807
FXUS66 KSGX 170445
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
945 PM PDT FRI MAY 16 2025
SYNOPSIS
COOLER CONDITIONS WITH INCREASED WINDS AND CLOUD COVERAGE EXPECTED
OVER THE WEEKEND. LOW CLOUDS ARE EXPECTED TO FILL IN MUCH OF THE
COASTAL BASIN EACH NIGHT AND MORNING. THERE ARE CHANCES OF LIGHT
RAIN AND DRIZZLE WEST OF THE MOUNTAINS TONIGHT INTO SATURDAY AND
SATURDAY NIGHT INTO SUNDAY. WARMER CONDITIONS WITH A SHALLOWER
MARINE LAYER IS EXPECTED FOR NEXT WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
UPDATE: SATELLITE IMAGERY REVEALS THAT LOW CLOUDS HAVE BEGUN TO FILL
BACK IN ACROSS MOST OF THE COASTAL AND SOME OF THE INLAND AREAS OF
SAN DIEGO AND ORANGE COUNTIES. THERE COULD BE SOME DRIZZLE POSSIBLE
BY LATER THIS EVENING AND THROUGH THE EARLY MORNING HOURS TOMORROW.
THE LATEST HRRR SHOWS THAT THERE COULD BE A FEW SHOWERS DEVELOPING
BY LATER IN THE EVENING TOMORROW, MOSTLY FOR THE FOOTHILLS AND WEST-
FACING SLOPES, AND LIKELY ONLY VERY LIGHT WITH ACCUMULATIONS OF NO
MORE THAN 0.10 OF AN INCH TOTAL FOR MOST AREAS THROUGH MIDNIGHT
TOMORROW. BY SUNDAY MORNING, MOST PRECIP SHOULD COME TO AN END, WITH
PERHAPS ONLY A COUPLE LINGERING SHOWERS OVER THE COASTAL AND INLAND
AREAS OF SAN DIEGO COUNTY.
WINDS HAVE ALSO BEGUN TO INCREASE FOR THE MOUNTAINS AND DESERTS,
PROMPTING THE ISSUANCE OF AND AIR QUALITY ALERT BY SOUTH COAST AQMD
FOR THE COACHELLA VALLEY, DUE TO BLOWING DUST. THIS IS CURRENTLY IN
EFFECT UNTIL 9 AM SUNDAY. THESE WINDS WILL BEGIN TO SUBSIDE BY LATER
IN THE EVENING TOMORROW, AND LIKELY NOT NEED TO ISSUE AN EXTENSION
TO THE WIND ADVISORY ALREADY IN EFFECT UNTIL 2 AM SUNDAY MORNING.
FROM THERE, DRIER AND SLIGHTLY WARMER TEMPERATURES ON SUNDAY WILL BE
FOLLOWED BY A MUCH MORE DRASTIC WARMUP GOING INTO THE MIDDLE OF NEXT
WEEK AS A STRONG RIDGE BEGINS TO BUILD BACK IN OVER THE REGION.
(PREVIOUS DISCUSSION SUBMITTED AT 145 PM):
A TROUGH OF LOW PRESSURE WILL START TO DIG INTO THE PACIFIC
NORTHWEST LATER TONIGHT. CROSS SECTIONS OF OUR LOCAL WRF ARE
INDICATING A FAIRLY DEEP SATURATED LAYER FOR TONIGHT INTO SATURDAY
MORNING. CURRENT INDICATIONS ARE THIS LAYER WILL BE SATURATED ENOUGH
TO PRODUCE AREAS OF DRIZZLE OR LIGHT RAIN WEST OF THE MOUNTAINS AND
ON MOUNTAIN SLOPES DURING THAT TIME. MINIMAL ACCUMULATIONS ARE
EXPECTED WITH CHANCES OF RAINFALL TOTALS REACHING OR EXCEEDING 0.10"
AT 5 PERCENT OR LESS.
AS THE LOW PRESSURE SYSTEM BEGINS TO DIG SOUTH INTO THE GREAT BASIN
SATURDAY AFTERNOON AND EVENING, RAIN CHANCES INCREASE ESPECIALLY FOR
SAN DIEGO COUNTY. ANY RAINFALL IS EXPECTED TO BE LIGHT, BUT MORE
WIDESPREAD ACROSS THE COASTAL BASIN COMPARED TO WHAT IS EXPECTED
TONIGHT INTO SATURDAY MORNING. IT'S UNLIKELY RAINFALL TOTALS WILL
EXCEED 0.20" FOR THE COAST AND VALLEYS AND 0.40" FOR THE COASTAL
MOUNTAIN SLOPES. THE MOST LIKELY PLACES FOR ACCUMULATING RAINFALL
ARE IN THE SAN DIEGO COAST, VALLEYS, AND MOUNTAINS.
