Area Forecast Discussion
Issued by NWS San Diego, CA

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577
FXUS66 KSGX 131722
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
922 AM PST SAT FEB 13 2016

.SYNOPSIS...
AFTER A BRIEF ONSHORE PUSH TODAY...WINDS WILL TURN BACK OFFSHORE
AS HIGH PRESSURE REBUILDS ALOFT AND OVER THE GREAT BASIN. SOME
COASTAL FOG IS POSSIBLE AGAIN OVERNIGHT...BUT THEN NORTHEAST WINDS
WILL INCREASE AND BECOME LOCALLY STRONG AND GUSTY AGAIN BELOW SOME
PASSES AND CANYONS...ESPECIALLY ON MONDAY. THE SANTA ANA CONDITIONS
WILL CONTINUE THROUGH TUESDAY WITH VERY WARM AND DRY DAYS. THIS WILL
BE FOLLOWED BY COOLER WEATHER WEDNESDAY AS ONSHORE FLOW DEVELOPS. FOR
THURSDAY...A LOW PRESSURE TROUGH MOVING INLAND THROUGH THE STATE WILL
BRING A CHANCE OF SHOWERS.

&&

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

DENSE FOG WAS LIFTING THIS MORNING OVER COASTAL ORANGE COUNTY...
BUT ALSO WAS INDICATED OFFSHORE AT 9 AM PST. PATCHES OF HIGH CLOUDS
WERE ALSO VISIBLE IN SATELLITE IMAGERY OVER THE CA BIGHT...MOVING
EAST ACROSS SOCAL. THE 12Z MIRAMAR SOUNDING STILL HAD A SFC-BASED
INVERSION WITH A SLIGHT COOLING OF THE AIRMASS. WINDS BELOW 7K FT
WERE LIGHT AND VARIABLE. SURFACE PRESSURE GRADIENTS WERE RUNNING 6-7
MBS OFFSHORE FROM THE GREAT BASIN TO KSAN...AND 2-3 MBS ONSHORE TO
THE LOWER DESERTS. THE TREND WAS ONSHORE. MOST REPORTING SITES
ACROSS THE CWA HAD WINDS 10 MPH OR LESS.

GIVEN THE INCREASING ONSHORE FLOW TODAY AND SHALLOW MOIST LAYER...
FOG WILL BE A CONCERN ONCE AGAIN LATE THIS EVENING AND OVERNIGHT
OVER COASTAL AREAS. OFFSHORE TRENDS LATER IN THE NIGHT WILL LIKELY
NOT BE STRONG OR SOON ENOUGH TO CLEAR THE MOISTURE OFFSHORE
COMPLETELY. THE NEWER HIRES MODEL RUNS SHOULD HELP WITH GUIDANCE
IN THE NEAR TERM. IN THE MEANTIME...LOOKS LIKE ANOTHER FAIR AND MILD
DAY...BUT IT WILL BE COOLER...AND THE HUMIDITY WILL BE CONSIDERABLY
HIGHER WEST OF THE MTS.

FROM PREVIOUS DISCUSSION...


SURFACE HIGH PRESSURE OVER THE GREAT BASIN WILL BRING PERIODS OF
GUSTY SANTA ANA WINDS FOR LATE TONIGHT INTO TUESDAY...STRONGEST
FOR LATE SUNDAY NIGHT INTO MONDAY WITH ADVISORY STRENGTH WINDS
POSSIBLE...MAINLY BELOW THE CAJON PASS AND IN THE COASTAL
FOOTHILLS OF THE SANTA ANA MOUNTAINS.

FOR LATE WEDNESDAY INTO THURSDAY...A TROUGH OF LOW PRESSURE WILL
MOVE INLAND ALONG THE WEST COAST. THIS WILL BRING A CHANCE OF SHOWERS
FOR LATE WEDNESDAY THROUGH EARLY THURSDAY...THEN GRADUAL WARMING
INTO NEXT WEEKEND WITH PERIODS OF HIGH CLOUDS.

&&

.AVIATION...
131619Z...COAST...DENSE FOG/VERY LOW STRATUS 3-10 SM INLAND
PRODUCING VIS 1/4SM OR LESS WITH BASES 100-400 FT MSL AND TOPS 300-
600 FT MSL...WILL CLEAR OUT THROUGH 1800 UTC. 1800-14/0000
UTC...PRIMARILY UNRESTRICTED VIS AND FEW-SCT CLOUDS AOA 20000 FT
MSL. 14/0000-0900 UTC...DENSE FOG/LOW STRATUS GRADUALLY RE-
DEVELOPING 5-10 SM...AND LOCALLY 15 SM...INLAND...WITH BASES 100-600
FT MSL...TOPS 300-800 FT MSL AND AREAS OF VIS 1/4SM OR LESS. THESE
CONDITIONS CONTINUING THROUGH 14/0900-1600 UTC. CONFIDENCE IN
KSAN...KCRQ AND KSNA BEING IMPACTED WITH DENSE FOG AT TIMES IS
HIGH...WITH MODERATE CONFIDENCE IN TIMING.

