Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 211608
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
905 AM PDT MON APR 21 2014

.SYNOPSIS...
FAIR AND A LITTLE WARMER TODAY AFTER THE LOW CLOUDS AND FOG BURN OFF
LATER THIS MORNING. COOLER FOR TUESDAY AND WEDNESDAY...WITH A DEEPER
MARINE LAYER AND STRONG GUSTY WEST WINDS IN THE MOUNTAINS AND
DESERTS. WEAKER WINDS AND MODEST WARMING FOR THURSDAY AND FRIDAY. A
STRONGER TROUGH OF LOW PRESSURE FRIDAY NIGHT AND SATURDAY WILL BRING
COOLING...DEEPENING OF THE MARINE LAYER...STRONG GUSTY WEST WINDS IN
THE MOUNTAINS AND DESERTS...AND A CHANCE OF PRECIPITATION. DRY WITH
SLOW WARMING FOR SUNDAY INTO NEXT MONDAY.

&&

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

THE MORNING SOUNDING SHOWS THE MARINE LAYER ABOUT 1600 FT DEEP WITH
AN INVERSION OF ABOUT 7 DEGREES CELSIUS. THIS ALLOWED LOW CLOUDS
AND FOG TO SPREAD ABOUT 15 MILES INLAND...WITH LOCALLY DENSE FOG
WHERE CLOUDS AND TERRAIN INTERSECT. THE CLOUDS AND FOG ARE BEGINNING
TO BURN OFF INLAND...AND THE RELATIVE WEAKNESS OF THE INVERSION
SHOULD RESULT IN CLEARING TO THE COAST BY LATE THIS MORNING.
TEMPERATURES TODAY SHOULD BE A FEW DEGREES HIGHER THAN YESTERDAY
WITH A WEAK HIGH PRESSURE RIDGE OVER SOCAL.

A COASTAL EDDY SHOULD REDEVELOP TONIGHT AND THE MARINE LAYER DEEPEN
AHEAD OF A LOW PRESSURE TROUGH APPROACHING FROM THE NORTHWEST. THIS
WILL CAUSE LOW CLOUDS TO SPREAD INLAND TO THE COASTAL SLOPES BY TUE
MORNING...WITH AREAS OF FOG WHERE CLOUDS AND TERRAIN INTERSECT.

FOR TUE AND WED...IN ADDITION TO THE DEEPENING MARINE LAYER AND MORE
EXTENSIVE LOW CLOUDS WEST OF THE MTNS...THE LOW PRESSURE TROUGH
MOVING INLAND WILL BRING STRONG AND GUSTY WEST TO NORTHWEST WINDS IN
THE MOUNTAINS AND DESERTS. IT WILL ALSO BRING ENOUGH COOLING SO THAT
DAYTIME TEMPS WILL BE NEAR OR A FEW DEGREES ABOVE SEASONAL AVERAGES.
THE WINDS WILL BE STRONGEST ON TUE WITH GUSTS MOSTLY AROUND 50
MPH...BUT LOCAL GUSTS TO 60 MPH ARE EXPECTED IN THE MORE WIND-PRONE
AREAS.

AS THE TROUGH MOVES EAST...A WEAK TRANSIENT RIDGE WILL BRING MOSTLY
FAIR CONDITIONS WITH WEAKER WINDS AND DAYTIME TEMPERATURES SLIGHTLY
ABOVE SEASONAL AVERAGES.

FOR FRI...ANOTHER LOW PRESSURE TROUGH MOVING IN FROM THE NORTHWEST
WILL BRING INCREASING ONSHORE FLOW...A DEEPER MARINE LAYER FOR MORE
WIDESPREAD LOW CLOUDS WEST OF THE MTNS...GUSTY WEST WINDS IN THE
MOUNTAINS AND DESERTS...AND LOWER TEMPERATURES.