STRONGER, GUSTY SOUTHWEST TO WEST WINDS ARE EXPECTED FOR THE DESERT
SLOPES OF THE MOUNTAINS AND DESERTS FOR SATURDAY AFTERNOON INTO
SATURDAY NIGHT. STRONGER GUSTS OF 45 TO 55 MPH WITH ISOLATED GUSTS
TO 70 MPH IN THE NORTHERN COACHELLA VALLEY BELOW THE SAN GORGONIO
PASS ARE EXPECTED. GUSTY WEST WINDS WILL CONTINUE SUNDAY AFTERNOON
AND EVENING BUT NOT QUITE AS STRONG WITH GUSTS TO 40 TO 50 MPH AND
ISOLATED GUSTS TO 65 MPH THROUGH WIND PRONE PASSES.
HIGH PRESSURE WILL BRING DRY WEATHER WITH WARMING MONDAY THROUGH
THURSDAY. CONDITIONS WILL WARM QUITE RAPIDLY BETWEEN SUNDAY AND
MONDAY, ESPECIALLY IN THE VALLEYS AND MOUNTAIN FOOTHILLS DUE TO A
BRIEF PERIOD OF OFFSHORE WINDS. HIGHS IN THE VALLEYS AND FOOTHILLS
WILL BE UP TO 10 DEGREES WARMER ON MONDAY COMPARED TO SUNDAY. AS
EARLY AS TUESDAY, HIGHS ALONG THE COAST AND VALLEYS WILL BE 10 TO 15
DEGREES ABOVE AVERAGE. THE WARMING WILL SPREAD FURTHER INLAND FOR
WEDNESDAY AND THURSDAY. FOR WEDNESDAY AND THURSDAY, NBM CHANCES FOR
HIGH TEMPERATURES IN THE WARMER PORTIONS OF THE INLAND EMPIRE TO
EXCEED 100 ARE AROUND 45 TO 55 PERCENT WITH NBM CHANCES FOR THE
WARMER PORTIONS OF THE LOWER DESERTS TO EXCEED 110 ON THURSDAY AT 5
TO 10 PERCENT. THE MARINE LAYER WILL BECOME SHALLOWER WITH NIGHT AND
MORNING COASTAL LOW CLOUDS NOT EXTENDING INLAND PAST THE FAR WESTERN
VALLEYS FOR WEDNESDAY AND THURSDAY.
AVIATION
170330Z...COAST/VALLEYS...LOW CLOUDS BASED 1500-2100 FT MSL WITH
TOPS TO 2700 FT HAVE DEVELOPED ALONG THE COAST AND WILL MOVE TO FILL
THE ENTIRE COASTAL BASIN TO THE WESTERN FOOTHILLS BY 09-11Z. PATCHY
DRIZZLE IS POSSIBLE OVERNIGHT BETWEEN 08-18Z, WHICH COULD LOCALLY
LOWER VIS TO 4-6SM AND CIGS TO 1000-1500 FT MSL. PARTIAL CLEARING
WILL OCCUR FOR EASTERN VALLEYS AFTER 18Z, BUT MOST OTHER AREAS WILL
REMAIN BKN-OVC ALL DAY, THOUGH CIGS WILL RISE TO 2000-3000 FT MSL.
MORE SCATTERED LIGHT SHOWERS/DRIZZLE ARE EXPECTED AFTER 00Z SUN.
MOUNTAINS/DESERTS...SCT HIGH CLOUDS LATE TONIGHT. LOCAL WEST TO
SOUTH GUSTS 25-40 KTS OVER THE DESERT FOOTHILLS AND THROUGH PASSES
WILL BECOME MORE WIDESPREAD THROUGH THE DESERTS AND STRENGTHEN TO 35-
55 KT AFTER 17Z SAT, PRODUCING STRONG UP/DOWNDRAFTS IN THE LEE OF
MOUNTAINS SUCH AS VCNTY KPSP.
MARINE
ONSHORE WINDS GUSTING NEAR 20 KTS NEAR SAN CLEMENTE ISLAND LATE
SATURDAY INTO EARLY SUNDAY MAY LEAD TO SOME CHOPPY SEAS IN THE OUTER
WATERS FOR SATURDAY EVENING. OTHERWISE, NO HAZARDOUS MARINE
CONDITIONS EXPECTED THROUGH WEDNESDAY.
BEACHES
ELEVATED SURF WILL IMPACT BEACHES SUNDAY AND MONDAY. EXPECTED SURF
OF 4-6 FEET WOULD PRODUCE A HIGH RIP CURRENT RISK.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...WIND ADVISORY FROM NOON SATURDAY TO 2 AM PDT SUNDAY FOR APPLE
AND LUCERNE VALLEYS-RIVERSIDE COUNTY MOUNTAINS-SAN
BERNARDINO COUNTY MOUNTAINS-SAN DIEGO COUNTY DESERTS-SAN
DIEGO COUNTY MOUNTAINS-SAN GORGONIO PASS NEAR BANNING.
PZ...NONE.
UPDATE...STEWEY
PUBLIC...CO
AVIATION/MARINE...CSP
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