High Surf Advisory 8, NWS San Diego, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
930 PM PST WED DEC 9 2015

.SYNOPSIS...
DENSE FOG FROM A SHALLOW MARINE LAYER WILL REDUCE VISIBILITIES
TO LESS THAN A QUARTER MILE IN THE SOME OF THE COASTAL AREAS
TONIGHT.  A DENSE FOG ADVISORY IS IN EFFECT UNTIL 8 AM THURSDAY.
COOLER THURSDAY AND FRIDAY WITH INCREASING CLOUDS...SCATTERED
SHOWERS...AND STRONG WINDS IN THE MOUNTAINS. LIGHT SNOW IS POSSIBLE
ABOVE 5000 FEET. GUSTY WINDS WILL IMPACT THE COASTAL WATERS WITH
HIGH SURF AND COASTAL FLOODING POSSIBLE FRIDAY AND SATURDAY DURING
HIGH TIDE. DRY AND SLIGHTLY WARMER OVER THE WEEKEND...THEN ANOTHER
CHANCE OF SHOWERS LATE SUNDAY INTO MONDAY NIGHT.

&&

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

DENSE FOG BLANKETED THE COASTAL AREAS AT 8 PM WITH 1/4 MILE VIS
AT FULLERTON...OCEANSIDE...CARLSBAD...MONTGOMERY FIELD AND BROWN
FIELD AT 8 PM. PRESSURE GRADIENTS REMAIN WEAKLY OFFSHORE SO
THERE WILL NOT BE MUCH CHANGE IN THE MARINE LAYER DEPTH FOR THE
NEXT SEVERAL HOURS. A DENSE FOG ADVISORY IS IN EFFECT UNTIL 8
AM THURSDAY. CLOUD BASES WILL BEGIN TO LIFT LATE TONIGHT OR EARLY
THURSDAY MORNING ONCE THE PRESSURE GRADIENTS TREND MORE STRONGLY
ONSHORE AHEAD OF THE APPROACHING TROUGH OVER THE PACIFIC.

THE TROUGH WILL BRING QUITE A CHANGE FROM WHAT WE HAVE SEEN OVER THE
PAST 5 DAYS WHEN MAX TEMPS WERE WAY ABOVE AVERAGE. IN ADDITION TO
COLDER WEATHER...THIS POTENT STORM HAS A 120KT JET CORE THAT WILL
TRACK DIRECTLY OVER SOCAL FRIDAY MORNING BRINGING STRONG WINDS TO THE
MOUNTAINS AND DESERTS. 850 MB WINDS PEAK AT 50-55KT OVER THE MTNS.
A HIGH WIND WATCH IS IN EFFECT FOR THE SAN JACINTO AND SAN DIEGO
COUNTY MOUNTAINS...AS WELL AS THE SAN GORGONIO PASS.

SHOWERS WILL BEGIN MOVING INTO THE AREA THURSDAY EVENING. PRECIP
WILL START OUT LIGHT AND SCATTERED THURSDAY NIGHT...WITH BETTER
CHANCES FOR MODERATE SHOWERS OR PERHAPS EVEN A THUNDERSTORM FRIDAY
AFTERNOON WITH THE SURFACE COLD FRONT. THIS WILL BE COINCIDENT WITH
STRONG PVA AND COLD AIR ALOFT THAT WILL DESTABILIZE THE ATMOSPHERE.

FORECAST PRECIPITATION AMOUNTS REMAIN UNCHANGED FROM THE DAY SHIFT
WITH 0.05-0.15 INCHES FOR ORANGE COUNTY AND THE INLAND EMPIRE...0.10-
0.25 INCHES IN THE SAN DIEGO COUNTY COAST/VALLEYS...0.25-0.50 INCHES
IN THE SAN BERNARDINO AND RIVERSIDE COUNTY MOUNTAINS...0.35-0.75
INCHES IN THE SAN DIEGO COUNTY MOUNTAINS...AND A TRACE TO 0.05
INCHES IN THE DESERTS. SNOW LEVELS START OUT AT AROUND 8000-9000
FEET...THEN LOWER TO AROUND 6000 FEET LATE THURSDAY NIGHT...5500
FEET FRIDAY MORNING...5000 FEET FRIDAY AFTERNOON AND 4500 FEET
FRIDAY EVENING. A TRACE TO A FEW INCHES OF SNOW COULD OCCUR.

...FROM PREVIOUS DISCUSSION...

