496
FXUS66 KSGX 172126
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
126 PM PST TUE DEC 17 2024
SYNOPSIS
ABOVE NORMAL TEMPERATURES WILL CONTINUE OVER THE NEXT FEW DAYS
WITH GUSTY SANTA ANA WINDS FROM THE FOOTHILLS TO THE WESTERN
VALLEYS TODAY AND WEDNESDAY. A TROUGHING REGIME WILL SET UP OFF
THE WEST COAST LATER THIS WEEK, BRINGING A DEEPER MARINE LAYER,
TEMPERATURES A BIT COOLER AND LIGHTER WINDS. THIS TROUGHING
PATTERN MAY STRENGTHEN ENOUGH TO BRING LIGHT PRECIPITATION TO THE
REGION EARLY NEXT WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
THIN CIRRUS CLOUDS CONTINUE TO MOVE IN FROM THE NORTH THIS
AFTERNOON. A 1032 MB AREA OF HIGH PRESSURE HAS SET UP ACROSS
NORTHERN NEVADA, HELPING PROMPT NORTHERLY WINDS FROM THE DESERT TO
HEAD TOWARD THE COAST IN THE FORM OF SANTA ANA WINDS. CURRENTLY
WINDS ARE MAINLY CONFINED TO NORTHERN PASSES AND FOOTHILLS,
LOCALLY MOVING SOUTHWARD INTO THE INLAND EMPIRE. WE CAN EXPECT
THESE WINDS TO STRENGTHEN AND BECOME MORE WIDESPREAD OVERNIGHT.
HIGHEST WINDS WILL BE IN THE COASTAL FACING PASSES WITH GUSTS
LOCALLY OVER 50 MPH IN THE SANTA ANA MOUNTAINS AND SAN BERNARDINO
MOUNTAINS, LOCALLY OVER 40 MPH IN SAN DIEGO COUNTY PER LATEST
WRF/NBM MODEL GUIDANCE.
AS THE WINDS BEGIN TO BECOME MORE LOCALIZED ON WEDNESDAY, THE
OFFSHORE WIND PATTERN WILL LEAD TO INCREASED TEMPERATURES OVER
THE REGION AS WELL. HIGH TEMPERATURES WILL BE UP TO LOCALLY 20
DEGREES ABOVE NORMAL FOR INLAND VALLEYS WEST OF THE MOUNTAINS BY
THIS TIME WITH MANY AREAS REACHING INTO THE LOW TO MID 80S. PLACES
LIKE EL CAJON, LAKE ELSINORE AND CHINO HAVE ABOUT A 30-50% CHANCE
OF REACHING THE 85 DEGREE MARK ON WEDNESDAY AFTERNOON PER LATEST
NBM PROBABILITIES. GREATER ONSHORE FLOW WILL OCCUR BY THURSDAY
INTO FRIDAY, HELPING DEEPEN THE MARINE LAYER KNOCK TEMPERATURES
DOWN SOME FOR THOSE WEST OF THE MOUNTAINS. THIS WILL BRING A
BETTER CHANCE OF LOW CLOUDS AND PATCHY FOG ACROSS THE COASTAL
AREAS EACH NIGHT AND MORNING.
BY THE WEEKEND, A TROUGHING PATTERN BECOMES MORE APPARENT OVER THE
WEST COAST AS WAVES OF PRECIPITATION ARE EXPECTED FOR PARTS OF
NORTHERN CALIFORNIA. THE JET STREAM MAY BECOME AMPLIFIED ENOUGH TO
BRING LIGHT PRECIPITATION TO PARTS OF SOCAL NEAR THE CHRISTMAS
EVE TIME FRAME AS SOME MODEL ENSEMBLE GUIDANCE SUGGESTS. NBM POPS
LEFT IN AS CHANCES FOR MEASURABLE RAINFALL LOOK SMALL FOR NOW
(10-30%), THOUGH ENSEMBLE CLUSTER ANALYSIS PAINTS A MORE DRIER
RIDGING PATTERN OVERALL. THIS LEADS TO A CONTINUED HIGH
UNCERTAINTY FORECAST, SO PLEASE KEEP UP WITH THE LATEST DETAILS AS
WE HEAD CLOSER TO THE CHRISTMAS HOLIDAY.
AVIATION
172100Z....COASTS/VALLEYS...VARIABLE HIGH CLOUDS THROUGH TOMORROW.
STRONGER OFFSHORE FLOW OVERNIGHT AND LLWS FOR AREAS WEST OF THE
MOUNTAINS VCNTY KONT, KSBD AND KSNA UNTIL 00-05Z. LOW CLOUDS DEVELOP
OFFSHORE TONIGHT WITH BASES NEAR 500-600FT MSL, BUT ARE UNLIKELY TO
MOVE INLAND WITH ONLY A 5-10% CHANCE OF A CIG AT KSAN FOR WEDNESDAY
MORNING.
MOUNTAINS/DESERTS
HIGH CLOUDS THROUGH WEDNESDAY GENERALLY
ABOVE 20,000FT MSL. NORTHEAST TO EAST WINDS GUSTING 25-35 KTS
WITH WEAK TO MODERATE UP/DOWNDRAFTS OVER THE MOUNTAINS. BLDU
POSSIBLE AND MAY BRIEFLY REDUCE VIS DOWN TO 3SM. LOCALLY STRONGER
SURFACE WINDS THROUGH MOUNTAIN PASSES. LIGHTER WINDS AFTER 18Z
WEDNESDAY.
MARINE
NO HAZARDOUS MARINE WEATHER CONDITIONS ARE EXPECTED THROUGH SATURDAY.
FIRE WEATHER...
GUSTY NORTHERLY SANTA ANA WINDS WILL CONTINUE TO SPREAD INTO
FOOTHILLS AND VALLEYS OF ORANGE AND THE INLAND EMPIRE, A BIT LATER
INTO PARTS OF SAN DIEGO COUNTY. THE WINDS WILL CONTINUE INTO
WEDNESDAY MORNING, THEN GRADUALLY WEAKEN FOR WEDNESDAY AFTERNOON
AND EVENING.
THE STRONGER GUSTS ALONG AND BELOW THE COASTAL SLOPES OF THE SAN
BERNARDINO COUNTY MOUNTAINS AND ALONG AND BELOW THE COASTAL SLOPES
OF THE SANTA ANA MOUNTAINS ARE EXPECTED TO REACH 40 TO 50 MPH,
WITH THE STRONGER GUSTS ALONG AND BELOW THE COASTAL SLOPES OF THE
MOUNTAINS IN RIVERSIDE AND SAN DIEGO COUNTIES TO 30 TO 40 MPH.
THE LOWEST HUMIDITY ON WEDNESDAY FOR THE VALLEYS, INLAND COASTAL
AREAS, AND COASTAL SLOPES OF THE MOUNTAINS WILL FALL TO 10 TO 15
PERCENT. ONLY ISOLATED AREAS IN EITHER TIME OR SPACE MIGHT
BRIEFLY REACH RED FLAG CRITERIA FOR WEDNESDAY AFTERNOON WITH THE
MOST LIKELY LOCATIONS FOR THAT TO OCCUR BEING IN THE INLAND
EMPIRE BELOW THE CAJON PASS AND BANNING PASS.
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...APR
AVIATION/MARINE...ZUBER
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