Area Forecast Discussion
Issued by NWS San Diego, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KSGX 202014
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
114 PM PDT MON OCT 20 2014

.SYNOPSIS...
PLEASANT FALL WEATHER WILL PREVAIL ACROSS THE SOUTHLAND THROUGH
TUESDAY AS A LOW PRESSURE TROUGH ALOFT TRACKS INLAND. THE ONSHORE
FLOW WILL BECOME LOCALLY GUSTY IN THE MOUNTAINS AND DESERT PASSES...
AND WILL MAINTAIN THE MARINE LAYER AND ASSOCIATED CLOUDS WEST OF THE
MOUNTAINS. BY WEDNESDAY...THE MARINE LAYER WILL BE SHRINKING BACK TO
THE COAST AS HIGH PRESSURE BUILDS ALOFT AND THE SURFACE FLOW
WEAKENS. IT WILL BE MUCH WARMER ON THURSDAY AND FRIDAY...BUT THE
NIGHTS WILL BE COOL UNDER CLEAR SKIES AND LIGHT WINDS. ONSHORE FLOW
WILL RETURN AGAIN NEXT WEEKEND AS ANOTHER TROUGH SWINGS ACROSS THE
WEST WITH COOLER DAYS AND A RETURN OF MARINE CLOUDS AND LOCAL FOG.



&&

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

MARINE STRATUS WAS STUBBORN TO CLEAR THE COAST AND WESTERN VALLEY
AREAS THIS MORNING. BY 1 PM THERE WAS STILL SOME ALONG THE IMMEDIATE
COAST AND A FEW MORE CUMULUS HAD POPPED OVER THE HIGHER MTN CRESTS.
SKIES WERE CLEAR OVER AND DESERTS. SURFACE PRESSURE GRADIENTS WERE
WEAK ONSHORE AT MIDDAY AND WINDS WERE LIGHT.

THE MARINE LAYER CLOUDS WILL SPREAD BACK INLAND AGAIN OVERNIGHT BUT
ARE EXPECTED TO BURN OFF MORE RAPIDLY ON TUE SUE TO THE ADVECTION OF
DRIER AND COOLER AIR FROM THE NW. THIS WILL RESULT IN FAIR SKIES AND
YET ANOTHER FINE AUTUMN DAY ACROSS SOUTHERN CALIFORNIA. WESTERLY
WINDS WILL BECOME GUSTY THROUGH THE PASSES AND ON THE DESERTS SLOPES
LATE TODAY...AND CONTINUE INTO TUESDAY...OTHERWISE WINDS WILL BE
LIGHT. SLIGHTLY COOLER ON TUE AS WELL.

A VIGOROUS SHORT-WAVE TROUGH IS APPROACHING THE NOCAL COAST THIS
AFTERNOON AND WILL SWING THROUGH THE STATE TONIGHT. IT WILL MAINTAIN
ONSHORE FLOW...THE MARINE LAYER... AND AVERAGE DAYTIME TEMPERATURES
THROUGH TUE. ON WEDNESDAY...HEIGHTS WILL BEGIN TO BUILD ACROSS THE
SW IN THE WAKE OF THE TROUGH. HIGH PRESSURE WILL BUILD ACROSS THE SW
AND AMPLIFY NE OVER THE ROCKIES THROUGH FRI. THE ONSHORE FLOW AT THE
SURFACE WILL WEAKEN...AND MAY EVEN TURN WEAKLY OFFSHORE AS HIGH
PRESSURE BUILDS INLAND...RESULTING IN MUCH WARMER DAYS....ESPECIALLY
INLAND. BY SAT...ANOTHER TROUGH WILL APPROACH THE CA COAST AND BEGIN
TO FLATTEN THE RIDGE. THIS WILL BRING COOLER WEATHER NEXT WEEKEND.
THE LATEST 12Z GLOBAL MODEL RUNS ARE LOOKING MORE AGGRESSIVE WITH
THIS FEATURE. IF THAT TREND CONTINUES...A SMALL CHANCE FOR SOME
MARINE LAYER PRECIP MAY HAVE TO BE INTRODUCED W OF THE MTNS FOR SUN
MORNING.

DAYTIME TEMPERATURES ARE EXPECTED TO BE 5 TO 10 DEGREES F ABOVE
AVERAGE THU/FRI...THEN SLIP SAT...AND RETURN TO AVERAGE SUN.
OVERNIGHT LOWS WILL BE SLIGHTLY ELEVATED IN SOME AREAS...BUT WHERE
WINDS ARE LIGHT AND SKIES ARE CLEAR INLAND...THERE WILL BE LARGE
DIURNAL TEMP SWINGS DUE TO THE DRY AIR. MUCH COOLER AS WE MOVE
THROUGH NEXT WEEKEND.

