS SOUTH TOWARD POINT CONCEPTION. MOUNTAIN SLOPE WINDS
WILL DECREASE BY EVENING AS THE PRESSURE GRADIENT RELAXES.
SCATTERED...MOSTLY LIGHT SHOWERS ARE LIKELY TO CONTINUE AS THE LOW
APPROACHES AND COOLER AIR ALOFT CONTINUES TO DESTABILIZE THE
ATMOSPHERE.

LATEST GLOBAL MODELS SHOW THE TROUGH SLOWLY WEAKENING AND BECOMING
MORE NORTH-SOUTH ORIENTED AS IT DRIFTS SOUTH ALONG THE COAST THROUGH
MONDAY. AT THE SAME TIME...ANOTHER STRONG WAVE WILL DROP SOUTH ALONG
THE COAST...REINFORCING THE COLD AIR ALOFT AND POSSIBLY BRINGING
ANOTHER ROUND OF SHOWERS AND ISOLATED THUNDERSTORMS MON NIGHT INTO
TUE. HEIGHTS/THICKNESS WILL GRADUALLY RISE AFTER TUE AS THE RIDGE
OFFSHORE BUILDS BACK OVER CA BRINGING A RETURN OF OFFSHORE FLOW AND
FAIR...WARMER WEATHER FOR THE LATTER HALF OF THE WEEK.

WIND...A WIND ADVISORY WILL EXPIRE OVER THE NORTHERN DESERTS BY NOON
TODAY...AND OVER THE REMAINDER OF THE MTS/DESERTS BY 4 PM. GUSTS OF
45 TO 55 MPH WILL CONTINUE IN WIND-PRONE AREAS...MAINLY THROUGH THE
SAN GORGONIO PASS AND DESERT MTN SLOPES UNTIL THEN.

PRECIP...SCATTERED...LIGHT SHOWERS TODAY WITH AN EMPHASIS OVER THE
COASTAL SLOPES DUE TO UPSLOPE FLOW. THE SNOW LEVEL WAS AROUND 5500
FT THIS MORNING AND SHOULD HOLD MUCH OF THE DAY...THEN DROP TONIGHT
TO AROUND 5000 FEET. AN INCREASE IN THE PRECIP RATE IS LIKELY LATE
TONIGHT OR ON SUN AS COLDER AIR AND BETTER DYNAMICS ALOFT DEVELOP.
HOWEVER...IT LOOKS LIKE THE BEST ORGANIZED LIFT WILL OCCUR SOUTH OF
THE BORDER...WHICH MAY CLIP THE TIJUANA RIVER VALLEY. SHOWERS WILL
BECOME MORE NUMEROUS WITH HEAVIER RAINFALL RATES POSSIBLE SUN NIGHT
THROUGH TUE MORNING AS THE COLDER AIR ALOFT OVERSPREADS THE REGION.
WE SHOULD ALSO SEE THE EMPHASIS FOR CONSISTENTLY HEAVIER PRECIP
AMOUNTS MOVE AWAY FROM THE MTNS AND TOWARD THE COASTAL AREAS WITH
TIME.

ALL OF EXTREME SOUTHERN SAN DIEGO COUNTY HAS A CHANCE TO GET MORE
RAINFALL THAN CURRENTLY FORECAST IF THE MOISTURE AND ENERGY FORECAST
TO MOVE OVER NORTHERN BAJA CLIPS THAT REGION AS INDICATED BY THE
LATEST GFS AND WRFEMS RUNS.

SNOWFALL...A WINTER STORM WARNING IS IN EFFECT ABOVE 5000 FT FROM
LATE THIS AFTERNOON THROUGH MON AFTERNOON WITH THE SNOW LEVEL
FALLING TO 4800 TO 5200 FT. THE WARNING MAY BE PREMATURE WITH THE
LATEST HIRES MODELS NOT INDICATING MUCH PRECIP OVERNIGHT...BUT SOME
SNOW AND FREEZING CONDITIONS ARE STILL LIKELY. HEAVIER CONVECTIVE
SNOWFALL LOOKS LIKE A BETTER BET MAY BE SUN AND SUN NIGHT. LATEST
CIPS ANALOGS FOR THIS TYPE OF SYSTEM STILL FAVOR 8 INCH AMOUNTS IN
THE HIGHER MTS BY LATE TUE.

&&

.AVIATION...281600Z...A MIX OF SCT-OVC CLOUD LAYERS BETWEEN 1500-
6000 FT WILL PERSIST ALONG AND WEST OF THE MOUNTAINS THROUGH THE
OVERNIGHT HOURS. SCATTERED SHOWERS WILL ALSO OCCUR TODAY...WITH
BRIEF VIS REDUCTIONS TO 3 SM AND CIGS AS LOW AS 1000 FT MSL IN THE
HEAVIEST SHOWERS. SHOWERS WILL BECOME MORE NUMEROUS AFTER 08Z
SUNDAY. WEST WINDS WILL CONTINUE OVER THE REGION...WITH STRONGEST
WINDS OVER THE MOUNTAIN RIDGES AND THE DESERTS SLOPES THROUGH 00Z.
MODERATE UDDFS/LLWS ARE POSSIBLE OVER AND EAST OF THE MTNS. WINDS
WILL GRADUALLY WEAKEN THIS EVENING AND OVERNIGHT.

&&

.MARINE...800 AM...WEST-NORTHWEST WINDS 12-18 KT WITH GUSTS 18-25 KT
AND STEEP SEAS SEAS WILL CONTINUE THROUGH EARLY AFTERNOON. WINDS
WILL BEGIN TO WEAKEN LATE THIS AFTERNOON...WITH WINDS BECOMING 5-10
KT BY SUNDAY MORNING. A SHORT PERIOD SWELL AT 4-6 FT AND 7-9 SECONDS
WILL CONTINUE TO PRODUCE CHOPPY SEA THROUGH TONIGHT. A SMALL CRAFT
ADVISORY REMAINS IN EFFECT UNTIL 1 PM THIS AFTERNOON. PERIODS OF
SHOWERS WILL OCCUR THROUGH MONDAY NIGHT...WITH ISOLATED
THUNDERSTORMS POSSIBLE SUNDAY THROUGH MONDAY NIGHT. FOR FORECAST
DETAILS...SEE LAXCWFSGX.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...WIND ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR COACHELLA VALLEY-
     RIVERSIDE COUNTY MOUNTAINS-SAN DIEGO COUNTY DESERTS-SAN
     DIEGO COUNTY MOUNTAINS-SAN GORGONIO PASS NEAR BANNING.

     WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 4 PM PST MONDAY
     FOR RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO COUNTY
     MOUNTAINS-SAN DIEGO COUNTY MOUNTAINS ABOVE 5000 FEET.

     WIND ADVISORY UNTIL NOON PST TODAY FOR APPLE AND LUCERNE VALLEYS.

PZ...SMALL CRAFT ADVISORY UNTIL 1 PM PST THIS AFTERNOON FOR COASTAL
     WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER AND OUT
     TO 30 NM-WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER
     EXTENDING 30 TO 60 NM OUT INCLUDING SAN CLEMENTE ISLAND.

&&

$$

PUBLIC...JAD
AVIATION/MARINE...BA


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