Area Forecast Discussion
Issued by NWS San Diego, CA

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908
FXUS66 KSGX 130448 RRA
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
847 PM PST FRI FEB 12 2016

.SYNOPSIS...

TEMPERATURES LOWER A FEW DEGREES ON SATURDAY AS THE RIDGE OF HIGH
PRESSURE WEAKENS. ANOTHER WARM-UP EXPECTED SUNDAY THROUGH TUESDAY AS
THE RIDGE ALOFT RE-BUILDS AND STRONGER OFFSHORE FLOW MOVES IN.
STRONG AND GUSTY NORTHEAST TO EAST WINDS POSSIBLE IN THE
PASSES...CANYONS AND COASTAL FOOTHILLS SUNDAY THROUGH TUESDAY...WITH
THE STRONGEST WINDS ON MONDAY. BY NEXT WEDNESDAY...THE RIDGE WILL
WEAKEN AND ONSHORE FLOW RETURNS...RESULTING IN DECREASING
TEMPERATURES. A LOW PRESSURE TROUGH WILL CONTINUE TO COOLING TREND
AND MAY BRING SOME SHOWERS TO THE REGION ON THURSDAY.

&&

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

LIGHT OFFSHORE FLOW TO NEARLY NEUTRAL FLOW HAS DEVELOPED THIS
EVENING. ON A SMALLER SCALE...A WEAK MARINE INVERSION IS PUSHING A
BATCH OF FOG AND VERY LOW CLOUDS TOWARDS THE SOCAL COAST ATTM.
ALREADY SEEING SOME LIGHT FOG BEING REPORTED AT A FEW SITES IN SAN
DIEGO COUNTY ATTM. EXPECT BETTER COVERAGE OF FOG TO REACH THE SAN
DIEGO COUNTY COAST BETWEEN 10 PM AND MIDNIGHT...SPREADING INTO
ORANGE COUNTY AFTER MIDNIGHT. DENSE FOG WILL BE POSSIBLE DURING THIS
TIMEFRAME ALONG THE COAST AND A FEW MILES INLAND. THE HIGH
RESOLUTION MODELS ARE INDICATING A DIURNAL LIGHT OFFSHORE PUSH WILL
DEVELOP TOWARDS DAYBREAK...WHICH SHOULD DRY OUT AND PUSH THE FOG AND
LOW CLOUDS BACK OFFSHORE BY DAYBREAK.

SATURDAY WILL BE SLIGHTLY COOLER...BUT STILL CONSIDERABLY ABOVE
NORMAL...AS SOME COOLING TAKES PLACE ALOFT AND OFFSHORE FLOW REMAINS
VERY WEAK. ANOTHER WARM-UP IS STILL LIKELY TO COMMENCE ON
SUNDAY...REALLY GETTING IT`S ACT TOGETHER FOR MONDAY AND TUESDAY
WITH TEMPERATURES ONCE AGAIN REACHING UP TO 20 DEGREES ABOVE NORMAL.
STRONG DIURNALLY DRIVEN OFFSHORE WINDS WILL BE POSSIBLE SUNDAY NIGHT
THROUGH MONDAY...POSSIBLY REACHING WIND ADVISORY LEVELS THROUGH THE
PASSES AND IMMEDIATELY BELOW THE PASSES ALONG THE COASTAL AND
VALLEY SLOPES.

...REMAINDER OF PREVIOUS DISCUSSION...ISSUED TODAY AT 128 PM PST...