AS THE LOW PRESSURE TROUGH MOVES INLAND ON SAT...IT WILL CONTINUE
THE COOLING TREND...WITH INCREASING CLOUDS AND A CHANCE FOR
PRECIPITATION ALONG AND WEST OF THE MOUNTAINS. SNOW LEVELS COULD
LOWER TO BETWEEN 5000 AND 6000 FT. GUSTY WEST TO NORTHWEST WINDS
WILL CONTINUE IN THE MTNS AND DESERTS.

DRY WITH A WARMING TREND AND WEAKER WINDS FOR SUN AND MON AS THE
TROUGH MOVES EAST AND A HIGH PRESSURE RIDGE BUILDS IN FROM THE WEST.

&&

.AVIATION...
211535Z...COAST/VALLEYS...STRATUS ABOUT 15-20 SM INLAND...WITH BASES
700-1000 FT MSL...TOPS AROUND 1500 FT MSL AND WIDESPREAD VIS 2-5
SM...WILL CLEAR TO THE COASTAL WATERS THROUGH 1900 UTC. 1900-22/0000
UTC...MOSTLY UNRESTRICTED VIS...WITH FEW-SCT CLDS...AND POSSIBLY BKN
IN SOME LOCATIONS...IN THE 900-1300 FT MSL LAYER WITHIN 3 SM OF THE
COAST. 22/0000-0600 UTC...STRATUS MOVING BACK INLAND 15-20 SM...AND
EVENTUALLY MOVING 20-35 SM INLAND BY 22/1200 UTC. CONFIDENCE
MODERATE TO HIGH ON TIMING. BASES/TOPS WILL BE 800-1200 FT
MSL/1500-1700 FT MSL DURING THE 22/0000-0600 UTC TIME-FRAME...THEN
RISING TO 1200-1600 FT MSL/1800-2200 FT MSL DURING THE 22/0600-1500
UTC TIME-FRAME. EXPECT AREAS OF VIS 3-5SM WITH LOCAL VIS AOB 1SM
10-35 SM INLAND.

MTNS/DESERTS...SKC THROUGH 2300 UTC...THEN FEW-SCT CLDS AOA 20000 FT
MSL 2300-22/1500 UTC. UNRESTRICTED VIS THROUGH TUESDAY MORNING.
STARTING 22/0300 UTC...SW TO W WIND GUSTS 25-35 KT OVER MTN
RIDGES...THROUGH PASSES/CANYONS...AND ALONG DESERT SLOPES AND INTO
FAVORED DESERT AREAS WILL RESULT IN MOD-STG UDDFS/LLWS OVER AND E OR
NE OF THE MTNS.

&&

.MARINE...
A TROUGH MOVING INLAND OVER CALIFORNIA WILL BRING STRONG WEST TO
NORTHWEST WINDS TUESDAY AND TUESDAY NIGHT...MAINLY FOR THE OUTER
WATERS. ALSO...FRESH SHORT-PERIOD WEST TO NORTHWEST SWELL WILL
ARRIVE TUESDAY AFTERNOON AND EVENING AND PEAK EARLY WEDNESDAY
MORNING. THE COMBINATION OF WINDS AND SWELL WILL MAKE CONDITIONS
HAZARDOUS FOR SMALL CRAFT. A SMALL CRAFT ADVISORY GOES INTO EFFECT
FOR THE OUTER COASTAL WATERS AT 9 AM TUESDAY AND CONTINUES THROUGH 2
AM WEDNESDAY. SEE LAXMWWSGX FOR DETAILS. WINDS WILL DIMINISH RAPIDLY
LATE TUESDAY NIGHT WHILE SWELL GRADUALLY DECREASES LATER WEDNESDAY.

FRIDAY AND SATURDAY...FAIRLY HIGH CONFIDENCE THAT ANOTHER WEATHER
SYSTEM WILL BRING MORE STRONG WINDS AND LARGE SWELL...RESULTING IN
HAZARDOUS CONDITIONS FOR SMALL CRAFT ONCE AGAIN. IT MAY ALSO BRING
HIGH SURF CONDITIONS TO THE BEACHES.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC...PG
AVIATION/MARINE...HARRISON





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