Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 200427
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
930 PM PDT SUN OCT 19 2014

.SYNOPSIS...
DRY AND SEASONAL WEATHER WILL CONTINUE THROUGH TUESDAY. HIGH
PRESSURE ALOFT BUILD OVER THE REGION BY WEDNESDAY AND STRENGTHEN
INTO FRIDAY. THE RIDGE AND WEAK OFFSHORE FLOW WILL BRING MUCH WARMER
DAYS AND LESS MARINE LAYER CLOUDS THROUGH THE END OF THE WEEK.
COOLER NEXT WEEKEND INTO EARLY NEXT WEAK AS THE RIDGE WEAKENS AND
ONSHORE FLOW RETURNS.

&&

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

PATCHY LOW CLOUDS WERE DEVELOPING OVER SAN DIEGO COUNTY AND THE
COASTAL WATERS. OTHERWISE SKIES ARE CLEAR THIS EVENING. LOW CLOUDS
WILL GRADUALLY FILL IN ALONG THE COAST AND INTO THE VALLEYS
TONIGHT...AND CLEAR BY MID-MORNING.

A TROUGH OFF THE WEST COAST AND ONSHORE FLOW WILL MAINTAIN FAIR AND
SEASONAL WEATHER MONDAY. ONSHORE PRESSURE GRADIENTS WILL INCREASE
DURING THE AFTERNOON AS THE TROUGH APPROACHES...GENERATING LOCALLY
GUSTY WINDS IN THE MOUNTAINS AND DESERTS. THE TROUGH AXIS WILL MOVE
THROUGH MONDAY NIGHT...WITH WEAKER ONSHORE FLOW AND COOL CONDITIONS
CONTINUING INTO TUESDAY UNDER DRY NORTHWEST FLOW ALOFT. THE MARINE
LAYER WILL REMAIN MODERATELY DEEP WITH LOW CLOUDS EXTENDING INTO THE
INLAND VALLEYS MONDAY NIGHT INTO TUESDAY.

FOR WED THROUGH SAT...AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL
BUILD OVER SOUTHERN CALIFORNIA AND GRADUALLY AMPLIFY AND SHIFT
EASTWARD OVER THE DESERT SOUTHWEST THROUGH THE PERIOD. SURFACE HIGH
PRESSURE BUILDING OVER THE GREAT BASIN WILL GENERATE SOME OFFSHORE
FLOW AS WELL. SURFACE PRESSURE GRADIENTS WILL BE WEAK...PEAKING AT
ABOUT -6 MB SAN-TPH WED MORNING...WITH VIRTUALLY NO UPPER LEVEL
SUPPORT. EXPECT JUST SOME LOCALLY BREEZY CONDITIONS IN THE WIND
PRONE AREAS WITH GUSTS AROUND 25-30 MPH AT BEST. THERE MAY BE JUST
ENOUGH OF AN OFFSHORE PUSH AT NIGHT TO KEEP ANY MARINE LAYER CLOUDS
AND FOG THAT SURVIVES BEYOND WEDNESDAY MORNING OUT OF THE COASTAL
AREAS. OVERALL WEATHER WILL REMAIN FAIR WITH A GRADUAL WARM UP AND
DRIER CONDITIONS THROUGH FRIDAY.

THE RIDGE WEAKENS BY SATURDAY AS ANOTHER LARGE TROUGH APPROACHES THE
WEST COAST. THERE ARE STILL SOME TIMING DIFFERENCES BETWEEN THE
MEDIUM RANGE MODELS WITH REGARDS TO WHEN THE TROUGH MOVES
THROUGH...WITH THE GEM ON THE FASTER END...THE GFS SOMEWHERE IN THE
MIDDLE BRINGING IT THROUGH SOMETIME SUNDAY...AND THE EC LAGGING
BEHIND BY ABOUT 24 HOURS. EITHER WAY WILL SEE A COOLING TREND NEXT
WEEKEND INTO EARLY NEXT WEEK WITH A RETURN OF ONSHORE FLOW AND
COASTAL LOW CLOUDS. PRECIPITATION...IF ANY...WILL BE LIMITED TO
MARINE LAYER DRIZZLE.


