High Wind in California, April 12 to 13, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
935 AM PDT SAT APR 12 2014

.SYNOPSIS...
UPPER LEVEL TROUGH OF LOW PRESSURE WILL MOVE INLAND ACROSS SOUTHERN
CALIFORNIA TODAY...WHILE ANOTHER DIGS SOUTH FROM THE PACIFIC
NORTHWEST.  AS A RESULT...COOLER CONDITIONS WILL PREVAIL...WITH A
STUBBORN MARINE LAYER SLOW TO CLEAR WEST OF THE MOUNTAINS.  STRONG
ONSHORE FLOW WILL CONTINUE ACROSS THE REGION...WITH GUSTY WEST WINDS
IN THE MOUNTAINS AND DESERTS.  DRY AND WARMER CONDITIONS WILL
DEVELOP FOR MONDAY AND TUESDAY...AS HIGH PRESSURE BUILDS BACK ACROSS
THE REGION...WITH SOME GUSTY OFFSHORE WINDS POSSIBLE.  ANOTHER
TROUGH OF LOW PRESSURE WILL MOVE INLAND ACROSS THE WEST FOR THE
LATTER HALF OF THE WEEK...BRINGING A RETURN OF WEAKER ONSHORE
FLOW...MORE SEASONAL TEMPERATURES...AND A RETURN OF NIGHT AND
MORNING COASTAL LOW CLOUDS AND FOG.

&&

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

WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL LOW SLOWLY OPENING UP AS IT
MOVES INLAND ACROSS SOUTHERN CALIFORNIA THIS MORNING.  AS A
RESULT...THE ONSHORE GRADIENTS ARE ON THE RISE...WITH A MUCH DEEPER
MARINE LAYER BLANKETS THE AREAS WEST OF THE MOUNTAINS.  THE 12Z KNKX
SOUNDING SHOWS THAT THE MARINE LAYER DEEPENED TO AROUND 3200 FEET
LAST NIGHT...WITH SURFACE OBSERVATIONS SHOWING THAT IT IS NOW AROUND
4000 FEET DEEP.  THE SOUNDING ALSO SHOWS THAT THE MARINE LAYER IS
RELATIVELY THIN...WHICH IS ALLOWING FOR A FEW SUN BREAKS.
HOWEVER...WITH THE ONSHORE GRADIENTS INCREASING THROUGH THE DAY
TODAY TO NEARLY 11 MBS BETWEEN SAN DIEGO AND DAGGETT...BELIEVE THAT
ONLY A PARTIAL CLEARLY WILL OCCUR.  GUSTY WEST WINDS WILL ALSO
DEVELOP IN THE MOUNTAINS AND DESERTS THIS AFTERNOON.  CURRENTLY THE
STRONGEST GUSTS ARE RUNNING BETWEEN 35 AND 45 MPH...BUT AS THE
GRADIENTS TIGHT AND UPPER LEVEL SUPPORT INCREASES THIS
AFTERNOON...GUSTS UP TO 55 MPH WILL BE POSSIBLE AT THE FAVORED
LOCATIONS.  THEREFORE...THE WIND ADVISORY LOOKS ON TRACK FOR THE
SOUTHERN MOUNTAINS AND DESERTS.  MEANWHILE...TEMPERATURES TODAY WILL
LIKELY RUN 8 TO 18 COOLER THAN YESTERDAY...WITH TEMPERATURES FALLING
BACK BELOW NORMAL.

WATER VAPOR IMAGERY ALSO SHOWS AN UPPER LEVEL TROUGH DIGGING SOUTH
ACROSS THE PACIFIC NORTHWEST THIS MORNING.  AS IT DIVES ACROSS THE
GREAT BASIN ON TONIGHT AND ON SUNDAY...STRONG ONSHORE FLOW WILL
CONTINUE ACROSS THE REGION...WITH OUR DEEP MARINE LAYER LINGERING
WEST OF THE MOUNTAINS.  FOR THIS REASON...COOL CONDITIONS WILL
PREVAIL THROUGH SUNDAY...EVEN THOUGH SOME INLAND AREAS MAY BE A
DEGREE OR TWO WARMER.

