146
FXUS66 KSGX 200533 CCA
AFDSGX
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE SAN DIEGO CA
933 PM PST FRI DEC 19 2025
SYNOPSIS
HIGH PRESSURE WILL BEGIN TO WEAKEN OVER THE AREA INTO THE WEEKEND,
WHICH WILL CONTINUE TO PROVIDE WARM CONDITIONS. PATCHY FOG WILL
CONTINUE NEAR THE COAST AND WESTERN VALLEYS INTO EARLY NEXT WEEK.
AN AREA OF LOW PRESSURE WILL PUSH AN ATMOSPHERIC RIVER OVER THE
REGION AROUND THE CHRISTMAS HOLIDAY, WHERE THERE IS AN INCREASED
RISK OF HEAVY RAIN AND FLOODING. THE AREA OF LOW PRESSURE MAY
STICK AROUND INTO THE LATTER NEXT WEEK, LEADING TO MORE CHANCES
FOR RAIN AND HIGH ELEVATION SNOW.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
UPDATE: THE LOW CLOUDS AND FOG CURRENTLY STRETCHED ALONG THE COASTAL
AREAS OF SAN DIEGO COUNTY, AND WITHIN PORTIONS OF THE INLAND
VALLEYS, IS CONTINUING TO LIFT. THIS WILL ALLOW FOR VISIBILITIES TO
CONTINUE TO IMPROVE FOR THE COASTAL AREAS, AND CAUSE THESE CLOUDS TO
PENETRATE FURTHER EASTWARD THROUGHOUT THE NIGHT. THESE CLOUDS WILL
ALSO CONTINUE TO FILL INTO THE IE BY LATER TONIGHT AND INTO TOMORROW
MORNING AS WELL. THE MARINE LAYER WILL CONTINUE TO LIFT AND THICKEN
THROUGHOUT THE WEEKEND AS THE REGION BEGINS TO BECOME MORE
INFLUENCED BY THE BROAD AREA OF TROUGHING OVER THE E PACIFIC OCEAN,
WHICH IS SLOWLY ADVANCING TOWARDS THE REGION. IN GENERAL, THERE HAS
BEEN LITTLE CHANGE IN THE FORECAST, WHICH STILL SHOWS THE MAIN BRUNT
OF THE SHOWERS ASSOCIATED WITH THE FIRST INITIAL SHORTWAVE TO BEGIN
TO MOVE INTO THE COASTAL AREAS OF ORANGE COUNTY BY AS EARLY AS
TUESDAY MORNING, AND THEN THE HEAVIEST PRECIPITATION WILL LIKELY
OCCUR ON CHRISTMAS EVE (WEDNESDAY), AS THE MAIN FRONTAL BOUNDARY
WITH THIS SYSTEM MOVES OVERHEAD. THERE COULD ALSO BE SOME PATCHY
AREAS OF DRIZZLE AS THE MARINE LAYER CONTINUES TO THICKEN UP AHEAD
OF THIS TROUGH ON MONDAY. THERE WILL ALSO BE A BIT OF A STALLING OUT
OF THE PROGRESSION OF THIS TROUGH, AND THEN A SECONDARY LOW WILL
LIKELY CONTINUE IN CHRISTMAS ON THURSDAY, WITH A COLDER CORE
TRANSITIONING OVER SOCAL, WHICH WILL HELP TO ALSO LOWER SNOW LEVELS
(WITH POSSIBLY BIG BEAR GETTING IN ON SOME SNOW). AFTER CHRISTMAS,
THERE IS SOME DEVIATION WITH THE DETERMINISTIC MODELS ON HOW LONG
THE DURATION OF THIS TROUGH REMAINS IN PLACE OVER E PAC WATERS, WITH
A FEW OF THE MEMBERS KEEPING THE CHANCE OF PRECIPITATION GOING INTO
THE FOLLOWING WEEKEND, WHILE OTHERS HAVE MOSTLY EVERYTHING CLEARING
OUT BY FRIDAY. WE WILL CONTINUE TO EVALUATE THIS IN THE UPCOMING
DAYS.
..PREVIOUS DISCUSSION (1029 AM FRIDAY)
A 1023MB AREA OF HIGH PRESSURE TO THE SOUTHWEST WILL CONTINUE TO
DOMINATE OUR WEATHER PATTERN THROUGH THE WEEKEND. VISIBLE
SATELLITE SHOWS DENSE FOG PERSISTENT OVER THE WATERS AND PARTS OF
THE COASTLINE THIS MORNING. INTERMITTENT FOG WILL CONTINUE
THROUGHOUT THE DAY NEAR THE BEACHES BEFORE CLOUDS MOVE AROUND 5-10
MILES INLAND WHERE THE FOGGIEST CONDITIONS WILL OCCUR ON ELEVATED
COASTAL TERRAIN. AS THE RIDGE OF HIGH PRESSURE SLOWLY BREAKS
DOWN, A SLIGHT INCREASE IN ONSHORE FLOW WILL OCCUR, COOLING THE
COAST AND VALLEYS A FEW DEGREES FROM YESTERDAY. THE MOUNTAINS AND
DESERTS WILL SEE SIMILAR TEMPERATURES WITH HIGHS IN THE 70S/80S
ACROSS THE DESERTS. THE COOLING WILL SLOWLY CONTINUE INTO THE
WEEKEND AND MONDAY AS THE MARINE LAYER DEEPENS, THOUGH HIGHS WILL
REMAIN ABOVE AVERAGE. HIGHS WILL BE 5-10 DEGREES ABOVE NORMAL WEST
OF THE MOUNTAINS AND 10-15 DEGREES ABOVE NORMAL IN THE MOUNTAINS
AND DESERTS.
