Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 041043
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
345 AM PDT MON MAY 4 2015

.SYNOPSIS...

A WEAK LOW PRESSURE SYSTEM OFF THE CALIFORNIA COAST WILL MOVE INLAND
TODAY BRINGING COOLING...GUSTY WEST WINDS IN THE MOUNTAINS AND
DESERTS...AND A SLIGHT CHANCE OF THUNDERSTORMS. SLIGHTLY WARMER FOR
TUESDAY AND WEDNESDAY. A COLDER...STRONGER LOW PRESSURE SYSTEM FROM
THE NORTH WILL BRING ADDITIONAL INLAND COOLING FOR THURSDAY AND
FRIDAY...GUSTY WEST WINDS IN THE MOUNTAINS AND DESERTS...AND CHANCES
FOR SHOWERS ALONG AND WEST OF THE MOUNTAINS. HIGH PRESSURE WILL
BRING WARMING AND DRYING NEXT WEEKEND WITH HIGH TEMPERATURES
RETURNING TO NEAR AVERAGE FOR NEXT SUNDAY AND MONDAY.

&&

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

.SHORT TERM (TODAY THROUGH WEDNESDAY)...

THE CENTER OF A WEAK LOW PRESSURE SYSTEM IS NEARING THE SOUTHERN
CALIFORNIA COAST AND WILL MOVE INLAND THROUGH SOUTHERN CALIFORNIA
TODAY. WEAK LIFT ASSOCIATED WITH DIFLUENCE AHEAD OF THE UPPER LOW
HAS TAPPED WEAK INSTABILITY...WITH THE WORKSTATION WRF SHOWING 700-
300 MB MOST UNSTABLE CAPE VALUES OF 200-300 J/KG OVER THE CENTRAL
AND SOUTHERN SAN DIEGO COUNTY VALUES...TO PRODUCE ISOLATED
THUNDERSTORMS OVERNIGHT. ONE EARLIER THUNDERSTORM MOVED FROM AROUND
EL CAJON TO NEAR LAKEWOOD BEFORE DISSIPATING AND PRODUCED SMALL
HAIL. A SECOND THUNDERSTORM...THAT WAS SOMEWHAT STRONGER AND
LARGER...MOVED ACROSS THE BORDER SOUTH OF DULZURA MORE RECENTLY
BEFORE DISSIPATING. BASED ON DUAL POL DATA AND AN EARLIER GROUND
TRUTH REPORT NEAR EL CAJON...THE STORM ALONG THE BORDER MOST LIKELY
PRODUCED NON-SEVERE HAIL AS WELL AS BRIEF HEAVY RAINFALL. CONDITIONS
REMAIN FAVORABLE EARLY THIS MORNING FOR ADDITIONAL ISOLATED
THUNDERSTORMS IN THE SAN DIEGO COUNTY VALLEYS. AS THE UPPER LOW
MOVES INLAND...THE CHANCE FOR THUNDERSTORMS WILL SHIFT TO THE
MOUNTAINS IN THE AFTERNOON AND END BY EARLY EVENING.

SLIGHT WARMING FOR TUESDAY UNDER WEAK HIGH PRESSURE AND SLIGHT
COOLING FOR WEDNESDAY FROM ANOTHER WEAK LOW PRESSURE SYSTEM.
CONTINUED ONSHORE FLOW WILL MAINTAIN A DEEP MARINE LAYER WITH NIGHT
AND MORNING COASTAL LOW CLOUDS AND FOG EXTENDING INLAND TO THE FAR
INLAND VALLEYS.

&&

.LONG TERM (THURSDAY THROUGH SUNDAY)...

FOR THURSDAY AND FRIDAY...A STRONGER AND COLDER LOW PRESSURE SYSTEM
FROM THE NORTH WILL BRING STRONGER ONSHORE FLOW AND INLAND COOLING
WITH GUSTY WEST WINDS IN THE MOUNTAINS AND DESERTS. IT WILL ALSO
BRING A CHANCE OF SHOWERS ALONG AND WEST OF THE MOUNTAINS. THE
MODELS ARE IN SOMEWHAT BETTER AGREEMENT WITH THE DETAILS WITH THE
CURRENT TIMING OF THE MOST SIGNIFICANT DYNAMICS BRINGING THE MOST
LIKELY TIME FOR PRECIPITATION TO FAR SOUTHERN CALIFORNIA FOR LATE
THURSDAY INTO THURSDAY NIGHT WITH A COLD FRONTAL PASSAGE. DRY WITH A
WARMING TREND FOR SATURDAY THROUGH MONDAY WITH HIGH TEMPERATURES
RETURNING TO NEAR AVERAGE FOR SUNDAY AND MONDAY.

&&

.AVIATION...
040930Z...COAST/VALLEYS...LOW CLOUDS WITH BASES FROM 1000-2000 FT
MSL AND TOPS NEAR 2500 FT MSL...WILL COVER MOST OF THE AREA THIS
MORNING. EXPECT HIGHER TERRAIN TO BE OBSCURED AT TIMES. LOW CLOUDS
WILL SLOWLY CLEAR TOWARDS THE COAST BY LATE THIS MORNING...THEN
RETURN THIS EVENING WITH SLIGHTLY HIGHER TOPS AND BASES. FORECASTER
CONFIDENCE IN STRATUS TIMING AND HEIGHTS IS MEDIUM TO HIGH.

MTNS/DESERTS...WEST WINDS WITH GUSTS TO 45KT WILL BE POSSIBLE THIS
AFTERNOON/EVENING AND COULD PRODUCE MDT TO STRONG UDDFS AND LLWS
OVER AND EAST OF THE MTNS. ISOLATED TSRA WILL BE POSSIBLE OVER THE
MTNS AND DESERTS THIS AFTN AND EVENING.

&&

.MARINE...
200 AM...NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH TUESDAY.
BREEZY NORTHWEST WINDS...WITH GUSTS OF 20 TO LOCALLY 25 KT...ARE
POSSIBLE IN THE AFTERNOONS WEDNESDAY THROUGH FRIDAY...MAINLY IN THE
OUTER WATERS NEAR SAN CLEMENTE ISLAND. A TROUGH MOVING ACROSS THE
REGION WILL CREATE A SLIGHT CHANCE OF SHOWERS THURSDAY AND FRIDAY.

&&

.BEACHES...

200 AM...LONG-PERIOD SOUTH SWELLS OF ABOUT 4 FT...WILL CONTINUE HIGH
SURF ALONG SAN DIEGO AND ORANGE COUNTY BEACHES THROUGH EARLY THIS
WEEK. WIDESPREAD SURF OF 3 TO 7 FT IS EXPECTED...WITH SETS OF 8 TO
12 FT POSSIBLE ALONG SOUTH-FACING BEACHES. STRONG RIP AND LONGSHORE
CURRENTS...BEACH EROSION AND MINOR TIDAL FLOODING OF LOW-LYING
COASTAL AREAS DURING THE EVENING HIGH TIDES IS EXPECTED. SURF WILL
SLOWLY LOWER THROUGHOUT THE WEEK. SEE LAXCFWSGX FOR DETAILS ON THE
HIGH SURF ADVISORY CURRENTLY IN EFFECT THROUGH TUESDAY EVENING.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...HIGH SURF ADVISORY UNTIL 11 PM PDT TUESDAY FOR ORANGE COUNTY
     COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS.

PZ...NONE.

&&

$$

PUBLIC...17
AVIATION/MARINE/BEACHES...PG


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