NORTHERLY FLOW ALOFT AND SOME WEAK OFFSHORE FLOW AT THE SURFACE WILL
KICK IN ON SATURDAY WITH SOME SLIGHT WARMING AND DRYING SATURDAY
INTO SUNDAY. BY LATE SUNDAY...WE TURN BACK ONSHORE WITH A POTENT BUT
FAST MOVING TROUGH BEGINNING TO MOVE DOWN THE WEST COAST. ALTHOUGH
THERE ARE DIFFERENCES IN THE TIMING...ALL THE GLOBAL MODELS INDICATE
THE TROUGH DIGGING DOWN INTO THE REGION LATE SUNDAY NIGHT THROUGH
MONDAY AFTERNOON...BRINGING MORE WIDESPREAD PRECIPITATION...WITH
SNOW LEVELS POSSIBLY DROPPING DOWN TO 3000-4000 FEET. A SECONDARY
WAVE INDICATED BY THE MODELS MAY BRING ADDITIONAL LIGHT SHOWERS
OVERNIGHT MONDAY. PRECIP AMOUNTS WITH THIS SYSTEM ONCE AGAIN APPEAR
TO BE LIGHT. HOWEVER...WINDS WILL ONCE AGAIN BE STRONG FOR THE SAME
LOCATIONS AS THE THURSDAY NIGHT/FRIDAY STORM. AS ONE WOULD
EXPECT...THE TROUGH WILL PRODUCE ANOTHER COOL DOWN...WITH DAY-TIME
HIGHS LOWERING TO 10-20 DEGREES BELOW NORMAL MONDAY AND TUESDAY.
WEAK OFFSHORE FLOW WILL OCCUR TUESDAY...AND CONTINUE INTO
WEDNESDAY...WITH SOME WARMING TAKING PLACE BY WEDNESDAY.

&&

.AVIATION...
100500Z...COAST/VALLEYS...FG WITH VIS TO 1/4 SM WILL CONTINUE ALONG
PORTIONS OF THE COAST OVERNIGHT. LOW CLOUD BASES WERE 300-700 FT MSL
WITH TOPS AROUND 900 FT MSL. A WEAK COASTAL EDDY WILL HELP LIFT
CEILINGS A FEW HUNDRED FEET OVERNIGHT. CONDITIONS WILL IMPROVE
AROUND 16Z THU MORNING. FEW/SCT LOW CLOUDS THROUGH THE DAY
THU...THEN POSSIBLE -SHRA THU EVENING.

MTNS/DESERTS...SCT HIGH CLOUDS WITH UNRESTRICTED VIS THROUGH THU
MORNING. COASTAL MTN SLOPES LOCALLY OBSCURED BELOW 4000 FT MSL IN
SCT-BKN LOW CLOUDS. -SHRA POSSIBLE BEGINNING THU EVENING. WEST WINDS
INCREASING THROUGHOUT THE DAY THURSDAY OVER MTN RIDGES AND ALONG
DESERT MTN SLOPES. WINDS WILL PEAK FRIDAY WITH GUSTS NEAR 60 KT
POSSIBLE.

&&

.MARINE...
900 PM...AREAS OF DENSE FOG WILL CONTINUE
OVERNIGHT...WITH VIS AS LOW AS 1/4 MILE. STRONG NORTHWEST
WINDS...AND A LARGE NW SWELL WILL ARRIVE THURSDAY NIGHT AND CONTINUE
THROUGH EARLY SUNDAY. SEE LAXMWWSGX FOR DETAIL ON THE SMALL CRAFT
ADVISORY IN EFFECT. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
ARE POSSIBLE AT TIMES THU EVENING THROUGH EARLY SATURDAY.

&&

.BEACHES...
900 PM...A LARGE NORTHWEST SWELL WILL PRODUCE HIGH SURF
EARLY FRIDAY THROUGH SUNDAY MORNING. WINDS AND HIGH TIDES WILL
COMBINE WITH THE LARGE SWELL TO THREATEN BEACHES WITH MINOR FLOODING
AND EROSION. FOR DETAILS...SEE THE BEACH HAZARDS STATEMENT FOR
DETAILS...LAXCFWSGX.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...HIGH WIND WATCH FROM THURSDAY EVENING THROUGH FRIDAY EVENING FOR
     RIVERSIDE COUNTY MOUNTAINS-SAN DIEGO COUNTY MOUNTAINS-SAN
     GORGONIO PASS NEAR BANNING.

     BEACH HAZARDS STATEMENT FROM LATE THURSDAY NIGHT THROUGH SUNDAY
     AFTERNOON FOR ORANGE COUNTY COASTAL AREAS-SAN DIEGO COUNTY
     COASTAL AREAS.

     DENSE FOG ADVISORY UNTIL 8 AM PST THURSDAY FOR ORANGE COUNTY
     COASTAL AREAS-ORANGE COUNTY INLAND AREAS-SAN DIEGO COUNTY
     COASTAL AREAS.

PZ...SMALL CRAFT ADVISORY FROM 4 PM THURSDAY TO 10 AM PST SUNDAY FOR
     COASTAL WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER
     AND OUT TO 30 NM-WATERS FROM SAN MATEO POINT TO THE MEXICAN
     BORDER EXTENDING 30 TO 60 NM OUT INCLUDING SAN CLEMENTE
     ISLAND.

&&

PUBLIC...MOEDE
AVIATION/MARINE/BEACHES...JJT