&&

.AVIATION...
200410Z...COAST/VALLEYS...AREAS OF STRATUS WILL DEVELOP IN THE
COASTAL AND VALLEY AREAS. TIME OF ARRIVAL AT AIRPORTS IS LOW
CONFIDENCE DUE TO THE PATCHY NATURE OF THE STRATUS...BUT THE STRATUS
WILL BECOME MORE WIDESPREAD AFTER 06-07Z...SO MOST AIRPORTS SHOULD
HAVE A BROKEN CIG BETWEEN ABOUT 07Z AND 16Z MONDAY. BASES WILL BE
2000-2500 FT MSL WITH TOPS TO 3500 FT MSL...WITH TERRAIN LOCALLY
OBSCURED. MOST VIS WILL REMAIN ABOVE 5 MI. MOSTLY SCT CONDITIONS
WILL PREVAIL IN COASTAL/VALLEY AREAS AFTER 16Z MONDAY. STRATUS WILL
DEVELOP AGAIN MONDAY NIGHT.

MOUNTAINS/DESERTS...MOSTLY CLEAR SKIES WITH UNRESTRICTED VIS WILL
PREVAIL THROUGH MONDAY NIGHT.

&&

.MARINE...
900 PM...NORTHWEST WINDS WILL GUST TO NEAR 20 KT IN THE OUTER
COASTAL WATERS NEAR SAN CLEMENTE ISLAND MONDAY EVENING. A LONG
PERIOD NORTHWEST SWELL WILL ARRIVE TUESDAY MORNING...PEAKING IN THE
OUTER WATERS WITH COMBINED SEAS OF 8 TO 10. NORTHWEST SWELL WILL
DECREASE WEDNESDAY.

&&

.BEACHES...
900 PM...THE LONG PERIOD NORTHWEST SWELL WILL AFFECT WEST FACING
BEACHES SOUTH OF DEL MAR TUESDAY/TUESDAY EVENING. LOCAL SURF TO 8
FEET WILL BE POSSIBLE...MOST LIKELY TUESDAY AFTERNOON/EVENING WHEN
THE SWELL WILL BE AT ITS PEAK. STRONG RIP CURRENTS WILL ACCOMPANY
THE ELEVATED SURF. THE RIP CURRENT DANGER WILL BE GREATEST LATE
TUESDAY MORNING DURING THE TRANSITION FROM HIGH TIDE TO LOW TIDE.

&&

.FIRE WEATHER...
NO FIRE WEATHER CONCERNS THROUGH TUESDAY. HOWEVER...THE WEATHER WILL
TRANSITION TO WARMER AND DRIER FOR THE LATTER HALF OF THE WEEK.
LOCALLY GUSTY EAST WINDS MAY DEVELOP AS EARLY AS WED MORNING IN THE
WIND PRONE AREAS WITH LOCAL GUSTS OF 25 MPH POSSIBLE AT TIMES.
EXCEPT IN THESE WIND PRONE AREAS NEAR THE FOOTHILLS AND
PASSES...MOST AREAS SHOULD SEE WINDS 15 MPH OR LESS THIS PERIOD.
INLAND FROM THE COASTAL STRIP...RH WILL DROP TO AROUND 15 PERCENT OR
LESS EACH AFTERNOON WEDNESDAY THROUGH FRIDAY. COOLER WITH HIGHER
HUMIDITY AND ONSHORE FLOW RETURNING BY SATURDAY.

&&

.SKYWARN...
SKYWARN ACTIVATION WILL NOT BE NEEDED ON MONDAY.

&&

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

&&

$$

PUBLIC/FIRE WEATHER...SS
AVIATION/MARINE/BEACHES...MAXWELL





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