297
FXUS66 KSGX 270401
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
901 PM PDT WED MAR 26 2025
SYNOPSIS
COOL WITH A DEEP MARINE AND PATCHY DRIZZLE AT TIMES THROUGH THE
WEEKEND. THERE WILL BE GUSTY WEST WINDS FOR THURSDAY AFTERNOON
THROUGH LATE FRIDAY NIGHT WITH THE STRONGER GUSTS FOR THE
MOUNTAINS AND DESERTS MOSTLY 45 TO 55 MPH. COOLER THAN AVERAGE
CONDITIONS WILL CONTINUE INTO NEXT WEEK WITH CHANCES FOR
PRECIPITATION INCREASING TO AROUND 50 PERCENT LATE NEXT WEDNESDAY
AND THURSDAY THURSDAY. CONFIDENCE IS LOWER WITH THE TIMING AND
POTENTIAL AMOUNTS. DAILY CHANCES FOR ONE INCH OR MORE OF RAINFALL
ARE 20 PERCENT OR LESS FOR THE TYPICALLY WETTER LOCATIONS.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
EVENING UPDATE...
MARINE LAYER LOW CLOUDS NEVER LEFT TODAY AND EVEN REMAIN SOCKED IN
THROUGH THE MOUNTAIN PASSES. THE 00Z KNKX SOUNDING SHOWS A MARINE
INVERSION BASED NEAR 3700 FT MSL WITH A SATURATED LAYER AROUND
1600 FT THICK. PATCHY LIGHT DRIZZLE COULD OCCUR AGAIN TONIGHT FROM
THE DEEP MARINE LAYER, THOUGH THE POTENTIAL FOR ANY ACCUMULATING
PRECIPITATION IS LESS THAN 5% AS WE LOSE LARGE-SCALE LIFT FROM THE
DEPARTING SHORT WAVE TROUGH AND WEAK TRANSITORY RIDGING BEGINS
MOVE IN FROM THE WEST. HREF SHOWS BETTER MUCH BETTER CLEARING ON
THURSDAY, WHICH MIGHT ACTUALLY ALLOW FOR SOME WARMING WEST OF THE
MOUNTAINS DESPITE ANOTHER SHORT WAVE TROUGH ROTATING INTO THE WEST
COAST.
PREVIOUS DISCUSSION...
THE MAJOR SHORTWAVE TROUGH WILL BEGIN TO DEEPEN AND ALLOW FOR
STRONGER AND GUSTY WINDS TO PICK UP AHEAD OF IT FOR THE MOUNTAINS
AND DESERTS. THERE COULD ALSO BE AREAS OF BLOWING DUST/SAND POSSIBLE
WITHIN THE COACHELLA VALLEY. FOR THIS REASON, THE AIR QUALITY ALERT
IS IN EFFECT THROUGH NOON ON FRIDAY, AND MAY NEED TO BE EXTENDED
DEPENDING ON THE WINDS.
THE PATTERN WILL REMAIN UNCHANGED THROUGH THE WEEKEND WITH THE
LONGWAVE TROUGH UPSTREAM OVER THE NORTHWESTERN REGION. IT WILL
BECOME MORE ZONAL GOING INTO THE EARLY PART OF NEXT WEEK, WHICH WILL
ALLOW FOR COOLER TEMPERATURES TO STAY LOCKED IN OVER THE REGION AND
THE HIGHER TERRAIN AND DESERTS (BASICALLY FOR THE AREAS PRONE TO
INCREASED WIND FLOW, SUCH AS MOUNTAIN CANYONS AND PASSES) PRETTY
MUCH EACH DAY. THERE WILL ALSO BE THE TAIL END OF A SYSTEM MOVING
THROUGH BY LATER IN THE WEEKEND WHICH WILL PASS THROUGH THE CWA,
AND MAY ALLOW FOR A FEW LIGHT SHOWERS ON SUNDAY EVENING AS IT
PASSES THROUGH. OTHERWISE, THE MAIN TAKEAWAY WILL BE COOLER (MORE
SEASONAL) TEMPERATURES, MOSTLY CLOUDY TO OVERCAST SKIES FOR THE
COASTAL AND INLAND AREAS, AS WELL AS ELEVATED WINDS FOR THE
MOUNTAINS AND DESERTS, WILL CONTINUE TO BE THE STORY THROUGH THE
EARLY PART OF NEXT WEEK.
AVIATION
270315Z...COAST/VALLEYS/FOOTHILLS...LOW CLOUDS WILL PERSIST ACROSS
THE COASTAL BASIN. BASES VARY BETWEEN 2500-3500 FEET MSL WITH TOPS
TO 4500 FEET, BUT ARE EXPECTED TO LOWER BELOW 3000 FT MSL EARLY THU
MORNING. VIS REDUCED 3-5SM OVER HIGHER TERRAIN INLAND, WITH PARTIAL
OBSCURATIONS OF 0-2SM IN FOOTHILLS. SCATTER OUT THURSDAY LIKELY TO
BE ONLY PARTIAL AFTER 18Z, ESPECIALLY FOR COASTAL AREAS. LOW CLOUDS
BECOMING WIDESPREAD AND SPREADING THROUGH MOST OF THE COASTAL BASIN
AGAIN AFTER 00Z FRI, BASES 2000-3000 FT MSL.
HIGHER MOUNTAINS/DESERTS...SCT HIGH CLOUDS ABOVE 20000 FEET MSL.
WESTERLY WINDS OVER THE RIDGES OVER NIGHT WILL STRENGTHEN AGAIN AND
SPREAD THROUGH THE LEE SLOPES INTO DESERTS AFTER 19Z THU, WITH GUSTS
30-50 KTS. AREAS OF MODERATE UP/DOWNDRAFTS IN LEE OF MOUNTAINS.
MARINE
NORTHWEST WINDS STRENGTHEN FRIDAY MORNING IN THE OUTER COASTAL
WATERS, GUSTING TO 25 KNOTS FRIDAY AFTERNOON INTO SATURDAY MORNING,
STRONGEST NEAR SAN CLEMENTE ISLAND. CHOPPY SEAS AND HAZARDOUS
BOATING CONDITIONS ARE LIKELY. OTHERWISE, NO HAZARDOUS MARINE
CONDITIONS ARE EXPECTED BEFORE AND AFTER THAT PERIOD.
BEACHES
ELEVATED SURF 4-6 FEET, WITH LOCAL SETS TO 8 FEET ON WEST-FACING
BEACHES, AND HIGH RIP CURRENT RISK EXPECTED FRIDAY AND SATURDAY.
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...SS/STEWEY
AVIATION/MARINE/BEACHES...CSP
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