613
FXUS66 KSGX 011701
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
1001 AM PDT TUE APR 1 2025
SYNOPSIS
AN EXTENSIVE LOW PRESSURE SYSTEM OVER THE WESTERN STATES WILL
MAINTAIN COOLER CONDITIONS INTO THURSDAY ALONG WITH OCCASIONAL
SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS THURSDAY AFTERNOON.
THERE WILL ALSO BE PERIODS OF STRONGER AND GUSTY WEST WINDS
THROUGH TONIGHT WITH GUSTS 45 TO 55 MPH IN THE MOUNTAINS AND
DESERTS. DRY AND WARMER FOR THE WEEKEND INTO NEXT WEEK WITH HIGH
TEMPERATURES RISING TO AROUND AVERAGE OVER THE WEEKEND AND ABOVE
AVERAGE FOR THE MIDDLE OF NEXT WEEK.
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
THIS MORNING...ISOLATED LIGHT SHOWERS CONTINUE, MAINLY OVER SAN
DIEGO COUNTY. SFC PRESSURE GRADIENTS REMAIN STRONGLY ONSHORE,
SUPPORTING WIND GUSTS OF 45-55 MPH IN THE WIND-FAVORED LOCATIONS
OF THE MTNS AND ADJACENT DESERTS.
THE WINDS WILL STRENGTHEN IN THE LOWER ELEVATIONS WEST OF THE
MTNS THIS AFTERNOON WITH GUSTS OF 30 TO 40 MPH NEAR THE COAST AND
25 TO 35 MPH IN THE INLAND EMPIRE. HIGH TEMPERATURES TODAY WILL BE
SEVERAL DEGREES LOWER THAN YESTERDAY AS COLDER AIR CONTINUES TO
FILTER IN FROM THE NORTHWEST. ISOLATED, MOSTLY LIGHT SHOWERS WILL
CONTINUE BETWEEN THE COAST AND THE MOUNTAINS TODAY, WITH
ADDITIONAL RAINFALL IN THE MOUNTAINS OF ONE-TENTH TO ONE-QUARTER
INCH AND SNOWFALL OF AROUND ONE INCH ABOVE 7000 FEET.
A REINFORCING SHORTWAVE EMBEDDED IN THE NORTHWEST FLOW ON THE BACK
SIDE OF THE MEAN TROUGH WILL MOVE THROUGH CA TONIGHT AND WEDNESDAY,
BRINGING ANOTHER ROUND OF SHOWERS WITH THE SNOW LEVEL FALLING TO
3000 TO 4000 FEET LATE TONIGHT AND RISING TO AROUND 4500 FEET FOR
WEDNESDAY AFTERNOON. ADDITIONAL RAINFALL AND LIQUID-EQUIVALENT
ABOVE THE SNOW LEVEL IS EXPECTED TO RANGE FROM ONE-TENTH INCH OR
LESS NEAR THE COAST TO ONE-QUARTER TO ONE-HALF INCH IN THE
MOUNTAINS WITH LOCALLY GREATER AMOUNTS. SNOWFALL OF 3 TO 5 INCHES
IS POSSIBLE, MOSTLY ABOVE 5000 TO 5500 FEET. THUNDERSTORMS ARE NOT
LIKELY BUT CAN'T BE RULED OUT AT THIS TIME.
A SECOND IMPULSE WILL BRING ANOTHER INCREASE IN SHOWER ACTIVITY
WEDNESDAY NIGHT INTO THURSDAY EVENING WITH MORE COLD AIR BRINGING
THE SNOW LEVEL DOWN TO 4000-4500 FEET FOR WEDNESDAY NIGHT. THE
SNOW LEVEL WILL RISE AGAIN TO 5000-5500 FEET FOR THURSDAY
AFTERNOON AND EVENING. ADDITIONAL RAINFALL AND LIQUID-EQUIVALENT
ABOVE THE SNOW LEVEL IS EXPECTED TO RANGE FROM ONE-TENTH INCH OR
LESS NEAR THE COAST TO TO AROUND ONE-QUARTER INCH IN THE MOUNTAINS
WITH LOCALLY GREATER AMOUNTS. SNOWFALL OF 3 TO 5 INCHES IS
POSSIBLE, MOSTLY ABOVE 5000 TO 5500 FEET WITH LOCALLY 5 TO 9
INCHES ON THE HIGHER PEAKS ABOVE 7500 FEET. THERE IS ALSO A SLIGHT
CHANCE OF THUNDERSTORMS FOR THURSDAY AFTERNOON.
THE DOMINANT LOW PRESSURE TROUGH OVER THE WESTERN STATES WILL BEGIN TO
MOVE EAST INTO THE PLAINS AND WEAKEN FOR FRIDAY AND SATURDAY. A
TRANSIENT HIGH PRESSURE RIDGE ALOFT WILL MOVE OVER CALIFORNIA FROM
THE WEST ON SUNDAY WITH A WEAK LOW PRESSURE SYSTEM MOVING QUICKLY
INLAND NORTH OF POINT CONCEPTION AROUND MONDAY. THERE WILL BE
WARMING FOR FRIDAY THROUGH SUNDAY, WITH HIGH TEMPERATURES RISING TO
AROUND AVERAGE OVER THE WEEKEND. THE LOW PRESSURE SYSTEM MOVING
INLAND THROUGH NORTHERN AND CENTRAL CALIFORNIA AROUND MONDAY WILL
BRING STRONGER ONSHORE FLOW TO SOUTHERN CALIFORNIA WITH SLIGHT
COOLING AND GUSTY WEST WINDS FOR THE MOUNTAINS AND DESERTS.
