456
FXUS66 KSGX 121101
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
401 AM PDT SUN APR 12 2026
SYNOPSIS
A LOW PRESSURE SYSTEM WILL IMPACT THE REGION THROUGH MONDAY,
BRINGING MODERATE RAINFALL, HIGH ELEVATION SNOW AND A SLIGHT
CHANCE OF THUNDERSTORMS WEST OF THE MOUNTAINS. THIS LOW PRESSURE
SYSTEM MAY LINGER OVER THE AREA INTO MONDAY, BRINGING ADDITIONAL
LIGHT SHOWERS. DRIER AND SLIGHTLY WARMER WEATHER IS EXPECTED BY
THE MIDDLE AND END OF NEXT WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
TODAY THROUGH TOMORROW NIGHT...
AT THIS HOUR, THERE ARE SOME VERY ISOLATED PRE-FRONTAL SHOWERS
BEGINNING TO DEVELOP WITHIN THE INNER SOCAL BIGHT, AND SOME OF THESE
MAY MAKE IT ON SHORE FOR JUST A FEW LIGHT SHOWERS THIS MORNING
THROUGH EARLY AFTERNOON BEFORE ARRIVAL OF THE ASSOCIATED COLD
FRONTAL BOUNDARY WITH THIS SECONDARY LOW PRESSURE SYSTEM PROPAGATING
OVERHEAD THROUGH TOMORROW. THIS WILL ALLOW FOR THERE TO BE SOME
LIGHT TO MODERATE SHOWERS TO DEVELOP ALONG THE LEADING EDGE OF THIS
BOUNDARY AS IT MAKES ITS WAY THROUGH THE AREA BY LATER THIS
AFTERNOON, WHICH HIGH RES MODELS PUT THE TIMING OF THE FRONT TO
BEGIN MOVING THROUGH ORANGE COUNTY BY AROUND 11 TO NOON. THERE IS
ALSO JUST ENOUGH INSTABILITY THAT THERE COULD BE A HEAVIER
SHOWERS/THUNDERSTORMS EMBEDDED WITHIN THIS LINE OF SHOWERS AS IT
MOVES THROUGH THE CWA DURING THE AFTERNOON HOURS. THE TIGHTENING OF
THE SURFACE PRESSURE GRADIENT IS ALSO GOING TO ALLOW FOR SOME STRONG
AND GUSTY WINDS BY LATER THIS AFTERNOON ACROSS THE HIGHER TERRAIN,
AND ESPECIALLY WITHIN THE AREAS PRONE TO GAP FLOW, AND ACROSS THE
RIDGES AND SLOPES. THERE MAY BE SOME GUSTS THAT PEAK OVER CRITERIA
ON OCCASION, ALTHOUGH THE MAJORITY OF PEAK WINDS FOR HIGHER
ELEVATIONS SHOULD REMAIN CLOSER TO THE 45 TO 50 MPH RANGE, WHICH IS
WHY A WIND ADVISORY HAS NOT BEEN ISSUED. NONETHELESS, IT IS GOING TO
BE GUSTY AND CHILLY, WITH HIGHS TODAY GENERALLY RUNNING AROUND 5 TO
15 DEGREES BELOW THE SEASONAL AVERAGE FOR THIS TIME OF YEAR, FOR
MOST LOCATIONS.
THIS LOW WILL CONTINUE TO TRACK THROUGH THE AREA GOING INTO
TOMORROW, WITH ALSO A WEAK PERTURBATION AT THE 700-500 MB LEVEL
MOVING OVER THE REGION DURING THE EARLY MORNING HOURS, WHICH MAY
ALLOW FOR THERE TO BE SOME PERSISTENT LIGHT SHOWERS REMAINING
THROUGH THE MORNING HOURS TOMORROW BEFORE TAPERING OFF TOWARDS THE
AFTERNOON. HIGHS FOR TOMORROW WILL BE SIMILAR TO TODAY, AND STILL
QUITE CHILLY, PERHAPS EVEN A FEW DEGREES COOLER FOR A FEW LOCATIONS
AS THERE WILL BE MUCH STRONGER COLD AIR ADVECTION MOVING IN BEHIND
THIS EXITING TROUGH. SNOW LEVELS WILL ALSO DROP DOWN TO AROUND 5000-
5500 FEET BY LATER TONIGHT INTO EARLY TOMORROW, AND THERE COULD BE
SOME OF THE URBANIZED AREAS ABOVE 5000 FEET PICKING UP SEVERAL
INCHES OF NEW SNOW AS A RESULT. STRONG AND GUSTY WESTERLY WINDS WILL
CONTINUE INTO TOMORROW AFTER WEAK DECOUPLING OVERNIGHT, ALTHOUGH NOT
BE AS STRONG AND WILL CONTINUE TO DIMINISH THROUGHOUT THE DAY. BY
THE TIME THIS LOW HAS EXITED, THERE COULD BE SOME OF THE COASTAL
AREAS PICKING UP AROUND THREE QUARTERS OF AN INCH, TO OVER A HALF AN
INCH FOR THE INLAND AREAS, AND SOME OF THE COASTAL SLOPES OF THE
MOUNTAINS MAY RECEIVE UP TO AROUND ONE TO ONE AND ONE HALF INCHES OF
RAINFALL, WITH LOCALLY UP TO 2 INCHES POSSIBLE FOR THE SOUTHERN-
FACING SLOPES OF THE SAN BERNARDINO MOUNTAINS.
