740
FXUS66 KSGX 310846
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
1246 AM PST WED DEC 31 2025
SYNOPSIS
A LOW PRESSURE SYSTEM OFF THE COAST WILL MOVE OVER THE
REGION THROUGH THURSDAY, BRINGING CLOUDY SKIES AND AREAS OF SHOWERS.
THE HEAVIEST RAIN WILL FALL LATE WEDNESDAY NIGHT THROUGH THURSDAY
MORNING. A PERIOD OF DRIER WEATHER WILL OCCUR FOR A SHORT TIME ON
FRIDAY. A SERIES OF WEAK WEATHER SYSTEMS WILL BRING ANOTHER
INCREASED CHANCE FOR LIGHT SHOWERS TO OCCUR OVER THE REGION BY
THIS WEEKEND, POTENTIALLY INTO EARLY NEXT WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SATELLITE IMAGERY THIS MORNING SHOWS A DYNAMIC AREA OF LOW PRESSURE
OFF TO OUR WEST PULLING IN CLOUDS AND SUBTROPICAL MOISTURE FROM THE
SOUTH. KIND OF LIKE YESTERDAY AFTERNOON, RADAR SHOWS VERY ELEVATED
SHOWERS, WHERE SOME FOLKS MAY BE ABLE TO SEE A SPRINKLE OR TWO.
HI-RES MODEL GUIDANCE SHOWS HIGH-LEVEL MOISTURE AND SHOWERS
BEGINNING TO OVERSPREAD THE AREA BY LATE MORNING INTO THE
AFTERNOON TODAY. HEAVIEST SHOWERS WILL BE ALONG THE COASTAL
SLOPES WITH LOWER ELEVATIONS RECEIVING LIGHT AMOUNTS. A FRONTAL
BOUNDARY WITH THE STORM SYSTEM WILL APPROACH THE AREA LATE
THIS EVENING THROUGH THURSDAY MORNING, WHERE THE HEAVIEST RAIN
WILL BE EXPECTED. AS THIS OCCURS, SOUTHERLY WINDS WILL STRENGTHEN
THIS EVENING AND OVERNIGHT AS WELL, MAINLY AT THE COAST. IF
PLANNING ANY NEW YEAR'S CELEBRATIONS TONIGHT, BE PREPARED FOR RAIN
SHOWERS ACROSS OUR ENTIRE FORECAST AREA, AS WELL AS SOME BREEZY
WINDS NEAR THE IMMEDIATE COAST NEAR 20 MPH AT TIMES. THIS
SUBTROPICAL MOISTURE RIDDEN PATTERN WILL CONTINUE THE MORE HUMID
AND WARMER EVENING TEMPERATURES OVER THE NEXT FEW NIGHTS AS WELL.
THE FRONTAL BAND WILL LIFT OVER REGION ON THURSDAY MORNING. THIS
WILL BE ASSOCIATED WITH SLIGHT INCREASED INSTABILITY AS THE VORT MAX
PASSES OVER SOCAL, SO A SLIGHT CHANCE OF THUNDERSTORMS HAVE BEEN
ADDED TO THE FORECAST FOR MUCH OF THURSDAY MORNING AND AFTERNOON FOR
AREAS WEST OF THE MOUNTAINS. ANY THUNDERSTORM WILL BE CAPABLE OF
PRODUCING HEAVIER RAINFALL, GUSTY WINDS AND SMALL HAIL. IN TERMS OF
RAINFALL, THE HEAVIEST IS EXPECTED ALONG THE COASTAL SLOPES OF THE
SAN BERN CO MOUNTAINS WITH 3-5" IN TOTAL BY THURSDAY NIGHT. CHANCES
FOR 1"+ OR MORE OF RAINFALL IS NEAR 50-60% IN ORANGE COUNTY AND
THE WESTERN INLAND EMPIRE, SLIGHTLY LOWER CHANCES IN NORTHERN SD
COUNTY. CHANCES BECOME CLOSER TO 15-30% FOR THE EASTERN PARTS OF
THE INLAND EMPIRE AND THE SAN DIEGO METRO. THE DESERTS WILL ALSO
RECEIVE RAINFALL, BUT MOST AREAS WILL SEE BETWEEN 0.25"-0.75".
SOME HOURLY RAIN RATES WILL BE ELEVATED AREAS SURROUNDING THE LA
BASIN, LEADING TO LOCALIZED FLOODING ON STREETS AND NEAR RECENT
BURN AREAS DURING THIS EVENT. SNOW LEVELS WILL REMAIN OVER 8,000
FEET, WITH MOST MOUNTAIN COMMUNITIES RECEIVING ONLY RAIN.
