344
FXUS66 KSGX 280943
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
143 AM PST SUN DEC 28 2025
SYNOPSIS
WARMER AND DRIER SUNDAY THROUGH TUESDAY WITH PERIODS OF MODERATE
GUSTY SANTA ANA WINDS. A LOW PRESSURE SYSTEM FROM THE SOUTHWEST
WILL LIKELY BRING A RETURN OF PRECIPITATION FOR WEDNESDAY THROUGH
NEXT WEEKEND, THOUGH EXACT TIMING AND PRECIPITATION AMOUNTS ARE
STILL UNCERTAIN.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
TODAY THROUGH TOMORROW...
CURRENTLY THIS MORNING, THERE ARE A FEW OF THE INLAND AREAS
SHELTERED BY WIND WHICH ARE EXPERIENCING SOME PATCHY FOG, SUCH AS
RAMONA. THIS IS GENERALLY VERY ISOLATED IN NATURE, ALTHOUGH THE
VISIBILITIES HAVE DROPPED DOWN TO A QUARTER OF A MILE, SO TAKE
CAUTION OF THIS IF COMMUTING WITHIN THESE AREAS. UNDER HIGH PRESSURE
CONDITIONS AND CLEAR SKIES, RADIATIONAL COOLING HAS ALLOWED FOR
TEMPERATURES TO COOL OFF QUITE SUBSTANTIALLY THROUGHOUT THE NIGHT,
WITH SOME OF THE COASTAL AREAS FALLING INTO THE 40S, AND 30S WITHIN
THE INLAND VALLEYS. THIS WILL GIVE WAY TO A NOTABLY WARMER DAY AS
WEAK OFFSHORE AND DOWNSLOPING WINDS HELP TO ADIABATICALLY WARM UP
THE LOWER ELEVATIONS, WITH WIDESPREAD UPPER 60S AND LOW 70S FOR THE
COASTAL AND INLAND AREAS. THE HIGHER ELEVATIONS WILL STILL BE A
LITTLE ON THE CHILLY SIDE, ESPECIALLY FOR THE HIGH DESERTS WITH THE
COLDER AIR ADVECTION BLOWING IN FROM THE NORTH.
A WELL-PRONOUNCED RIDGE OVER THE ENTIRE WEST COAST WILL CONTINUE TO
EXPAND EASTWARD, WITH AN AREA OF HIGH PRESSURE MOVING IN OVER THE
GREAT BASIN TO ESTABLISH MARGINAL SANTA ANA CONDITIONS TO BUILD IN
ACROSS THE REGION. GUSTY OFFSHORE WINDS OUT OF THE NORTHEAST,
ESPECIALLY ACROSS THE HIGHER TERRAIN, WILL BEGIN TO STRENGTHEN LATER
TONIGHT THROUGH TOMORROW. THESE WINDS AT THIS TIME LOOK TO REMAIN
BELOW HIGH WIND CRITERIA FOR MOST OF THE WIND-PRONE LOCATIONS AND
MARGINAL AT BEST ACROSS THE SAN BERNARDINO MOUNTAINS, HOWEVER WIND
ADVISORY CRITERIA LOOKS TO BE MORE LIKELY, ESPECIALLY FOR THE
PASSES, WITH CAJON PASS IN PARTICULAR. FOR THESE LOCATIONS, WIND
GUSTS MAY OCCASIONALLY APPROACH 60 MPH, AS WELL AS OTHER HIGHER
TERRAIN PRONE TO STRONG WINDS. STRONGEST WIND GUSTS WILL PEAK LATER
TONIGHT AND GOING INTO MONDAY MORNING, AND THEN THE STRONGER GUSTS
WILL FILTER IN FURTHER SOUTHWARD BY LATER IN THE DAY, AND THEN
GRADUALLY WEAKEN GOING INTO TUESDAY. RH VALUES WILL DROP INTO THE
TEENS FOR A FEW LOCATIONS ON MONDAY AFTERNOON, ALTHOUGH GIVEN RECENT
RAINFALLS WITH AN ABUNDANCE IN ANTECEDENT SOIL MOISTURE, FIRE
WEATHER CONDITIONS ARE NOT ANTICIPATED TO BE OF ANY CONCERN. THE
MAIN CONCERN WITH THESE WINDS AND THE RECENT RAINFALLS WILL BE THE
POSSIBILITY OF TREES BEING EASILY UPROOTED FOR THE SAN BERNARDINO
MOUNTAINS. THERE WILL BE A LESSER THREAT OF THIS GOING INTO THE
MOUNTAINS OF RIVERSIDE AND SAN DIEGO COUNTIES, SINCE LESS RAIN WAS
RECEIVED ACROSS THESE AREAS.
TUESDAY THROUGH SATURDAY...
