277
FXUS66 KSGX 291818
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
1018 AM PST MON DEC 29 2025
SYNOPSIS
DRY AND WARM WEATHER CONTINUES INTO TUESDAY WITH INCREASED SANTA
ANA WINDS ACROSS THE MOUNTAINS AND WESTERN VALLEYS. CLOUDIER SKIES
WILL ENTER THE REGION BY TUESDAY AS LOW PRESSURE SYSTEMS ACROSS
THE PACIFIC MOVE OVER OUR AREA. THIS WILL BRING CHANCES FOR
PERIODS OF RAIN AND SHOWERS FOR NEW YEAR'S EVE INTO THE WEEKEND.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
THIS MORNING...UNDER VARIABLE HIGH CLOUDS, SFC PRESSURE GRADIENTS -
WITH SOME SUPPORT FROM NORTHEAST WINDS ALOFT BELOW 18000 FT -
CONTINUE TO PRODUCE GUSTY SANTA ANA WINDS. IN THE LAST HOUR, SOME
OF THE WIND-PRONE AREAS HAVE REPORTED NORTHEAST TO EAST WINDS
GUSTING 45-55 MPH WITH LOCAL GUSTS OF 65+ MPH.
WITH AN UPPER-LEVEL HIGH PRESSURE RIDGE TO THE NORTH AND A CLOSED
UPPER LOW OVER THE SOCAL BIGHT RETROGRADING TO THE SOUTHWEST, DRY
AND WARM WEATHER WILL CONTINUE THROUGH TUESDAY. PERIODS OF GUSTY
SANTA ANA WINDS WILL ALSO CONTINUE THROUGH TUESDAY. NORTHEAST TO
EAST WINDS WILL CONTINUE TO GUST 45-55 MPH WITH LOCALLY HIGHER
GUSTS IN WINDS-PRONE AREAS. TUESDAY WILL LIKELY BE THE WARMEST DAY
WITH TEMPERATURES IN THE 70S TO NEAR 80 WEST OF THE MTNS. MOST
AREAS WILL BE NEAR TO AS MUCH AS 11 DEGREES ABOVE SEASONAL
AVERAGES. THE TEMPERATURE FORECAST FOR TUESDAY MAY BE COMPLICATED
BY HIGH CLOUDS MOVING IN FROM THE SOUTHWEST AND REDUCING DAYTIME
SOLAR HEATING BUT THE INCREASING HEIGHTS AND THICKNESSES WILL TEND
TO RAISE TEMPERATURES.
BY TUESDAY, THE RETROGRADING UPPER-LEVELCLOSED LOW JUST OFF THE
COAST WILL MERGE WITH THE CLOSED LOW ABOUT 1200 MILES SOUTHWEST OF
SAN DIEGO. BY WEDNESDAY THIS NEW LOW WILL BEGIN TO MOVE NORTHEAST
TOWARD SOCAL AS A LOW PRESSURE SYSTEM MOVES SOUTHWARD OUT OF THE
GULF OF AK. THESE SYSTEMS WILL BRING US PERIODS OF RAIN/SHOWERS
FROM LATE WED THROUGH THE WEEKEND. THIS WILL LIKELY OCCUR IN TWO
DISTINCT PHASES. THE FIRST PHASE WILL BE THE LOW TO THE SOUTHWEST
EJECTING TO THE NORTHEAST AND BECOMING AN OPEN WAVE OVER SOCAL ON
THU. DURING THIS PHASE, RELATIVELY WARM, MOIST AIR FROM THE
TROPICS WILL RESULT IN WIDESPREAD RAIN/SHOWERS BEFORE A DYNAMIC
RIDGE MOVES OVER THE REGION ON FRIDAY. THIS RIDGE COULD BRING A
BREAK IN THE PRECIPITATION UNTIL THE LOW FROM THE GULF OF AK
ARRIVES WITH COLDER AIR AND MORE RAIN/SHOWERS FOR SAT THROUGH
MONDAY. SNOW LEVELS WILL REMAIN ABOVE 8,000 FT THROUGH FRIDAY THEN
FALL TO AROUND 7,500 FT ON SAT AND 6,500 FT ON SUNDAY.
PRECIP AMOUNTS WILL BE GREATEST IN THE NORTHERN AREAS
(ORANGE AND SAN BERNARDINO COUNTIES) AND LESS IN SOUTHERN SAN
DIEGO COUNTY. CURRENT RAINFALL ESTIMATES ARE FOR TOTALS OF
1"-1.9" IN THE COASTAL AREAS, 1.1"-1.8" IN THE INLAND VALLEYS,
0.2"-0.6" IN THE LOW DESERTS, 0.25"-0.8" IN THE HIGH DESERT,
1.3"-3" IN THE SAN DIEGO AND RIVERSIDE COUNTY MTNS AND 1.5"-4.5"
IN THE SAN BERNARDINO MOUNTAINS. THE SNOW LEVEL WILL REMAIN ABOVE
8,000 FT THROUGH FRIDAY BEFORE LOWERING TO AROUND 6,500 FT ON
SATURDAY. MOST OF THE PRECIPITATION WILL LIKELY FALL BEFORE NEXT
WEEKEND SO SNOWFALL AMOUNTS AT RESORT LEVELS AND BELOW WILL BE
LIMITED.
AVIATION
291630Z...VFR CONDITIONS THROUGH THE TAF PERIOD WITH FEW TO
SCATTERED HIGH CLOUDS AROUND 25,000 FT MSL. GUSTY WINDS WILL
CONTINUE OUT OF THE NORTH TO NORTHEAST AND WILL GRADUALLY STRENGTHEN
INTO THE AFTERNOON WITH GUSTS OF 35-45 KTS FOR THE COASTAL MOUNTAIN
SLOPES AND MOUNTAIN PASSES AND 20-30 KT GUSTS STRETCHING BELOW
MOUNTAIN PASSES INTO INLAND VALLEYS. LOCALIZED AREAS OF REDUCED VIS
DUE TO BLDU IS POSSIBLE, ESPECIALLY NEAR THE MOUNTAINS. GUSTY
NORTHERLY WINDS BELOW CAJON PASS COULD PRODUCE CROSSWINDS ON
APPROACH/TAKEOFF WITHIN THE INLAND EMPIRE ALONG WITH 25-35 KTS OF
LOW LEVEL WIND SHEAR. WIDESPREAD MOD UP/DOWNDRAFTS EXPECTED,
ESPECIALLY NEAR MOUNTAINS AND MOUNTAIN PASSES. STRONG OFFSHORE WINDS
PREVAIL THROUGH TUESDAY MORNING.
MARINE
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...WIND ADVISORY UNTIL 1 PM PST TUESDAY FOR SAN BERNARDINO COUNTY
MOUNTAINS-SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE
INLAND EMPIRE-SAN DIEGO COUNTY MOUNTAINS-SAN DIEGO COUNTY
VALLEYS-SAN GORGONIO PASS NEAR BANNING-SANTA ANA MOUNTAINS
AND FOOTHILLS.
PZ...NONE.
PUBLIC...PG
AVIATION/MARINE...VILLAFANE
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