TWO FEATURES TO THE NORTH WILL LEAD TO A BIG CHANGE IN THE WEATHER
AS WE HEAD INTO THE CHRISTMAS HOLIDAY. AN ATMOSPHERIC RIVER SEEN
FROM THE HAWAIIAN ISLANDS INTO NORTHERN CALIFORNIA AND AN AREA OF
LOW PRESSURE OVER THE EASTERN GULF OF ALASKA WILL BEGIN TO PUSH
SOUTHWARD BY MONDAY AND TUESDAY OF NEXT WEEK. THE TROUGH OF LOW
PRESSURE WILL AID TO PUSH THE ATMOSPHERIC RIVER SOUTHWARD,
ORIENTING THE SYSTEM IN A MORE NORTH/SOUTH DIRECTION. THIS WILL
FIRST PROVIDE HEAVY RAIN TO PARTS OF THE CENTRAL COAST LATE MONDAY
NIGHT INTO TUESDAY AND PUSH SOUTHWARD INTO OUR REGION LATE TUESDAY
INTO WEDNESDAY. AS A SERIES OF SHORTWAVES PASS THE TROUGH'S AXIS,
RAPID DEEPENING OF THE LOW WILL OCCUR. CONFIDENCE ON TIMING
CONTINUES TO INCREASE WITH THE HEAVIEST RAIN FALLING FROM THE
ATMOSPHERIC RIVER ON WEDNESDAY (CHRISTMAS EVE DAY). THE WIND
FORECAST HAS INCREASED AS MODELS SHOW HIGHER CHANCES FOR WIND
GUSTS MAINLY ACROSS THE IMMEDIATE COAST AND MOUNTAIN AREAS TO GUST
OVER 30 MPH AT TIMES AS THE AR PASSES BY ON WEDNESDAY.
A SECONDARY SHORTWAVE IN THE TROUGH MAY PROVIDE ANOTHER MODERATE
TO HEAVIER ROUND OF PRECIPITATION ON CHRISTMAS DAY. THE TRACK
OF THE LARGE LOW PRESSURE SYSTEM STILL REMAINS UNCERTAIN. SOME
MODELS SHOW A SLOWER MOVING SYSTEM, WHICH WOULD GIVE US MORE
CHANCES OF RAIN INTO NEXT WEEKEND, WHILE OTHERS SHOW A FASTER AND
NOT AS WET SOLUTION. MODEL ENSEMBLE TRENDS SHOW A SLIGHT INCREASE
OVER THE PAST FEW DAYS, SO RAIN CHANCES CONTINUE INTO THE FORECAST
FOR LATER NEXT WEEK.
AVIATION
200530Z...COAST/WESTERN VALLEYS...LOW CLOUDS AND FOG SPREADING
INLAND AT THIS HOUR IMPACTING COASTAL TAF SITES WITH CIG AND VIS
RESTRICTIONS. LOW CLOUDS LIKELY TO REACH 15-20 MILES INLAND BY
SUNRISE AND COULD APPROACH KONT AROUND 12Z BUT CONFIDENCE IS NOT
HIGH. CLOUD BASES WILL BE AROUND 300 FT MSL VCNTY KSNA AND ABOUT
1000 FT MSL VCNTY KSAN, RISING AFTER SUNRISE. LOCAL VIS RESTRICTIONS
BLO 1SM VCNTY KSNA...IMPROVING AFTER 15Z. EXPECT PARTIAL CLEARING TO
THE COAST 17Z-19Z.
OTHERWISE...FEW-SCT HIGH CLOUDS WITH UNRESTRICTED VIS THROUGH
SATURDAY MORNING.
MARINE
AREAS OF FOG WITH REDUCED VISIBILITY BELOW 1 NAUTICAL MILE THROUGH
SATURDAY MORNING. FOLLOWING THAT, NO HAZARDOUS MARINE CONDITIONS ARE
EXPECTED THROUGH TUESDAY MORNING. INCREASING SOUTH WINDS DEVELOP
LATE TUESDAY IN ADVANCE OF A PACIFIC STORM. CONDITIONS COULD BECOME
HAZARDOUS TO SMALL CRAFT TUESDAY NIGHT THROUGH WEDNESDAY.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...NONE.
UPDATE...STEWEY
PUBLIC...APR
AVIATION/MARINE...PG
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