030
FXUS66 KSGX 310402
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
802 PM PST TUE DEC 30 2025
SYNOPSIS
MILD TONIGHT WITH THICK HIGH CLOUD COVER AND A FEW SPRINKLES AT
TIMES. BREEZY EAST WINDS CONTINUING ALONG THE COASTAL SLOPES AND
FOOTHILLS INTO WEDNESDAY. A LOW PRESSURE SYSTEM WILL BRING
PERIODS OF SHOWERS FOR NEW YEAR'S EVE AND NEW YEAR'S DAY WITH THE
POTENTIAL FOR MORE CLOUDY AND WET WEATHER BY THE END OF THE WEEK
INTO EARLY NEXT WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
EVENING UPDATE...
THICK HIGH CLOUDS ARE MOVING NORTH OVER THE AREA THIS EVENING.
BREEZY EASTERLY SANTA ANA WINDS CONTINUE ACROSS THE COASTAL
MOUNTAIN SLOPES, FOOTHILLS, AND LOCALLY INTO THE VALLEYS. THESE
WINDS HAVE KEPT TEMPERATURES IN THE LOW TO MID 70S ACROSS PARTS OF
THE COASTS AND SAN DIEGO COUNTY VALLEYS. THE HIGH CLOUD COVER AND
OFFSHORE FLOW COMBINATION WILL LEAD TO A MILD NIGHT FOR MOST AREAS
WEST OF THE MOUNTAINS. THERE COULD BE A FEW SPRINKLES HERE OR
THERE TONIGHT, BUT WITH THE EXTREMELY DRY SUBCLOUD LAYER DON'T
EXPECT ANY OF THIS TO RESULT IN ACCUMULATING PRECIPITATION. AS WE
GET SOME TOP-DOWN MOISTENING TOWARDS WEDNESDAY MORNING WITH THE
APPROACHING UPPER LEVEL LOW, PRECIPITATION CHANCES INCREASE TO
AROUND 50% THOUGH ANY ACCUMULATION WEDNESDAY MORNING WILL BE
LIMITED TO A FEW HUNDREDTHS OF AN INCH. OTHERWISE A LITTLE COOLER
ON WEDNESDAY WITH HIGHS AROUND SEASONAL AVERAGES.
PREVIOUS DISCUSSION...
FOR WED EVENING THROUGH THU...THIS IS THE PERIOD OF TIME WHEN MOST
OF THE RAINFALL WILL OCCUR AS THE CLOSED LOW TO THE SOUTHWEST
ACCELERATES TO THE NORTHEAST AND BECOMES AN OPEN WAVE. IT WILL
PRODUCE ENOUGH DYNAMIC FORCING FOR DEEP CONVECTION, RESULTING IN
PERIODS OF HEAVIER SHOWERS WHICH WILL BE MORE EFFICIENT AT
EXTRACTING MOISTURE FROM THE ATMOSPHERE. RAINFALL RATES DURING
HEAVIER SHOWERS WILL LIKELY RANGE FROM 0.3"-0.5" PER HOUR, WITH
ABOUT A 50% CHANCE OF EXCEEDING 0.5" PER HOUR. THE GREATEST
ACCUMULATIONS WILL BE IN THE SAN BERNARDINO MOUNTAINS AND ON THE
COASTAL SLOPES WHERE TOTALS WILL RANGE FROM ABOUT 1.9" EAST OF
THE CAJON PASS TO ABOUT 5" NEAR THE LA COUNTY LINE. ELSEWHERE,
RAINFALL AMOUNTS WILL RANGE FROM 0.9"-1.8" IN THE COASTAL AREAS,
0.9"-1.8" IN THE INLAND VALLEYS, 1.1"-2.2" IN THE SAN DIEGO AND
RIVERSIDE COUNTY MTNS, 0.25"-0.75" IN THE LOW DESERTS, AND
0.25"-0.9" IN THE HIGH DESERT.
THERE WILL BE A BREAK FROM THE PRECIP ON FRI AS A WEAK DYNAMIC
RIDGE BUILDS BETWEEN THE TROUGH MOVING EAST AND A LOW PRESSURE
SYSTEM MOVING SOUTHEAST OUT OF THE GULF OF AK. TEMPS WILL RISE
SLIGHTLY, ESPECIALLY IN THE LOW DESERTS WHERE TEMPS COULD CLIMB
BACK INTO THE 70S.
THE LOW FROM THE GULF OF AK WILL RESUME THE PRECIP FOR SAT-SUN.
THIS SYSTEM WILL BRING COLDER AIR BUT WILL HAVE LESS AVAILABLE
MOISTURE. TEMPS ON SAT AND SUN WILL BE IN THE 60S WEST OF THE MTNS
AND PRECIP AMOUNTS WILL RANGE FROM A TRACE TO 0.25" IN THE SAN
DIEGO AND RIVERSIDE COUNTY MTNS AS WELL AS AREAS WEST OF THE
MTNS. THE DESERTS WILL BE LUCKY TO GET ANY MEASURABLE PRECIP AND
THE SAN BERNARDINO MOUNTAINS WILL LIKELY GET ABOUT
0.2"-0.8"...GREATEST WEST OF THE CAJON PASS.
A REINFORCING MAJOR SHORTWAVE TROUGH MOVING INTO THE BASE OF THE
EXISTING TROUGH OVER THE WEST COAST WILL CONTINUE THE UNSETTLED
WEATHER AND BRING CHANCES FOR ADDITIONAL PRECIP FOR MONDAY AND
TUESDAY. MOST PRECIP WILL FALL IN THE SAN BERNARDINO MOUNTAINS
WHERE MON-TUE TOTALS WILL RANGE FROM ABOUT 0.2" EAST OF THE CAJON
PASS TO ABOUT 0.7" WEST OF THE CAJON PASS. ELSEWHERE, AMOUNTS WILL
RANGE FROM A TRACE TO 0.25", EXCEPT THE LOW DESERTS WHICH MAY GET
NO MEASURABLE PRECIP.
SNOW LEVELS WILL LIKELY REMAIN ABOVE 8,000 FT THROUGH FRIDAY
BEFORE DROPPING DOWN TO ABOUT 6,500-7,500 FT FOR SAT THROUGH NEXT
TUE. SNOWFALL ESTIMATES NEAR RESORT LEVELS ARE FOR A TRACE TO
ABOUT 4 INCHES BETWEEN SAT AND NEXT TUE.
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 WEDNESDAY 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 WEDNESDAY 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...SS
AVIATION/MARINE...KW
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