000
FXUS66 KSGX 031800
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
955 AM PST TUE DEC 3 2019

.SYNOPSIS...
TODAY WILL BE CLOUDY AND MILD AS TROPICAL MOISTURE STREAMS IN FROM 
THE SOUTH. LIGHT RAIN WILL BEGIN LATER TONIGHT FOLLOWED BY PERIODS 
MODERATE TO HEAVY RAIN WEDNESDAY AS THE TROUGH MOVES THROUGH. SNOW 
WILL BE MAINLY LIMITED TO THE MOUNTAINS ABOVE 7,000 FEET. THURSDAY 
AND FRIDAY WILL BE DRY AND A LITTLE WARMER. A LOW PRESSURE TROUGH 
THIS WEEKEND WILL BRING SMALL CHANCES FOR LIGHT PRECIPITATION. 

&&

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

THE MID AND HIGH LEVEL OVERCAST TODAY IS BEING BROUGHT TO US BY A 
TROPICAL MOISTURE CONNECTION THAT WILL SATURATE THE ATMOSPHERE FROM 
THE TOP DOWN TODAY. DEEP LAYER MOISTURE ADVECTION WILL RAISE THE 
PRECIPITABLE WATER FROM 0.52" THIS MORNING TO 1.25" WEDNESDAY 
MORNING IN SOCAL. 

THERE ISN'T MUCH CHANGE TO THE FORECAST REGARDING THE STORM TIMING 
AND INTENSITY. LIGHT RAIN BEGINS TONIGHT FOLLOWED BY A PERIOD OF 
MODERATE TO HEAVY RAIN WEDNESDAY MORNING INTO EARLY AFTERNOON ALONG 
THE SURFACE COLD FRONT. WPC HAS ALL AREAS FROM THE COAST TO THE 
MOUNTAINS IN A RISK OF EXCESSIVE RAINFALL. THE SOUTH FACING SLOPES 
OF THE SAN BERNARDINO MOUNTAINS WILL BE A PRIMARY FOCAL POINT FOR 
THE HEAVIEST RAIN DUE TO A COMBINATION OF STRONG INSTABILITY, 
SURFACE CONVERGENCE, AND OROGRAPHICS THAT WILL ENHANCE THE 
PRECIPIATION RATES AND AMOUNTS. 

PROJECTED RAIN AMOUNTS REMAIN UNCHANGED. ORANGE, SOUTHWESTERN SAN 
BERNARDINO, AND WESTERN RIVERSIDE COUNTIES WILL GET 0.75 TO 1.25 
INCH AT LOWER ELEVATIONS TO 2 TO 3 INCHES IN THE MOUNTAINS WITH 
ISOLATED GREATER AMOUNTS. FOR SAN DIEGO COUNTY, AMOUNTS WILL RANGE 
FROM AROUND 0.75 INCH NEAR THE COAST TO 1.5 TO 2.5 INCHES IN THE 
MOUNTAINS WITH LOCALLY GREATER AMOUNTS. IN THE HIGH DESERT, ONE TO 
TWO-THIRDS OF AN INCH WITH MOSTLY ONE-THIRD INCH OR LESS IN THE 
LOWER DESERTS. 

SNOW LEVELS WILL REMAIN NEAR 8000 FT WEDNESDAY MORNING WILL LOWER TO 
7000 FEET IN THE AFTERNOON AND TO AROUND 6000 FEET WEDNESDAY NIGHT. 
SATURATED GROUND AND MOUNTAIN SNOW FROM THE THANKSGIVING STORM WILL 
INCREASE THE POTENTIAL FOR ISOLATED FLASH FLOODING. MELTING SNOW 
SHOULD CONTRIBUTE TO THE RUNOFF IN PORTIONS OF THE MOUNTAINS. STREET 
FLOODING IN THE COASTAL AND VALLEY AREAS IS MOST LIKELY IN LOW LYING 
AREAS PRONE TO FLOODING AND IN AREAS WITH POOR DRAINAGE. 

THE RAIN WILL TRANSITION TO SHOWERS BEHIND THE COLD FRONT WEDNESDAY 
AFTERNOON BEFORE ENDING LATE WEDNESDAY NIGHT. WEAK HIGH PRESSURE 
BUILDS IN THURSDAY AND FRIDAY FOR DRY, MILD WEATHER. 

OVER THE WEEKEND A LARGE, CLOSED LOW PRESSURE SYSTEM OFF THE WEST 
COAST NEAR THE OREGON WILL DRIFT SOUTHEAST SUNDAY AND MONDAY. AREAS 
OF LIGHT PRECIPITATION COULD DEVELOP SATURDAY WITH A PERIOD OF MORE 
WIDESPREAD PRECIPITATION IS SUNDAY AFTERNOON AND EVENING NEAR THE 
TROUGH AXIS. MONDAY SHOULD BE DRIER AND A LITTLE WARMER. 

&&

.AVIATION... 
031700Z...BKN-OVC HIGH CLOUDS AT/ABOVE 15000 FT MSL WILL PREVAIL 
TODAY WITH UNRESTRICTED VIS. CLOUDS WILL GRADUALLY LOWER THIS 
EVENING TO 6000 FT MSL, WITH RAIN DEVELOPING AFTER MIDNIGHT. OVC 
CLOUD BASES AFTER 08Z TUE WILL MOSTLY BE 1500-3000 FT MSL, LOCALLY 
1000 FT MSL WITH AREAS OF VIS 2-4 MILES AND HIGHER TERRAIN OBSCURED. 
SOME IMPROVEMENT IN CIGS AND VIS ARE EXPECTED AFTER 20Z WED. AREAS 
OF WEST WINDS 20-30 KNOTS WITH GUSTS TO 40 KNOTS WILL DEVELOP AFTER 
17Z WED FROM THE MOUNTAIN CRESTS EAST TO THE DESERT FOOTHILLS.

&&

.MARINE... 
SOUTHERLY WINDS WITH GUSTS EXCEEDING 20 KTS ARE EXPECTED WEDNESDAY 
MORNING LEADING TO HAZARDOUS BOATING CONDITIONS. WINDS WILL SWITCH 
TO THE WEST BY WED AFTERNOON. THERE IS ALSO A SLIGHT CHANCE OF 
THUNDERSTORMS WED. A SMALL CRAFT ADVISORY IS IN EFFECT FROM 2 AM TO 
2 PM WEDNESDAY. NO ADDITIONAL MARINE WEATHER HAZARDS ARE EXPECTED TO 
THURSDAY THROUGH SUNDAY.

&&

.BEACHES...
THE SURF WILL CONTINUE TO DIMINISH THE REST OF TODAY. THE HIGH SURF 
ADVISORY WILL EXPIRE AT 10 AM. 

&&

.SKYWARN... 
SKYWARN ACTIVATION MAY BE NEEDED ON WEDNESDAY. 

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...HIGH SURF ADVISORY UNTIL 10 AM PST THIS MORNING FOR ORANGE 
     COUNTY COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS.

PZ...SMALL CRAFT ADVISORY FROM 2 AM TO 2 PM PST 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...MOEDE
AVIATION/MARINE/BEACHES...MAXWELL

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