179
FXUS66 KSGX 290446
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
946 PM PDT FRI MAR 28 2025
SYNOPSIS
A DEEP MARINE LAYER WILL CONTINUE THROUGH THE WEEKEND WITH COOLER
WEATHER AND PATCHY DRIZZLE WEST OF THE MOUNTAINS EACH MORNING.
QUITE THE CONSISTENT TROUGHING PATTERN WILL HANG ON THROUGH THE
NEXT WEEK, LEADING TO WINDY CONDITIONS ACROSS THE MOUNTAINS AND
DESERTS WITH HIGHS UP TO 10 DEGREES BELOW AVERAGE EACH DAY.
CHANCES FOR MORE SUBSTANTIAL PRECIPITATION OCCUR LATER IN THE WEEK
WITH LOWER CONFIDENCE.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
MANY AREAS ALONG AND WEST OF THE MOUNTAINS REMAINED AT LEAST
PARTLY CLOUDY THROUGH THE DAY TODAY, AND NUMEROUS MID AND HIGH
LEVEL CLOUDS ARE CURRENTLY MOVING OVER THE AREA AHEAD OF AN UPPER
LEVEL TROUGH OFF THE WEST COAST. A SHORT-WAVE TROUGH MOVING INTO
THE BAY AREA IS EVIDENT IN WATER VAPOR IMAGERY. THIS TROUGH WILL
PROGRSS EASTWARD OVERNIGHT, WITH THE TAIL END BRUSHING OUR REGION.
THIS, COMBINED WITH THE DEVELOPMENT OF A COASTAL EDDY, WILL HELP
DEEPEN THE MARINE LAYER AGAIN TONIGHT AND PRODUCE AREAS OF DRIZZLE
OR SPOTTY LIGHT SHOWERS. HREF PROBABILITIES OF 0.10" OF
PRECIPITATION OR MORE TONIGHT ARE GENERALLY LESS THAN 10% ACROSS
THE COASTS AND VALLEYS, LOCALLY AROUND 20-40% ALONG THE COASTAL
SLOPES OF THE MOUNTAINS. MORE LIKELY IT WILL BE A FEW HUNDREDTHS
HERE OR THERE. OTHERWISE GUSTY WEST WINDS WILL CONTINUE ALONG THE
DESERT MOUNTAIN SLOPES AND DESERTS OVERNIGHT, STRONGEST THROUGH
THE PASSES WHERE GUSTS OF 45-55 MPH ARE EXPECTED. A MUCH WEAKER
SHORT WAVE MOVES THROUGH THE ZONAL FLOW ON SUNDAY. WITH A DEEP
MARINE LAYER STILL IN PLACE CAN'T RULE OUT ANOTHER MORNING OF
DRIZZLE WITH THIS WAVE, THOUGH THE POTENTIAL FOR MEASURABLE
PRECIPITATION IS LOWER. THIS PATTERN WILL ALSO MAINTAIN GUSTY
WESTERLY WINDS IN THE MOUNTAINS AND DESERTS, STRONGEST IN THE
DESERTS.
PRECIPITABLE WATER INCREASES LATE SUNDAY INTO MONDAY AS A WEAK
ATMOSPHERIC RIVER MOVES INTO SO CAL. WHILE THERE ARE SOME TIMING
DIFFERENCES, BOTH THE EPS AND GEFS ENSEMBLES HAVE PROBABILITIES OF
IVT IN EXCESS OF 250 KG/M/S OF 80% OR HIGHER. DESPITE THIS INFLUX
OF MOISTURE, WE REMAIN UNDER MOSTLY ZONAL FLOW WITH LIMITED
FORCING, SO IT MAY BE YET ANOTHER CASE WHERE THE LOWER ELEVATIONS
DON'T SEE MUCH PRECIPITATION (0.10" OR LESS), WHILE THE COASTAL
SLOPES GET MANY TIMES AS MUCH ACCUMULATION DUE TO THE STRONGER
ONSHORE FLOW/OROGRAPHIC LIFT. FOR LOCATIONS SUCH AS LYTLE CREEK,
THE CW3E WRF ENSEMBLE HAS AROUND A 25% CHANCE OF A STORM TOTAL OF 0.25"
OR MORE AND A 15% CHANCE OF 0.50" OR MORE, MEANWHILE FOR THE
COASTAL AREAS AND VALLEYS THE PROBABILITIES OF THOSE RAIN AMOUNTS
ARE LESS THAN 10%. THE NBM IS LESS ENTHUSIASTIC WITH CHANCES OF
0.10" OR MORE ESSENTIALLY 0% ACROSS THE REGION.
