High Surf Advisory 11, NWS San Diego, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
131 PM PDT SUN MAR 20 2016

.SYNOPSIS...
MORE MARINE CLOUDS...FOG AND PATCHY DRIZZLE ARE EXPECTED TO DEVELOP
AGAIN TONIGHT INTO MON MORNING ALONG THE MESAS AND WESTERN VALLEY
AREAS. COOLER AND BECOMING BREEZY MONDAY AND TUESDAY AS A LOW
PRESSURE TROUGH MOVES ACROSS THE REGION. THE DEEPENING MARINE LAYER
MAY LEAK SOME LIGHT RAIN OR DRIZZLE AT TIMES MONDAY NIGHT INTO EARLY
TUESDAY. THEN...MILD TO SEASONALLY WARM FOR THE REST OF THE WEEK
UNDER NORTHWEST FLOW ALOFT.

&&

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

LOW CLOUDS HAVE CLEARED COASTAL AREAS EARLY THIS AFTERNOON BUT REMAIN
OVER PORTIONS OF THE COASTAL WATERS. AT 1 PM PDT...SURFACE PRESSURE
GRADIENTS WERE TRENDING ONSHORE AT 3 TO 5 MBS FROM KSAN TO THE DESERTS
FUELING WESTERLY WINDS OF 15 MPH WITH ISOLATED GUSTS OF 25 TO 30 MPH
IN ONSHORE WIND-PRONE AREAS OF THE MOUNTAINS AND DESERTS.

THE MAIN FORECAST ISSUE OVER THE NEXT 24 HOURS WILL BE FOR FOG
FORMATION AND PERHAPS MORE PATCHY DRIZZLE. SYNOPTIC TRENDS SUGGEST
A MODEST DEEPENING OF THE MARINE LAYER AS ONSHORE TRENDS INCREASE.
HOWEVER...THE MODELED SURFACE PRESSURE FIELDS DO NOT STRENGTHEN
APPRECIABLY AND SFC-500 MB HEIGHTS BUMP UP SLIGHTLY. THE 12Z WRFEMS
SOUNDING AT KSAN SHOWS ALMOST NO CHANGE IN HEIGHT OF THE
INVERSION BASE...EVEN AS IT WEAKENS SEVERAL DEGREES. THIS SEEMS
REASONABLE AND WAS FOLLOWED FOR LOCATION OF FOG/PATCHY DRIZZLE
INLAND. THE WEAKENED INVERSION SHOULD ALLOW FOR MORE RAPID CLEARING
MID-TO-LATE MORNING ON MON OVER COASTAL/WESTERN VALLEYS.

ONSHORE FLOW WILL ALREADY BE RAMPING UP OVER THE MTS TONIGHT...AND
WILL CONTINUE TO INCREASE THROUGH MON INTO TUE WHEN A WIND ADVISORY
WILL LIKELY BE NEEDED FOR MTN/DESERT AREAS. COOLER MON/TUE...THEN
FAIR AND WARMER INTO NEXT WEEKEND UNDER DRY NW FLOW ALOFT.

LOW PRESSURE OVER THE GULF OF ALASKA IS FORECAST TO DROP SE AS A
TROUGH MON/TUE...THEN REFORM OVER EASTERN COLORADO ON WED. AS THE
TROUGH SLIDES SE...HEIGHTS WILL FALL OVER CALIFORNIA AND ONSHORE FLOW
WILL INCREASE WITH RAIN/SNOW SPREADING FROM NORTHERN INTO CENTRAL
PORTIONS OF THE STATE. FOR SOCAL...THE FALLING HEIGHTS AND INCREASING
ONSHORE FLOW WILL RESULT IN STRONG WESTERLY WINDS OVER THE MTS/
DESERTS WHERE ADVISORIES MAY BE NEEDED. A FEW SHOWERS COULD BREAK
OUT OVER SOCAL AS WELL...BUT THE QPF IS VERY LOW. ANY IMPACT WOULD
BE TO TRAVEL...ESPECIALLY DURING THE MORNING COMMUTES IF SOME ROADS
GET WET.