VALLEYS/MTNS/DESERTS...UNRESTRICTED VIS AND FEW-SCT CLOUDS
AOA 20000 FT MSL THROUGH SUNDAY MORNING.

&&

.MARINE...
819 AM...DENSE FOG WITH VISIBILITY 1 NM OR LESS WILL CONTINUE OVER
THE COASTAL WATERS THROUGH MID-MORNING. ALTHOUGH VISIBILITY MAY
IMPROVE SOME LATE THIS MORNING INTO THE AFTERNOON...DENSE FOG IS
LIKELY TO RE-DEVELOP TONIGHT INTO MID-SUNDAY MORNING. A MARINE
WEATHER STATEMENT REMAINS POSTED. ALSO...A LARGE WEST-NORTHWEST
SWELL MAY CREATE COMBINED SEAS AT 9-10 FEET OVER PORTIONS OF THE
OUTER WATERS SOUTH OF SAN CLEMENTE ISLAND TODAY...WITH A DOMINANT
PERIOD OF AROUND 18 SECONDS. NO HAZARDOUS MARINE WEATHER IS EXPECTED
SUNDAY AFTERNOON THROUGH WEDNESDAY.

&&

.BEACHES...
819 AM...LATEST BUOY OBSERVATIONS FROM SAN CLEMENTE BASIN BUOY SHOW
WAVE HEIGHTS/PERIODS FROM THE WEST-NORTHWEST OF 10 FT/17
SECONDS...WHILE NEARSHORE BUOYS SHOW 5-6 FT/15-18 SECONDS.
THUS...IT APPEARS THAT THE SWELL IS PEAKING. THIS LONG-PERIOD SWELL
WEST-NORTHWEST SWELL FROM 290 DEGREES WILL CONTINUE AT AROUND THIS
LEVEL TODAY AND THEN LOWER DURING THE DAY SUNDAY. EXPECT STRONG RIP
CURRENTS AND HIGH SURF OF 5 TO 8 FEET TO CONTINUE THROUGH
SUNDAY...WITH HIGHEST SURF NORTH OF NEWPORT BEACH AND SOUTH OF DEL
MAR. A HIGH SURF ADVISORY REMAINS IN EFFECT THROUGH 8 PM SUNDAY. THE
SWELL AND SURF WILL CONTINUE TO LOWER MONDAY.

&&

.FIRE WEATHER...
WEAK ONSHORE FLOW EARLY TODAY...WILL TURN OFFSHORE ON SUNDAY...THEN
STRENGTHEN SUNDAY NIGHT INTO MONDAY FORCING VERY DRY AIR BACK OVER
THE COASTAL PLAIN THROUGH TUESDAY. STRONGEST WINDS ARE EXPECTED
BELOW THE CAJON PASS...AND THROUGH AND BELOW THE SANTA ANA MTS...BUT
AREAS BELOW THE SAN GORGONIO PASS AND IN THE WIND-PRONE COASTAL
FOOTHILLS OF THE SAN DIEGO COUNTY MTS WILL SEE LOCALLY STRONG
GUSTS...AS WELL AND VERY LOW MINIMUM RH MON THROUGH TUE. SEVERAL
HOURS OF CRITICAL OR NEAR-CRITICAL FIRE WEATHER ARE POSSIBLE IN
THESE AREAS.

NORTHEAST WINDS OF 15 TO 30 MPH ARE LIKELY ALONG THE COASTAL
FOOTHILLS LATE NIGHTS AND MORNINGS THROUGH TUESDAY...BUT LOCAL GUSTS
OF 45 TO AROUND 50 MPH ARE POSSIBLE LATE SUNDAY NIGHT THROUGH MONDAY
MORNING BELOW THE CAJON PASS AND NEAR THE SANTA ANA MTS. LOWEST
INLAND HUMIDITY OF 10-15 PERCENT IS EXPECTED BOTH MON/TUE...THEN
INCREASING ON WEDNESDAY AS ONSHORE FLOW DEVELOPS.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...HIGH SURF ADVISORY UNTIL 8 PM PST SUNDAY FOR ORANGE COUNTY
     COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS.

PZ...NONE.
&&

$$

PUBLIC/FIRE WEATHER...JAD/17
AVIATION/MARINE...HARRISON



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