ONCE THAT MOVES THROUGH WE WILL HAVE A COUPLE DAYS OF DRYING, THEN
THE POTENTIAL FOR A LONG-WAVE TROUGH TO MOVE ACROSS THE AREA LATE
IN THE WEEK FOR A 35-45% OF PRECIPITATION WITH THE POTENTIAL FOR
HIGHER RAINFALL AMOUNTS. OTHERWISE COOL WITH TEMPERATURES
REMAINING BELOW NORMAL FOR THE NEXT WEEK.
AVIATION
290330Z...COAST/VALLEYS/FOOTHILLS...LOW CLOUDS BASED AT 1500-4000
FEET MSL AND TOPS TO 5500 FEET WILL LOWER TO MOSTLY AROUND 1500 FEET
OVERNIGHT, EXCEPT IN VCNTY KSNA WHERE CIGS WILL BE INTERMITTENT
OVERNIGHT. PATCHY -DZ AND VIS 4-6SM AND AREAS OF VIS 0-2SM ON
FOOTHILLS. AFTER 15Z SATURDAY, CLOUDS WILL SLOWLY LIFT AND THEN
PARTIALLY CLEAR BY 18-19Z. PATCHY BKN CLOUDS AOA 3000 FEET SATURDAY
AFTERNOON. LOW CLOUDS TO GATHER AGAIN AFTER 00Z SATURDAY EVENING,
MOSTLY BETWEEN 2000-3000 FEET MSL. ABOVE THE DEEP MARINE LAYER, SCT-
BKN HIGH CLOUDS AOA 20000 FEET MSL THROUGH SATURDAY.
HIGHER MOUNTAINS/DESERTS...BKN-SCT HIGH CLOUDS AOA 20000 FEET MSL
THROUGH SATURDAY. STRONG WESTERLY WINDS WITH GUSTS 30-50 KTS OVER
THE RIDGES AND DESERT SLOPES THROUGH SATURDAY. AREAS OF MODERATE
UP/DOWNDRAFTS, INCLUDING LOCALIZED LLWS AND ROTORS, IN LEE OF
MOUNTAINS.
MARINE
STRONG NORTHWEST WINDS AND STEEP WAVES WILL CONTINUE THROUGH EARLY
SATURDAY, DIMINISHING DURING THE DAY. A SMALL CRAFT ADVISORY
CONTAINS THE DETAILS. WINDS AND WAVES WILL REMAIN SOMEWHAT ELEVATED
THROUGH TUESDAY, BUT AT THIS TIME THEY ARE NOT EXPECTED TO BE
HAZARDOUS.
BEACHES
ELEVATED SURF OF 4-8 FEET, WITH LOCAL SETS TO 10 FEET IS EXPECTED
THROUGH SATURDAY AFTERNOON. THIS WILL CREATE A HIGH RIP CURRENT RISK
AND ASSOCIATED DANGEROUS SWIMMING CONDITIONS, AS WELL AS POSSIBLE
COASTAL EROSION. A HIGH SURF ADVISORY AND A BEACH HAZARDS STATEMENT
REMAINS IN EFFECT AND CONTAINS MORE DETAILS.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...HIGH SURF ADVISORY UNTIL 4 PM PDT SATURDAY FOR SAN DIEGO COUNTY
COASTAL AREAS.
WIND ADVISORY UNTIL 11 AM PDT SATURDAY FOR SAN DIEGO COUNTY
DESERTS.
BEACH HAZARDS STATEMENT THROUGH SATURDAY AFTERNOON FOR ORANGE
COUNTY COASTAL AREAS.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT SATURDAY FOR WATERS FROM SAN
MATEO POINT TO THE MEXICAN BORDER EXTENDING 10 TO 60 NM OUT
INCLUDING SAN CLEMENTE ISLAND.
PUBLIC...SS
AVIATION/MARINE/BEACHES...MM
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