GIVEN THE WEAK FLOW THAT WILL DEVELOP AFTER TUE...AND THE LINGERING
HIGH SFC DEWPOINTS ALONG THE COASTAL STRIP UNDER BUILDING HIGH
PRESSURE ALOFT...AREAS OF DENSE FOG MAY BECOME A CONCERN FOR AREAS
ALONG AND WEST OF THE MESAS WED THROUGH FRI MORNINGS.

LOOKING AHEAD TO NEXT WEEK...THERE IS FAIR AGREEMENT BETWEEN MODELS
THAT THE FLOW ALOFT WILL REMAIN WESTERLY OVER CA...KEEPING
TEMPERATURES CLOSE TO SEASONAL AVERAGES. UNFORTUNATELY THERE IS
LITTLE CHANCE FOR ANY PRECIPITATION EITHER.

&&

.AVIATION...
201930Z...AREAS OF LOW CLOUDS REMAIN OVER THE COASTAL AREAS THIS
AFTERNOON...WITH BASES AROUND 2000 FT AND TOPS TO 3500 FT. COASTAL
TAF SITES CONTINUE TO HAVE BKN-OVC CIGS 2000-2500 FT MSL. THESE
SHOULD BECOME SCT BETWEEN 21Z AND 00Z. LOW CLOUDS LIKELY TO RETURN
TO COASTAL TAF SITES AFT 00Z TUE...WITH BKN-OVC CIGS AROUND 2000 FT
MSL AND TOPS TO 3500 FT MSL. CLOUDS WILL SPREAD INLAND BY 12Z TUE
WITH REDUCED VIS IN AREAS WHERE TERRAIN AND CLOUDS INTERSECT.
CLEARING TO THE COAST IS EXPECTED BETWEEN 17Z AND 19Z TUE.

&&

.MARINE...
200 PM...NORTHWEST WINDS WILL GUST TO NEAR 20 KT IN THE OUTER
COASTAL WATERS NEAR SAN CLEMENTE ISLAND THIS EVENING. A NORTHWEST
SWELL WILL ARRIVE TONIGHT AND TUESDAY...AND WILL COMBINE WITH WIND
WAVES TO PRODUCE COMBINED SEAS OF 8 TO 10 FEET. THE NORTHWEST SWELL
WILL DECREASE THROUGH WEDNESDAY.

&&

.BEACHES...
200 PM...A LONG PERIOD NORTHWEST SWELL WILL ARRIVE AT BEACHES
TONIGHT AND TUESDAY. THIS WILL BRING LARGER SURF MAINLY TO WEST
FACING BEACHES SOUTH OF DEL MAR. STRONGER RIP CURRENTS WILL ALSO
DEVELOP...AND THE RIP CURRENT DANGER WILL BE GREATEST LATE TUESDAY
MORNING DURING THE TRANSITION FROM HIGH TIDE TO LOW TIDE. SEE
LAXSRFSGX FOR DETAILS.

&&

.FIRE WEATHER...
GUSTY WESTERLY WINDS THROUGH THE PASSES AND LOCALLY INTO THE
DESERTS...OTHERWISE NO FIRE WEATHER CONCERNS THROUGH TUESDAY. BY
WEDNESDAY...THE WEATHER WILL TRANSITION TO WARMER AND DRIER INLAND.
THE DRY AIR WILL TREND FARTHER WEST THROUGH FRIDAY WITH NEUTRAL
TO WEAK OFFSHORE FLOW PREVAILING. THERE MAY BE SOME LOCALLY GUSTY
EASTERLY WINDS TO 25 MPH BRIEFLY IN THE MOST WIND PRONE PASS AND
COASTAL FOOTHILL AREAS...OTHERWISE WINDS WILL BE GENERALLY 15 MPH OR
LESS THIS PERIOD. INLAND FROM THE COASTAL STRIP...RH WILL DROP TO
15-20 PERCENT EACH AFTERNOON WEDNESDAY THROUGH FRIDAY. COOLER WITH
HIGHER HUMIDITY AND ONSHORE FLOW RETURNING FOR THE WEEKEND.

&&

.SKYWARN...
SKYWARN ACTIVATION WILL NOT BE NEEDED TODAY.


&&

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

&&

$$

PUBLIC/FIRE WEATHER...JAD
AVIATION/MARINE/BEACHES...PG














USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.