234
FXUS66 KSGX 180503
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
903 PM PST MON FEB 17 2025
SYNOPSIS
THE MARINE LAYER WILL DEEPEN TONIGHT WITH LOW CLOUDS EXTENDING
INTO THE INLAND VALLEYS. MINOR DAILY TEMPERATURE FLUCTUATIONS
THROUGH THURSDAY WITH AREAS OF NIGHT AND MORNING LOW CLOUDS AND
FOG FOR THE COASTAL AREAS AND FAR WESTERN VALLEYS. A MORE
SIGNIFICANT WARMING TREND FOLLOWS FOR FRIDAY THROUGH EARLY NEXT
WEEK WITH SUNDAY AND MONDAY HIGH TEMPERATURES AS MUCH AS 10 TO 15
DEGREES ABOVE AVERAGE FOR THE MOUNTAINS AND INLAND VALLEYS.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
MARINE LAYER LOW CLOUDS HAVE RETURNED TO THE COASTAL AREAS AND
WESTERN VALLEYS IN SAN DIEGO COUNTY. SURFACE OBS SHOW THAT THE
COASTAL EDDY HAS BEGUN TO DEVELOP AND SHOULD STRENGTHEN OVERNIGHT,
HELPING SPREAD LOW CLOUDS INTO ORANGE COUNTY AND THE INLAND EMPIRE
OVERNIGHT. THE 00Z KNKX SOUNDING SHOWS TWO INVERSIONS, ONE BASED
NEAR 1400 FT MSL AND ANOTHER AROUND 4700 FT MSL WITH A VERY DRY
LAYER IN BETWEEN THE TWO. GIVEN THE LACK OF A THICK STATUS DECK,
ANY MARINE LAYER DRIZZLE LOOKS UNLIKELY TONIGHT. WEAK OFFSHORE
FLOW DEVELOPING BY TUESDAY MORNING SHOULD HELP CLEAR OUT MARINE
LAYER CLOUDS FOR THE INLAND AREAS. OTHERWISE MINOR COOLING
TOMORROW AS A TROUGH DIGS SOUTHEAST THROUGH THE GREAT BASIN.
ANOTHER COASTAL EDDY IS FORECAST TO DEVELOP TUESDAY NIGHT INTO
WEDNESDAY MORNING, BUT WILL BE WORKING AGAINST RISING HEIGHTS AS A
FLATTENING RIDGE MOVES OVERHEAD, SO CLOUDS WILL NOT EXTEND AS FAR
INLAND. ALL AREAS SHOULD SEE A FEW DEGREES OF WARMING ON
WEDNESDAY.
ANOTHER WAVE PASSES BY TO OUR NORTH BEFORE DIGGING THROUGH THE
GREAT BASIN AND INTO THE DESERT SOUTHWEST THURSDAY INTO FRIDAY.
ENSEMBLES ARE IN GENERALLY GOOD AGREEMENT WITH THE TRACK OF THIS
WAVE, THOUGH ABOUT 41% OF THE SOLUTIONS SHOW A DEEPER TROUGH
CLOSER TO US ON FRIDAY, WHICH WOULD LEAD TO LESS WARMING AND
STRONGER OFFSHORE FLOW. WEAK OFFSHORE FLOW WILL DEVELOP ON
THURSDAY, PEAKING AT WEAK TO MODERATE ON FRIDAY AS SURFACE
PRESSURE GRADIENTS INCREASE. THE LOW MOVES OFF TO THE EAST ON
SATURDAY WITH ONLY WEAK OFFSHORE PRESSURE GRADIENTS REMAINING,
TURNING BACK ONSHORE BY SUNDAY AFTERNOON. OTHERWISE UPPER LEVEL
RIDGING WILL DOMINATE OVER THE WEEKEND INTO EARLY NEXT WEEK FOR
MORE SIGNIFICANT WARMING AND DRYING. BY SUNDAY HIGHS WILL BE
AROUND 8-11 DEGREES ABOVE NORMAL, INCREASING TO 10-15 DEGREES
ABOVE NORMAL AWAY FROM THE COAST ON MONDAY.
AVIATION
180430Z...COAST/VALLEYS...AIDED BY A BUILDING COASTAL EDDY, LOW
STRATUS BASED NEAR 1400-1600FT MSL HAVE BEEN BUILDING INTO COASTAL
SAN DIEGO COUNTY. THESE CLOUDS WILL CONTINUE TO FILL IN NORTHWARD
AND INTO THE SAN DIEGO COUNTY VALLEYS AND PORTIONS OF THE INLAND
EMPIRE. VIS RESTRICTIONS FROM THESE CLOUDS WILL GENERALLY BE LIMITED
TO WHERE THE CLOUDS INTERSECT INLAND HIGHER TERRAIN. CLOUDS BEGIN TO
SCATTER OUT AROUND 15-16Z IN THE INLAND AREAS FIRST, WITH FULL
CLEARING TO THE COASTS AROUND 17-18Z. OTHERWISE, SCT-BKN HIGH CLOUDS
CONTINUE INTO TUESDAY. LOW CLOUDS MAY RETURN AGAIN LATE TUESDAY
EVENING AROUND 09-12Z, CLOSER TO 1000FT MSL.
MOUNTAINS/DESERTS...WIND GUSTS CONTINUE TO GRADUALLY DECREASE THIS
EVENING, WITH VFR CONDITIONS PREVAILING. SCT-BKN HIGH CLOUDS
CONTINUE INTO TUESDAY.
MARINE
NO HAZARDOUS MARINE CONDITIONS ARE ANTICIPATED THROUGH SATURDAY.
BEACHES
A LONG-PERIOD SWELL WILL ARRIVE TUESDAY, GENERATING LARGE SURF -
ESPECIALLY FOR WEST FACING BEACHES - UP TO 6-7 FEET, A HIGH RIP
CURRENT RISK, AND SOME DANGEROUS SWIMMING CONDITIONS. SWELL AND SURF
WILL EASE SOMEWHAT 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.
PUBLIC...SS
AVIATION/MARINE/BEACHES...MUNYAN
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