THESE STRONG AND GUSTY WINDS WILL CONTINUE INTO TUESDAY AND THEN
BEGIN TO SUBSIDE THEREAFTER AS THE RIDGE BEGINS TO BREAK DOWN, AND
ALLOWS FOR AN UPPER LEVEL LOW (WHICH WILL BECOME CUT OFF WELL TO THE
SOUTHWEST OF THE REGION OVER THE PACIFIC WATERS) TO BEGIN TO
PROPAGATE BACK UP TOWARDS THE NORTHEAST AS A LONGWAVE TROUGH
UPSTREAM ADVANCING TOWARDS THE REGION ABSORBS THE ENERGY OF THIS U/L
LOW AND BRINGS IT BACK TOWARDS SOCAL. THIS WILL LEAD TO INCREASING
CLOUDS AND THE CHANCE OF RAIN, ALONG WITH THE RETURN OF A GRADUAL
COOLDOWN GOING INTO THE LATER HALF OF THE WEEK. THE MOISTURE FROM
THIS FEATURE, IN COMBINATION WITH THE 500 MB SHORTWAVE TROUGH MOVING
IN AS THE "KICKER" MAY ALLOW FOR SOME MORE DECENT RAINFALLS AGAIN,
DEPENDING ON HOW THIS SETS UP AND WHERE THE U/L LOW ENDS UP
TRACKING. SOME OF THE MODELS ARE ALSO SHOWING A WEAK SIGNAL OF AN
ATMOSPHERIC RIVER ASSOCIATED WITH THIS, WHICH MAY HELP TO NUDGE UP
RAINFALL AMOUNTS. THE DETERMINISTIC MODELS ARE BEGINNING TO TIGHTEN
UP IN TERMS OF AGREEMENT WITH THE PROGRESSION OF THIS U/L LOW AS IT
MOVES UP FROM THE SOUTH AND NEARS SOCAL, WHICH PLACES THE CENTER OF
THE LOW ROUGHLY AROUND 500 MILES WEST OF SAN DIEGO OVER THE E PAC
WATERS FROM WEDNESDAY NIGHT GOING INTO THURSDAY MORNING. THE FIRST
INITIAL WAVE WITH BANDS OF PRECIPITATION SHOULD REACH THE CWA
SOMETIME DURING THE AFTERNOON ON WEDNESDAY, WITH THE MORE
PERSISTENT AND HEAVIER PRECIP NOT MOVING IN UNTIL LATER IN THE
EVENING INTO THURSDAY MORNING. MODELS ARE STILL STRUGGLING
THEREAFTER WITH THE TRACK, WITH THE ECMWF HAVING THE LOW CENTER NEARING
PT CONCEPTION, WHILE THE GFS STILL KEEPS THE LOW CENTERED FURTHER
OFFSHORE, AND THE CANADIAN HAVING IT EVOLVE INTO AN OPEN WAVE.
THIS WILL CONTINUE TO BE EVALUATED IN THE UPCOMING DAYS, BUT THERE
IS GROWING CONFIDENCE THAT INCLEMENT WEATHER WILL IMPACT THE
REGION RIGHT AROUND THE TURN OF THE NEW YEAR. AS THE MAJOR
SHORTWAVE TROUGH ACTING AS THE KICKER CONTINUES TO PROPAGATE
TOWARDS CALIFORNIA, IT WILL HELP TO INCREASE PRECIP CHANCES GOING
INTO SATURDAY, AND LIKELY THROUGH NEXT WEEKEND.
AVIATION
280930Z...VFR CONDITION ARE EXPECTED THROUGH THE TAF PERIOD WITH FEW-
SCT HIGH CIRRUS AOA 25,000FT AND LOCALIZED AREAS OF GROUND FG WITH
VIS BELOW 1SM THROUGH SUNRISE, GENERALLY IN THE VALLEYS. NORTH-
NORTHEASTERLY OFFSHORE WINDS PICK UP AFTER 12Z, GRADUALLY
STRENGTHENING THIS AFTERNOON/EVENING. WIND GUSTS OF 25-30KTS
EXPECTED FOR THE COASTAL SLOPES OF THE MOUNTAINS AND MOUNTAIN PASSES
FROM 12-18Z, SPREADING BELOW MOUNTAIN PASSES AND INTO THE INLAND
VALLEYS AFTER 18Z. WHILE GUSTS MAY NOT SURFACE AT TERMINALS LIKE
KONT OR KSBD UNTIL LATE TONIGHT OR MONDAY MORNING, GUSTY NORTHERLY
WINDS BELOW CAJON PASS COULD PRODUCE CROSSWINDS ON APPROACH/TAKEOFF
WITHIN THE INLAND EMPIRE SUNDAY AFTERNOON. LLWS MAY BE POSSIBLE,
ESPECIALLY LATE TONIGHT, FOR INLAND EMPIRE AIRPORTS. GUSTS
STRENGTHEN TO 35-45 KTS FOR THE COASTAL MOUNTAIN SLOPES AND PASSES
AFTER 00Z MONDAY WITH MOD UP/DOWNDRAFTS EXPECTED. STRONG OFFSHORE
WINDS PREVAIL INTO MONDAY EVENING.
MARINE
NO HAZARDOUS MARINE WEATHER CONDITIONS EXPECTED THROUGH FRIDAY.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...HIGH WIND WATCH FROM THIS EVENING THROUGH TUESDAY AFTERNOON FOR
SAN BERNARDINO COUNTY MOUNTAINS-SAN BERNARDINO AND
RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-SAN GORGONIO
PASS NEAR BANNING-SANTA ANA MOUNTAINS AND FOOTHILLS.
HIGH WIND WATCH FROM LATE TONIGHT THROUGH TUESDAY AFTERNOON FOR
SAN DIEGO COUNTY MOUNTAINS-SAN DIEGO COUNTY VALLEYS.
PZ...NONE.
PUBLIC...STEWEY
AVIATION/MARINE...ZUBER
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