A BRIEF DRYING PERIOD WILL OCCUR BY FRIDAY AS THE WEATHER SYSTEM
EXITS TO THE EAST AND A WEAK RIDGE MOVES IN ITS PLACE. WHILE MOST
OF OUR REGION WILL LIKELY REMAIN CLOUDY, CHANCES FOR SUNSHINE AND
SLIGHTLY WARMER TEMPERATURES ARE IN THE FORECAST FOR THE DESERT
REGIONS. HIGHS IN THE HIGH DESERT WILL NEAR 60 DEGREES WITH HIGHS
NEAR 70 DEGREES ACROSS THE COACHELLA VALLEY AND ANZA BORREGO
DESERT AREAS.
ANOTHER PACIFIC STORM SYSTEM CURRENTLY IN THE GULF OF ALASKA WILL
MOVE CLOSER TO SOCAL BY THIS WEEKEND, PROVIDING ANOTHER CHANCE FOR
SHOWERS ON SATURDAY MORNING AND CONTINUE THROUGH THE WEEKEND.
WHILE EXACT TIMING OF THE RAIN AND RAIN TOTALS REMAINS UNCERTAIN,
IT IS LOOKING INCREASINGLY LIKELY THAT THIS RAIN EVENT WILL BE
LIGHTER THAN THE ONE WE ARE ABOUT TO SEE IN THE COMING DAYS. SNOW
LEVELS MAY BE SLIGHTLY LOWER BY THIS TIME PERIOD AS WELL. THIS
WILL CONTINUE THE NEAR AVERAGE TEMPERATURE AND MOSTLY CLOUDY
WEATHER PATTERN THAT WE WILL BE SEEING THIS WEEK. GLOBAL ENSEMBLE
MODELS START TO DIVERGE ON WHAT BECOMES OF THIS WEEKEND'S WEATHER
SYSTEM AND HOW IT EVOLVES BY THE FIRST HALF OF NEXT WEEK. PERIODS
OF SHOWERS REMAIN POSSIBLE FOR THIS ENTIRE TIME PERIOD AS SOME
MODELS SUGGEST A SERIES OF WEAK DISTURBANCES ROUNDING THE SOUTHERN
PORTION OF THE WEATHER SYSTEM. THOUGH THE EXACT DETAILS AREN'T IN
VIEW TOO WELL FOR NOW, A CLOUDIER, COOLER AND POTENTIALLY WETTER
PATTERN LOOKS TO REMAIN AS WE ENTER THE EARLY PART OF JANUARY.
AVIATION
310400Z...GENERALLY VFR CONDITIONS TONIGHT WITH BKN-OVC HIGH CLOUDS
8000-12000 FT. EASTERLY GUSTS NEAR 20-30 KTS IN THE MOUNTAIN PASSES
AND COASTAL SLOPES AND LOCALLY INTO VALLEYS WILL DIMINISH 06-09Z
WED. A LULL IS EXPECTED WEDNESDAY MORNING BEFORE GUSTS 20-30KTS
RETURN 18Z WED-00Z THU. SCT -SHRA MOVES IN FROM SOUTH TO NORTH
STARTING 12-15Z WED WITH BASES LOWERING TO 5000-7000 FT MSL.
INTERMITTENT MINOR VIS REDUCTIONS (4-6SM) POSSIBLE FROM THE COAST TO
THE MTNS INTO THE AFTERNOON HOURS. SHRA INCREASES IN COVERAGE AND
BECOMES HEAVIER STARTING 03-06Z THU WITH BASES LOWERING AGAIN TO
2000-4000 FT MSL. WIDESPREAD MVFR CIGS/VIS LIKELY WITH INTERMITTENT
IFR CIGS/VIS THROUGH THE OVERNIGHT HOURS.
MARINE
SOUTHEASTERLY WINDS START TO STRENGTHEN WEDNESDAY AFTERNOON, WITH
CONDITIONS HAZARDOUS TO SMALL CRAFT WEDNESDAY EVENING THROUGH
THURSDAY AFTERNOON, BRINGING SOUTH TO SOUTHEAST GUSTS TO 25 KNOTS.
WINDS TURN WESTERLY BEFORE DIMINISHING LATE THURSDAY AFTERNOON.
THEN, NO HAZARDOUS MARINE WEATHER CONDITIONS EXPECTED THROUGH
SATURDAY.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...FLOOD WATCH FROM THIS EVENING THROUGH THURSDAY EVENING FOR
ORANGE COUNTY COASTAL AREAS-ORANGE COUNTY INLAND AREAS-SAN
BERNARDINO COUNTY MOUNTAINS-SAN BERNARDINO AND RIVERSIDE
COUNTY VALLEYS-THE INLAND EMPIRE-SANTA ANA MOUNTAINS AND
FOOTHILLS.
PZ...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 3 PM PST THURSDAY
FOR COASTAL WATERS FROM SAN MATEO POINT TO THE MEXICAN
BORDER AND OUT TO 10 NM-WATERS FROM SAN MATEO POINT TO THE
MEXICAN BORDER EXTENDING 10 TO 60 NM OUT INCLUDING SAN
CLEMENTE ISLAND.
PUBLIC...APR
AVIATION/MARINE...KW
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