LOOKING AHEAD...BOTH 12Z RUNS OF THE ECMWF/GFS BUILD A STRONG RIDGE
BTWN 130-140W OVER THE EASTPAC LATE IN THE WEEK. THIS WILL ONCE AGAIN
BLOCK ANY STORMS FROM AFFECTING MUCH OF CA THROUGH NEXT WEEKEND. THE
MODELS ONLY SHOW THE RIDGE AMPLIFYING FURTHER INTO THE HIGH LATITUDES
EARLY NEXT WEEK...WHICH OPENS THE DOOR FOR SHORTWAVES TO DIG DOWN THE
EASTERN FLANK OF THE BLOCK INTO THE WESTERN U.S. EVEN THE 12Z ECMWF
HAS JUMPED ON BOARD (IN A BIG WAY) WITH THE GFS/GEM RUNS IN DEEPENING
A TROUGH ACROSS THE WEST.

WHILE CONFIDENCE IN THE DETAILS OF THIS REMAINS LOW...THE MAIN UPSHOT
OF THE MODEL CONSENSUS SHOULD ENSURE COOLER WEATHER ACROSS SOCAL
EARLY NEXT WEEK. IF THE TROUGH DIGS ENOUGH...SOME PRECIP WITH LOW
MOUNTAIN SNOW LEVELS ARE POSSIBLE HERE BY THE END OF THE MONTH...BUT
PROSPECTS DO NOT LOOK GOOD AT THIS POINT FOR MAKING UP THE PRECIP
DEFICIT WE ARE ACCRUING IN MARCH.

&&

.AVIATION...

201530Z...COAST/VALLEYS...MOSTLY CLEAR...EXCEPT FOR AREAS OF LOW
CLOUDS OVER THE COASTAL WATERS. LOW CLOUDS WITH BASES AROUND 700 FT
MSL AND TOPS TO 1500 FT MSL WILL RETURN TO THE COASTAL AIRPORTS
AFTER 03Z MONDAY AND SPREAD 10-15 MILES INLAND OVERNIGHT...WITH VIS
1-3SM AND LOCALLY BELOW 1SM OBSCURING HIGHER TERRAIN. EXPECT LOW
CLOUDS AND FOG TO CLEAR TO THE COAST BY 18Z MON. CONFIDENCE IN THE
TIMING IS MODERATE AT BEST. OTHERWISE SCATTERED CLOUDS AOA 15000 FT
AND UNRESTRICTED VISIBILITY THROUGH MONDAY.

MOUNTAINS/DESERTS...SCATTERED HIGH CLOUDS AND UNRESTRICTED
VISIBILITY WILL CONTINUE THROUGH MONDAY.

&&

.MARINE...

200 PM...NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH MONDAY. WNW
WINDS GUSTING 20-30 KT ARE POSSIBLE OVER THE COASTAL WATERS MONDAY
EVENING THROUGH WEDNESDAY. THE STRONGEST WINDS ARE EXPECTED ON
TUESDAY. COMBINED SEAS WILL BUILD TO 8-11 FT OVER THE OUTER WATERS
TUESDAY INTO WEDNESDAY.

&&

.BEACHES...

200 PM...A 6 FT SWELL FROM 290 DEGREES WITH A 14 SECOND PERIOD WILL
CONTINUE TO GENERATE SURF OF 3 TO 5 FT WITH STRONG RIP CURRENTS. THE
SWELL AND SURF WILL LOWER SLIGHTLY ON MONDAY. A SERIES OF LARGER WNW
SWELLS WITH SHORTER PERIODS WILL BRING HIGHER SURF TUESDAY INTO
WEDNESDAY...THEN SWELL AND SURF WILL LOWER LATE WEDNESDAY.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 8 PM MONDAY TO 2 AM PDT WEDNESDAY 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...JAD
AVIATION/MARINE/BEACHES...PG