683
FXUS66 KSGX 211445
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
645 AM PST SAT DEC 21 2024
SYNOPSIS
PATCHY CLOUDS AND FOG LINGER NEAR THE COAST WITH SOME HIGHER LEVEL
CLOUDS FOR INLAND AREAS TODAY. WARM WEATHER WILL CONTINUE INLAND
WHILE TEMPERATURES STAY NEAR AVERAGE AT THE COAST THIS WEEKEND. A
TROUGH OFF THE PACIFIC WILL BRING COOLER AND BREEZIER WEATHER BY
THE MIDDLE OF THE WEEK WITH A CHANCE OF LIGHT SHOWERS. HIGHS WILL
GENERALLY STAY NEAR TO SLIGHTLY ABOVE AVERAGE WITH DRY WEATHER BY
THE END OF THE WEEK AS HIGH PRESSURE BUILDS IN FROM THE SOUTHWEST.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
A TROUGH OFF THE CALIFORNIA COAST WILL MOVE ASHORE TODAY. THIS HAS
BEGUN TO STREAM IN MID-LEVEL CLOUDS ACROSS SOCAL, WHILE THE MARINE
LAYER STAYS THIN WITH FOGGY CONDITIONS NEAR THE SAN DIEGO COUNTY
COASTLINE. ANOTHER DAY, ANOTHER 1/16TH OF A MILE VISIBILITY AT
SAN DIEGO INT'L. LOW CLOUDS MAY LOCALLY STICK NEAR THE COAST
THROUGH THE DAY, WHILE HIGHER CLOUDS STAY WITH US THIS MORNING
AND SCATTER A BIT MORE THIS AFTERNOON. PRESSURE HEIGHTS WILL LOWER
A BIT OVER THE WEEKEND, SO SOME IMPROVEMENTS IN VISIBILITY WILL
OCCUR ALONG THE COAST, WITH FOGGIEST CONDITIONS BECOMING MORE
CONFINED TO THE ADJACENT COASTAL VALLEYS. OTHERWISE, DRY WEATHER
WILL CONTINUE WITH HIGHS REMAINING 5-15 DEGREES ABOVE NORMAL FOR
INLAND AREAS; TEMPERATURES WILL BE IN THE 60S AND 70S FOR AREAS
BELOW 5,000 FEET AND NEAR 80 ACROSS THE COACHELLA VALLEY AND ANZA-
BORREGO DESERT.
THE ACTIVE PATTERN OVER THE PACIFIC WILL GENERATE ANOTHER TROUGH
OF LOW PRESSURE MOVING INTO OUR AREA BY TUESDAY. CONFIDENCE IS
INCREASING ON SEEING CLOUDS AND A 30-50% CHANCE OF SHOWERS BY
TUESDAY AFTERNOON THROUGH NIGHT ACROSS OUR REGION. MOST OF THE
SHOWER ACTIVITY WILL OCCUR ALONG AND WEST OF THE MOUNTAINS, WITH
MINOR CHANCES FOR THE DESERTS. WHATEVER DOES FALL WILL BE LIGHT.
MOST AREAS WILL SEE A FEW HUNDREDTHS WHILE COASTAL SLOPE REGIONS
WILL SEE NEAR ONE TENTH OF AN INCH. AS THE TROUGH MOVES THROUGH,
EXPECT WINDS TO PICK UP IN OUR GENERALLY WINDIER AREAS OF THE
MOUNTAINS AND DESERTS BY LATER IN THE AFTERNOON ON TUESDAY INTO
THE OVERNIGHT HOURS. NOTICEABLY COOLER CONDITIONS WILL OCCUR BY
WEDNESDAY FOR THE MOUNTAINS AND DESERTS AS WELL WHERE TEMPERATURES
WILL LOWER INTO THE 70S FOR THE LOWER DESERTS AND 50S FOR THE HIGH
DESERT. OTHER THAN THIS, CHRISTMAS DAY WILL BE DRY AND SEASONAL.
HIGH PRESSURE TO THE SOUTHWEST WILL SLOWLY REGAIN MOMENTUM BY
LATER IN THE WEEK PER LATEST CLUSTER ENSEMBLE GUIDANCE. THIS WILL
DIMINISH CHANCES FOR PRECIPITATION AS WELL AS RETURN TEMPERATURES
TO ABOVE AVERAGE ACROSS THE INLAND VALLEYS.