THE RIDGE STARTS TO WEAKEN AND WE TURN BACK ONSHORE DURING THE DAY
WEDNESDAY AS A TROUGH APPROACHES THE WEST COAST...CREATING COOLER
CONDITIONS. THE LONG-RANGE MODELS ARE STILL IN A FAIR AMOUNT OF
DISAGREEMENT REGARDING HOW DEEP AND STRONG THE TROUGH WILL BE AS IT
MOVES INLAND ON THURSDAY. THE 12Z GFS IS PRETTY SIMILAR TO THE 06Z
RUN...SHOWING A WEAK TROUGH AND ASSOCIATED PRECIPITATION MOVING BY
TO OUR NORTH...LEAVING US MOSTLY DRY. HOWEVER...THE 12Z ECMWF IS
MUCH STRONGER...WETTER AND SLOWER FOR SOUTHERN CALIFORNIA. THE 12Z
CANADIAN SEEMS TO SHOW COMPROMISE BETWEEN THE ECMWF AND GFS.
CONSIDERING THAT 2 OF THE 3 LONG RANGE MODELS CONSISTENTLY SHOW
PRECIP FOR THURSDAY...HAVE INCREASED THE POPS A BIT. AT THE VERY
LEAST...EXPECT THE COOLING TREND TO CONTINUE INTO THURSDAY.

&&

.AVIATION...

130430Z...COAST/VALLEYS...PATCHY DENSE FOG POSSIBLE TONIGHT ALONG
THE IMMEDIATE COAST...WITH LOW CLOUD BASES AROUND 200 FT AND VIS
AROUND 1/2 SM. OFFSHORE DRAINAGE WINDS SHOULD PUSH AWAY ANY FOG THAT
FORMS BY EARLY SAT MORNING. LOW CLOUDS AND FOG WILL LIKELY DEVELOP
ALONG THE COAST LATE SAT EVENING. FORECASTER CONFIDENCE IS MODERATE.

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

&&

.MARINE...

830 PM...FOG WITH VISIBILITY 1SM OR LESS WILL CONTINUE TO DEVELOP
OVER THE COASTAL WATERS THROUGH SATURDAY MORNING. VISIBILITY WILL
IMPROVE BY MID SATURDAY MORNING. OTHERWISE...NO HAZARDOUS MARINE
WEATHER IS EXPECTED SATURDAY AFTERNOON THROUGH TUESDAY.

&&

.BEACHES...

830 PM...A LONG-PERIOD SWELL FROM 290 DEGREES WILL PEAK SATURDAY AT
9 FT/18 SEC. THIS WILL CONTINUE HIGH SURF OF 4 TO 8 FEET THROUGH
SUNDAY...WITH HIGHEST SETS NORTH OF NEWPORT BEACH AND SOUTH OF DEL
MAR. A HIGH SURF ADVISORY REMAINS IN EFFECT THROUGH 8 PM SUNDAY.
SWELL AND SURF WILL SUBSIDE MONDAY.

&&

.FIRE WEATHER...

LIGHT OFFSHORE WINDS WILL CONTINUE THROUGH SATURDAY...THEN OFFSHORE
WINDS STRENGTHEN A LITTLE SUNDAY...WITH NORTHEAST TO EAST GUSTS 25-
40 MPH IN THE PASSES/CANYONS AND COASTAL FOOTHILLS...AND THEN
STRENGTHEN FURTHER ON MONDAY...WITH NORTHEAST TO EAST GUSTS 40-50
MPH...AND UP TO 60 MPH IN THE PASSES/CANYONS AND COASTAL FOOTHILLS.
THE OFFSHORE FLOW WILL COMBINE WITH VERY WARM CONDITIONS AND MINIMUM
RELATIVE HUMIDITIES IN THE SINGLE DIGITS TO TEENS TO CREATE ELEVATED
TO POSSIBLY CRITICAL FIRE WEATHER CONCERNS ON MONDAY. OVERNIGHT
HUMIDITY RECOVERIES LOOK TO BE POOR TO LOCALLY MODERATE.

HUMIDITY WILL START TO INCREASE WEDNESDAY AS ONSHORE FLOW RETURNS
AND A TROUGH APPROACHES FROM THE PACIFIC. THIS TROUGH COULD PRODUCE
WETTING RAINS NEXT THURSDAY.

&&

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

&&

.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...JMB/HARRISON
AVIATION/MARINE/BEACHES...JJT



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