HIGH PRESSURE WILL THEN BUILD BACK ACROSS SOUTHERN CALIFORNIA FOR
THE FIRST PART OF THE WORK WEEK...WITH DRY AND WARMER CONDITIONS
DEVELOPING.  AT THIS TIME...IT APPEARS THAT SOME OFFSHORE WINDS WILL
DEVELOP BY MONDAY MORNING.  HOWEVER...THE MODELS ARE NOW ALL IN
AGREEMENT THAT THIS WILL BE A RELATIVELY WEAK OFFSHORE EVENT...WITH
JUST SOME LOCALLY GUSTY NORTHEAST TO EAST WINDS POSSIBLE THROUGH THE
FAVORED PASSES AND CANYONS.

A SERIES OF WEAK TROUGHS WILL THEN TAKE AIM AT THE WEST COAST FOR
THE LATTER PART OF THE WORK WEEK AND WEEKEND.  ALTHOUGH IT APPEARS
THAT DRY CONDITIONS WILL LIKELY PREVAIL...THE ONSHORE FLOW AND
COOLER CONDITIONS WILL LIKELY RETURN.  THE MARINE LAYER WILL ALSO
RETURN...WITH COASTAL LOW CLOUDS AND FOG POSSIBLE EACH NIGHT.

&&

.AVIATION...
121500Z...COAST/VALLEYS...WIDESPREAD LOW CLOUDS WEST OF THE MTNS
WITH BKN-OVC CIGS 2500-3000 FT MSL AND TOPS 3500-4000 FT MSL WILL
GRADUALLY BECOME SCT THROUGH 19Z. BETTER CLEARING IS MORE LIKELY
VCNTY KSAN...KCRQ AND KONT THAN AT KSNA. HIGHER TERRAIN WILL REMAIN
OBSCURED THROUGH 17Z WITH FOG REDUCING VIS TO 1-3SM WHERE CLOUDS AND
TERRAIN INTERSECT. LOW CLOUDS WITH BKN-OVC CIGS 2000-2500 FT MSL AND
TOPS 3000-3500 FT MSL WILL LIKELY RETURN TO THE COASTAL TAF SITES
BETWEEN 01Z AND 03Z. LOW CLOUDS WILL SPREAD INLAND TO THE COASTAL
SLOPES BY 09Z...OBSCURING HIGHER TERRAIN AND REDUCING VIS WHERE
CLOUDS AND TERRAIN INTERSECT.

ELSEWHERE...FEW-SCT CLOUDS AOA 15000 FT WITH UNRESTRICTED VIS
THROUGH SUNDAY MORNING.

MTNS/DESERTS...W TO SW WINDS 20-30 KT WITH GUSTS TO 45 KT WILL
CREATE MOD-STG UDDFS/LLWS OVER AND E OF THE MTNS THROUGH SUNDAY
MORNING.

&&

.MARINE...
WAVE MODELS INDICATE THAT COMBINED SEAS WILL REACH 8 FEET IN THE
OUTER WATERS FOR A FEW HOURS WED MORNING AS A 9-SECOND SWELL MOVES
IN AND WINDS INCREASE A LITTLE OUT OF THE NW.

OTHERWISE...NO SIGNIFICANT MARINE WEATHER CONDITIONS ARE EXPECTED
THROUGH FRIDAY.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...WIND ADVISORY FROM NOON TODAY TO 3 AM PDT SUNDAY FOR THE
     COACHELLA VALLEY...RIVERSIDE COUNTY MOUNTAINS...SAN DIEGO
     COUNTY DESERTS...SAN DIEGO COUNTY MOUNTAINS.

PZ...NONE.

&&

PUBLIC...PALMER
AVIATION/MARINE...PG