AVIATION
211100Z....COASTS...A PATCH OF LOW CLOUDS BASED AT 200-300 FEET MSL
HAS FILLED IN ACROSS COASTAL SAN DIEGO COUNTY, WITH VIS AT OR BELOW
1/2 SM. LIGHT OFFSHORE FLOW IS LIMITING INLAND EXTENT AND HAS HELPED
NUDGE THE CLOUDS WESTWARD AND EVEN OFFSHORE IN SPOTS. KCRQ HAS SINCE
CLEARED WHILE KSAN REMAINS SOLIDLY WITHIN THE FOG DECK. ORANGE
COUNTY REMAINS FREE OF LOW CLOUDS FOR NOW WITH AREAS OF VIS 3-6SM IN
BR BUT A DECK OF LOW CLOUDS BASED AT 200FT MSL WITH DENSE FOG (VIS
<1/2 SM) IS APPROACHING FROM THE WEST AND SHOULD ARRIVE BY 12Z. ONCE
THIS ARRIVES, KSAN AND KSNA COULD CONTINUE TO SEE VIS <1/2 SM
THROUGH AT LEAST 15Z WHILE KCRQ LOOKS TO STAY JUST TO THE EAST OF
THE FOG, BUT WILL BE UNCOMFORTABLY CLOSE.
SOME VIS IMPROVEMENTS AND CLEARING MAY BEGIN TO OCCUR AROUND 15-16Z
BUT COULD STICK AROUND AT KSAN/KSNA THROUGH 18Z. MOSTLY CLEAR
CONDITIONS EXPECTED THEREAFTER THOUGH SOME PATCHES OF LOW CLOUDS/FOG
COULD LINGER INTO THE AFTERNOON ALONG THE BEACHES. LOW CLOUDS AND
FOG LOOK TO MAKE A RESURGENCE IN THE EVENING, POSSIBLY AS EARLY AS
00-01Z, WITH MUCH HIGHER CONFIDENCE IN CIGS AFTER 05-06Z SUNDAY.
BASES AND VIS RESTRICTIONS WILL LIKELY BE SIMILAR TO THIS MORNING'S
BUT BASES MAY BE ~100FT OR SO HIGHER.
VALLEYS/MOUNTAINS/DESERTS
VFR CONDITIONS WILL PREVAIL THROUGH
EARLY SUNDAY MORNING, BUT WITH AN INCREASE IN HIGH CLOUDS ABOVE
20000 FEET MSL FOR SATURDAY MORNING/AFTERNOON.
MARINE
PATCHY DENSE FOG WITH VISIBILITY BELOW 1 NM AT TIMES WILL CONTINUE
THROUGH SATURDAY MORNING, ESPECIALLY FOR THE NEARSHORE WATERS.
ROUNDS OF OVERNIGHT/MORNING FOG REMAINS POSSIBLE THROUGH AT LEAST
TUESDAY.
LONG PERIOD WEST SWELLS OF 8-11 FEET ARE EXPECTED SUNDAY THROUGH
TUESDAY NIGHT, HIGHEST IN THE OUTER COASTAL WATERS WHERE A SMALL
CRAFT ADVISORY HAS BEEN ISSUED. 8-9 FEET WAVES POSSIBLE WITHIN 10-30
NM OF THE COAST BUT SHOULD STILL BE ENOUGH OFFSHORE TO LIMIT ANY
NEARSHORE IMPACTS. WIND GUSTS OF 20-25 KTS ARE EXPECTED TUESDAY
NIGHT IN THE OUTER COASTAL WATERS.
BEACHES
LONG PERIOD (16-19 SECOND) WEST TO NORTHWEST SWELLS (280-290
DEGREES) ARRIVE EARLY SUNDAY AND INTO NEXT WEEK, RESULTING IN HIGH
SURF OF 6-12 FEET WITH LOCALLY HIGHER SETS CONTINUING THROUGH
WEDNESDAY. THIS WILL MAKE SWIMMING HAZARDOUS AND POSE A COASTAL
FLOODING THREAT. SEE THE HIGH SURF ADVISORY FOR MORE DETAILS.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...DENSE FOG ADVISORY UNTIL 9 AM PST THIS MORNING FOR SAN DIEGO
COUNTY COASTAL AREAS-SAN DIEGO COUNTY VALLEYS.
HIGH SURF ADVISORY FROM 10 PM THIS EVENING TO 4 AM PST WEDNESDAY
FOR ORANGE COUNTY COASTAL AREAS-SAN DIEGO COUNTY COASTAL
AREAS.
DENSE FOG ADVISORY UNTIL 9 AM PST THIS MORNING FOR ORANGE COUNTY
COASTAL AREAS-ORANGE COUNTY INLAND AREAS.
PZ...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 4 AM PST
WEDNESDAY FOR WATERS FROM SAN MATEO POINT TO THE MEXICAN
BORDER EXTENDING 30 TO 60 NM OUT INCLUDING SAN CLEMENTE
ISLAND.
PUBLIC...APR
AVIATION/MARINE/BEACHES...MUNYAN
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