AVIATION
011630Z...COAST/VALLEYS/COASTAL MOUNTAIN SLOPES...LOW CLOUDS HAVE
LARGELY DEGRADED TO A SCT CUMULUS FIELD ACROSS THE COASTS AND VALLEYS
BASED AT 2000-2500FT MSL THIS MORNING. OCCASIONAL PERIODS OF BKN
CIGS ARE POSSIBLE IN THESE CU BUT WILL BE BRIEF. BKN-OVC LOW CLOUDS
CONTINUE IN THE AFTERNOON ALONG THE WEST-FACING COASTAL SLOPES WITH
VIS OBSCURATIONS IN FG/DZ. NORTHWEST WIND GUSTS TO 20-25 KTS PICKING
UP BY 18Z ACROSS THE COASTS AND VALLEYS, GRADUALLY WEAKENING AFTER
00Z THIS EVENING. LOW CLOUDS BASED AT 1500-2500 FEET MSL WILL
INCREASE AFTER 02Z, MAINLY IN SAN DIEGO COUNTY.
DESERT MOUNTAIN SLOPES/DESERTS...SCT-BKN CLOUDS AOA 15000 FEET MSL.
AREAS OF HIGH DESERT BKN CLOUDS 4000 FEET MSL. WESTERLY WINDS WILL
CONTINUE, INCREASING AFTER 20Z WITH GUSTS 35-55 KTS OVER THE RIDGES
AND IN WIND-PRONE MOUNTAIN PASSES, WITH GUSTS 25-35 KTS WITHIN THE
OPEN DESERTS. AREAS OF MODERATE UP/DOWNDRAFTS, INCLUDING LOCALIZED
LLWS AND ROTORS, IN LEE OF MOUNTAINS (I.E., VCNTY KPSP).
MARINE
WINDS INCREASE AND SEAS BUILD TODAY, WITH GALES AND VERY STEEP SEAS
IN THE OUTER WATERS AND HAZARDOUS WINDS AND SEAS IN THE INNER WATERS
THROUGH WEDNESDAY MORNING. WINDS AND SEAS DIMINISH SOME ON WEDNESDAY
BUT HAZARDOUS CONDITIONS PERSIST THROUGH WEDNESDAY EVENING IN THE
OUTER WATERS. CHECK THE GALE WARNING AND THE SMALL CRAFT ADVISORY
FOR DETAILS.
BEACHES
WHILE A 9-10FT 300 DEGREE NORTHWESTERLY SWELL APPROACHES LATER
TODAY, THE FAIRLY SHORT PERIOD OF 8-9 SECONDS KEEPS MAXIMUM WAVE
HEIGHTS TO AROUND 8-9 FEET. GIVEN THE NORTHWESTERLY DIRECTION, ONLY
WEST-NORTHWEST FACING BEACHES WILL FEEL THE EFFECTS OF THIS SWELL
AND ISLAND SHADOWING WILL LIKELY PLAY A ROLE. STILL, STRONG RIP
CURRENTS ARE EXPECTED ALONG ALL BEACHES THROUGH WEDNESDAY. SURF OF 3-
6 FEET EXPECTED ALONG ORANGE COUNTY BEACHES, AND LARGELY 4-7 FEET IN
SAN DIEGO COUNTY BEACHES BUT THE TRUE WNW FACING BEACHES COULD SEE
SETS TO 9 FEET. SURF DIMINISHES BY NOON WEDNESDAY.
SKYWARN
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.
SGX WATCHES/WARNINGS/ADVISORIES
CA...WIND ADVISORY UNTIL 2 AM PDT WEDNESDAY FOR ORANGE COUNTY COASTAL
AREAS-ORANGE COUNTY INLAND AREAS-SAN BERNARDINO AND
RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-SAN DIEGO COUNTY
COASTAL AREAS-SAN DIEGO COUNTY VALLEYS-SANTA ANA MOUNTAINS
AND FOOTHILLS.
WIND ADVISORY UNTIL 2 AM PDT WEDNESDAY FOR APPLE AND LUCERNE
VALLEYS-COACHELLA VALLEY-RIVERSIDE COUNTY MOUNTAINS-SAN
BERNARDINO COUNTY MOUNTAINS-SAN DIEGO COUNTY DESERTS-SAN
DIEGO COUNTY MOUNTAINS-SAN GORGONIO PASS NEAR BANNING.
PZ...SMALL CRAFT ADVISORY UNTIL 9 AM PDT WEDNESDAY FOR COASTAL WATERS
FROM SAN MATEO POINT TO THE MEXICAN BORDER AND OUT TO 10 NM.
SMALL CRAFT ADVISORY UNTIL 3 PM PDT THIS AFTERNOON FOR WATERS
FROM SAN MATEO POINT TO THE MEXICAN BORDER EXTENDING 10 TO
60 NM OUT INCLUDING SAN CLEMENTE ISLAND.
SMALL CRAFT ADVISORY FROM 9 AM TO 11 PM PDT WEDNESDAY FOR WATERS
FROM SAN MATEO POINT TO THE MEXICAN BORDER EXTENDING 10 TO
60 NM OUT INCLUDING SAN CLEMENTE ISLAND.
GALE WARNING FROM 3 PM THIS AFTERNOON TO 9 AM PDT WEDNESDAY FOR
WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER EXTENDING
10 TO 60 NM OUT INCLUDING SAN CLEMENTE ISLAND.
PUBLIC...PG
AVIATION/MARINE/BEACHES...MUNYAN
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