TUESDAY THROUGH NEXT WEEKEND...
HIGH PRESSURE WILL BE BUILDING IN BACK OVER THE REGION FROM TUESDAY
INTO WEDNESDAY AS SOME WEAK RIDGING ALOFT IS USHERED IN BEHIND THE
EXITING TROUGH, WHICH WILL HELP TO ALLOW TEMPERATURES TO REBOUND
QUITE NICELY FOR BOTH DAYS, AND BACK TO NEAR AVERAGE TEMPERATURES,
ESPECIALLY BY WEDNESDAY. THE OVERALL ENSEMBLE PATTERN LOOKS HAS HAD
LITTLE CHANGE TO PREVIOUS RUNS, SHOWING SOLUTIONS OF MORE TROUGHING
BY LATER IN THE WORK WEEK, WHICH COULD INFLUENCE THE AREA WITH SOME
PRECIPITATION, INCREASED WINDS AGAIN, ALONG WITH A REINFORCEMENT OF
COOLER AIR ON THURSDAY. DEPENDING ON THE TRACK OF THE DEEPENING
MAJOR SHORTWAVE TROUGH, AND MOREOVER IF IT TAKES A MORE "INSIDE
SLIDER" TRACK WILL DETERMINE WHETHER OR NOT THIS WILL BE MORE OF
JUST A WIND PRODUCER, WITH POSSIBLE OFFSHORE WINDS. A RETURN OF WEAK
RIDGING OVER THE REGION FOR THIS UPCOMING WEEKEND WILL HELP TO DRY
THINGS OUT AND WARM THINGS UP CONSIDERABLY BY SATURDAY.
AVIATION
121100Z...COASTS/VALLEYS...INCREASING CLOUDS BASED 3-6 KFT MSL TO
THIS MORNING THROUGHOUT THE COASTAL AND INLAND BASIN. ISO -SHRA THIS
MORNING WILL BECOME MORE NUMEROUS OVERNIGHT INTO EARLY MONDAY.
MOSTLY VFR VIS/CIGS OVERNIGHT UNTIL MAIN FRONTAL BAND PUSHES INTO
THE REGION FROM THE NORTHWEST, REACHING ORANGE COUNTY AROUND 16-18Z.
THIS BAND IS EXPECTED TO BRING A FEW HOURS OF SHRA/RA AND PERIODS OF
MVFR VIS/CIGS (1-3 KFT BASES, 4-6SM) WITH THE OCCASIONAL +SHRA/+RA,
YIELDING BRIEF IFR CIGS/VIS. THE FRONT REACHES SD CO. AROUND 19Z,
SWEEPING THROUGH THE COUNTY DURING THE AFTERNOON AND YIELDING
SIMILAR CONDITIONS. AFTER FROPA, WINDS SWITCH FROM SW TO W.
FORECAST WINDOW FOR RA/+RA AND IFR CIGS/VIS:
KSNA...17-20Z SUN
KONT...17-21Z SUN
KSBD...17-22Z SUN
KCRQ...20-23Z SUN
KSAN...20-24Z SUN
MOUNTAINS/DESERTS
WEST TO SOUTHWEST WINDS GUSTS 35-50 KT TO
PERSIST THROUGHOUT THE TAF PERIOD IN MOUNTAIN PASSES, ALONG DESERTS
SLOPES AND LOCALLY INTO THE DESERTS. LOCAL AREAS BLDU (VIS 3-5SM)
EXPECTED. MODERATE UP/DOWNDRAFTS IN LEE OF MTNS. VIS DOWN TO 0-5SM
IN MTNS WITH FG WHERE CLOUDS AND TERRAIN MEET; SHSN MAY REDUCE VIS
LOCALLY ABOVE 6500 FT MSL.
MARINE
THERE IS A SLIGHT (~10%) CHANCE OF THUNDERSTORMS LATER THIS
AFTERNOON. ADDITIONALLY THERE WILL BE PERIODS OF INCREASED NORTHWEST
WINDS WITH GUSTS 15 TO 20 KT AND CHOPPY SEAS THROUGHOUT THE DAY.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
PUBLIC...STEWEY
AVIATION/MARINE...STEWEY
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