922
FXUS66 KSGX 200545
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
930 PM PST THU DEC 19 2024
SYNOPSIS
AREAS OF LOW CLOUDS AND DENSE FOG WILL CONTINUE NEAR THE COAST
THROUGH MID-MORNING FRIDAY. CONDITIONS WILL GRADUALLY COOL A FEW
DEGREES EACH DAY FRIDAY THROUGH THE WEEKEND. NIGHT AND MORNING LOW
CLOUDS AND FOG ARE EXPECTED OVER THE WEEKEND, GRADUALLY SPREADING
FURTHER INLAND EACH DAY. A TROUGH OF LOW PRESSURE WILL BRING GUSTY
WESTERLY WINDS OVER THE MOUNTAINS AND DESERTS AND A CHANCE OF
SHOWERS TUESDAY. DRY CONDITIONS SHOULD RETURN WEDNESDAY.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
UPDATE...
DENSE FOG WAS IMPACTING COASTAL AREAS AT MID-EVENING, INCLUDING
VISIBILITY OF 1/8 TO 1/4 MILE AT SAN, AND DENSE FOG WAS MOVING INTO
SNA AS WELL. WITH LIGHT WINDS OVERNIGHT, THIS FOG WILL CONTINUE,
THOUGH LIGHT DRAINAGE FLOW FROM THE EAST WILL PREVENT THIS FOG FROM
GOING TOO FAR INLAND, ESPECIALLY IN SAN DIEGO COUNTY WHERE IT WILL
REMAIN MOSTLY ALONG AND WEST OF INTERSTATE 805. CLEARING TIME WILL
MOSTLY BE IN THE MID-LATE MORNING FRIDAY, EXCEPT ALONG THE IMMEDIATE
COAST. CURRENT PROJECTIONS ARE FOR SLIGHT DEEPENING OF THE MARINE
LAYER FRIDAY NIGHT, THOUGH AREAS OF DENSE FOG COULD STILL OCCUR,
MOSTLY SEVERAL HUNDRED FEET ABOVE SEA LEVEL VERSUS AT SEA LEVEL
TONIGHT.
PREVIOUS DISCUSSION...
AT 1 PM, THERE WAS LOCALLY DENSE FOG ALONG THE SOUTHERN SAN DIEGO
COAST WITH AREAS OF HIGH CLOUDS MOVING NORTHWEST TO SOUTHEAST ACROSS
THE AREA. THE HREF IS SHOWING 30 TO 40 PERCENT CHANCE OF DENSE FOG
MAINLY ALONG THE INTERSTATE 5 CORRIDOR TONIGHT INTO EARLY FRIDAY
MORNING. HIGHEST CHANCES ARE NEAR THE ORANGE/LA COUNTY LINE AND
SOUTHERN SAN DIEGO COUNTY. LOW CLOUDS AND FOG ARE EXPECTED TO BE
PRESENT EACH NIGHT AND MORNING THROUGH THE WEEKEND. OVER THE NEXT
FEW DAYS, HIGH PRESSURE ALOFT WEAKENS WHICH WILL HELP THE MARINE
LAYER DEEPEN ALLOWING COASTAL LOW CLOUDS AND FOG TO EXTEND A LITTLE
FARTHER INLAND EACH NIGHT AND MORNING. WITH THE DEEPENING OF THE
MARINE LAYER, FOG AND VISIBILITY ISSUES WILL BECOME LESS OF A
PROBLEM ALONG THE COAST OVER THE WEEKEND.
A GRADUAL COOLING TREND IS EXPECTED FOR FRIDAY THROUGH THE WEEKEND
AS AN UPPER LEVEL TROUGH APPROACHES THE PACIFIC NORTHWEST. THE
TROUGH IS NOT EXPECTED TO DIG FAR ENOUGH SOUTH TO BRING
PRECIPITATION TO SOUTHERN CALIFORNIA, BUT PERIODS OF HIGH CLOUDS CAN
BE EXPECTED IN ADDITION TO THE GRADUAL COOLING. WEAK RIDGING ALOFT
WILL MOVE OVER SOUTHERN CALIFORNIA FOR MONDAY, BRINGING A FEW
DEGREES OF WARMING.
FOR TUESDAY A QUICK MOVING TROUGH OF LOW PRESSURE WILL MOVE ACROSS
THE WEST COAST. LATEST GUIDANCE IS INDICATING LIGHT RAIN IS POSSIBLE
FROM THE COAST TO THE MOUNTAINS. ONSHORE WESTERLY WINDS WILL
INCREASE TUESDAY AND PEAK TUESDAY NIGHT, STRONGEST IN THE MOUNTAINS
AND DESERTS. GUIDANCE IS FAIRLY CONSISTENT ON THE TIMING BEING
TUESDAY AFTERNOON AND EVENING FOR BOTH THE WIND AND PRECIPITATION.
SNOW LEVELS ARE EXPECTED TO STAY ABOVE 7000 FT. GUIDANCE FROM THE
NBM HAS A 40 PERCENT CHANCE OF AT LEAST 0.25" OF RAIN IN THE SAN
BERNARDINO COUNTY MOUNTAINS, WITH ONLY 25 PERCENT CHANCE OF AT LEAST
0.25" IN THE RIVERSIDE AND SAN DIEGO COUNTY MOUNTAINS OVER A 24 HOUR
PERIOD ENDING WEDNESDAY MORNING. FOR THE COAST AND VALLEYS, THERE IS
A 25 TO 35 PERCENT CHANCE OF AT LEAST 0.10" OF RAIN ACCUMULATING
OVER A 24 HOUR PERIOD ENDING WEDNESDAY MORNING. THE TROUGH IS
EXPECTED TO QUICKLY EXIT TO THE EAST, LEAVING DRY CONDITIONS IN IT'S
WAKE FOR MUCH OF WEDNESDAY.
AVIATION
200530Z....COASTS/VALLEYS...AREAS OF DENSE FOG AND VERY LOW CIGS
WILL CONTINUE THROUGH 16Z-18Z FRI WITHIN 6-12 MILES OF THE OCAST.
VIS WILL BE ONE MILE OR LESS AT TIMES, WITH CIGS OF 200 FEET OR LESS
MSL, IMPACTING SAN, CRQ AND SNA MOST OF THE TIME. AFTER THE 16Z-19Z
FRI CLEARING, ISOLATED BKN CIGS/FOG WILL CONTINUE NEAR THE BEACHES
FRI AFTERNOON, BUT AWAY FROM THE BEACHES, MOST VIS WILL BE ABOVE 5
MILES, WITH MOSTLY CLEAR SKIES. MORE LOW STRATUS/FOG WILL DEVELOP
FRI EVENING, WITH SLIGHTLY HIGHER BASES/VIS NEAR THE COAST BUT
LIKELY A MORE INLAND EXTENT FRI NIGHT.
MOUNTAINS/DESERTS
MOSTLY CLEAR SKIES AND UNRESTRICTED VIS WILL
PREVAIL THROUGH FRI EVENING.
MARINE
DENSE FOG WITH VISIBILITY BELOW 1 NM AT TIMES WILL CONTINUE THROUGH
FRIDAY MORNING, LIFTING GRADUALLY LATE IN THE MORNING. LONG PERIOD
WEST SWELL WILL GENERATE SEAS OF 8-11 FEET SUNDAY THROUGH WEDNESDAY,
HIGHEST IN THE OUTER COASTAL WATERS AND NEAR SAN CLEMENTE ISLAND.
BEACHES
A SERIES OF 16-18 SECOND PERIOD WEST SWELLS (280-290 DEGREES)
BEGINNING SUNDAY WILL BRING HIGH SURF OF 7 TO 12 FEET WITH LOCALLY
HIGHER SETS PRIMARILY AT SAN DIEGO COUNTY BEACHES WHILE ORANGE
COUNTY BEACHES WILL HAVE SURF 5 TO 10 FEET BUT ALSO WITH LOCALLY
HIGHER SETS. REINFORCING LONG PERIOD SWELLS MAY MAINTAIN
ELEVATED/HIGH SURF THE SECOND HALF OF NEXT WEEK, THOUGH WITH SURF
HEIGHTS SLIGHTLY LOWER THAN EARLY IN THE WEEK. THERE WILL BE A HIGH
RISK OF STRONG RIP CURRENTS AND DANGEROUS SWIMMING CONDITIONS, WITH
ADDITIONAL COASTAL IMPACTS POSSIBLE, SUCH AS COASTAL FLOODING NEXT
WEEK.
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 10 AM PST FRIDAY FOR ORANGE COUNTY
COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS.
PZ...NONE.
PUBLIC...MAXWELL (UPDATE)/CO (PREVIOUS DISCUSSION)
AVIATION/MARINE/BEACHES...MAXWELL
CLICK HERE TO GO TO PREVIOUS BULLETINS.
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