Area Forecast Discussion
Issued by NWS San Diego, CA

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000 FXUS66 KSGX 060347 AFDSGX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 845 PM PDT TUE MAY 5 2015 .SYNOPSIS... A COLD LOW PRESSURE TROUGH OVER THE PACIFIC NORTHWEST WILL BRING COOL WEATHER...A DEEP MARINE LAYER AND GUSTY MOUNTAIN AND DESERT WINDS THIS WEEK. DRIZZLE IS POSSIBLE LATE TONIGHT AND EARLY WEDNESDAY WEST OF THE MOUNTAINS. SHOWERS ARE MOST LIKELY THURSDAY AND FRIDAY WHEN THE TROUGH MOVES ACROSS SOUTHERN CALIFORNIA. DRY WEATHER WILL RETURN SATURDAY FOLLOWED BY WARMER WEATHER SUNDAY AND MONDAY UNDER WEAK HIGH PRESSURE ALOFT. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... A COLD UPPER LOW OVER THE PACIFIC NORTHWEST WILL BRING A PERIOD OF COOL...UNSETTLED WEATHER TO SO-CAL THROUGH FRIDAY. WEDNESDAY WILL BE ANOTHER COOL DAY WITH A DEEP MARINE LAYER IN PLACE...PERHAPS DEEP ENOUGH FOR DRIZZLE WEST OF THE MOUNTAINS IN THE MORNING. IT WILL BE ANOTHER WINDY DAY IN THE MOUNTAINS AND DESERTS WEDNESDAY...BUT THE STRONGEST WINDS WILL NOT SURFACE UNTIL THURSDAY AND THURSDAY NIGHT WHEN A 90KT 300 MB JET STREAM TRACKS ACROSS SOUTHERN CALIFORNIA. A WIND ADVISORY IS IN EFFECT FOR THE DESERTS DURING THIS TIME. TEMPERATURES WILL BE SEVERAL DEGREES BELOW AVERAGE WEDNESDAY THROUGH FRIDAY. THERE IS ALSO A PRETTY GOOD CHANCE FOR SHOWERS WITH THIS SYSTEM THURSDAY AND FRIDAY AS THE AIRMASS DESTABILIZES BENEATH THE COLD UPPER LOW WHERE 500 MB TEMPS FALL TO BETWEEN -20 AND -25C. BOUNDARY LAYER MOISTURE IN THE LOWEST 8000 FEET WILL BE NEAR SATURATION AND PWATS INCREASE TO 0.80". THIS MOISTURE AND STRONG INSTABILITY SHOULD SUPPORT SHOWERS AND THUNDERSTORMS THURSDAY AFTERNOON THROUGH FRIDAY MORNING. SNOW LEVELS WILL BE QUITE LOW FOR EARLY MAY...DOWN TO AROUND 5500 FEET. PRECIPITATION AMOUNTS WILL BE VARIABLE. SOME AREAS COULD SEE AN OVER AN INCH OF RAIN IN THE HEAVIEST SHOWERS...BUT MOST AREAS WILL SEE AROUND A QUARTER-INCH. THE PRECIP WILL SHIFT EAST FRIDAY NIGHT LEAVING BEHIND A COOL BREEZY DAY SATURDAY IN NORTHWEST FLOW ALOFT. MUCH WARMER SUNDAY AND MONDAY WITH WEAK RIDGING ALOFT. && .AVIATION... 060300Z...COAST/VALLEYS... LOW CLOUDS...WITH BASES BETWEEN 3000-3500 FT MSL AND TOPS TO 4500 FT MSL...WILL DEVELOP ALONG THE COAST THIS EVENING...AND PUSH INLAND TO THE COASTAL MTN SLOPES. LOW CLOUDS MAY OBSCURE TERRAIN IN THE FOOTHILLS. STRATUS WILL BECOME SCT/FEW LATE WEDNESDAY MORNING...THEN BECOME BKN/OVC WEDNESDAY EVENING WEST OF THE MTNS WITH SIMILAR TOPS AND BASES. MTNS/DESERTS..WESTERLY WIND GUSTS TO 35 KT WILL PRODUCE MODERATE UDDFS/LLWS OVER AND EAST OF THE MTNS THROUGH 15Z WEDNESDAY. ISOLATED STRONGER GUSTS TO 50 KT ARE LIKELY THROUGH AND BELOW THE SAN GORGONIO PASS. OTHERWISE...MOSTLY SKC THROUGH WEDNESDAY EVENING. && .MARINE... 900 PM...A DISTURBANCE MOVING ACROSS THE REGION WILL CREATE A CHANCE OF THUNDERSTORMS AND ISOLATED CLOUD-TO-WATER LIGHTNING STRIKES OVER THE COASTAL WATERS THU NIGHT INTO FRI MORNING. OTHERWISE...NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH SUNDAY. && .BEACHES... 900 PM...SURF WILL LOWER OVERNIGHT FROM HIGH TO ELEVATED AS THE SOUTHERLY SWELL CONTINUES TO DECREASE. ISOLATED SETS TO 8-10 FT WILL BE POSSIBLE WEDNESDAY ALONG SOUTHERLY FACING BEACHES. STRONG RIP AND LONG SHORE CURRENTS WILL CONTINUE THROUGH THE END OF THE WEEK AND THE SWELL DECREASES. && .SKYWARN... SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...WIND ADVISORY FROM 4 PM WEDNESDAY TO 3 AM PDT FRIDAY FOR APPLE AND LUCERNE VALLEYS-SAN DIEGO COUNTY DESERTS-SAN GORGONIO PASS NEAR BANNING. HIGH SURF ADVISORY UNTIL 11 PM PDT THIS EVENING FOR ORANGE COUNTY COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS. PZ...NONE. && $$ PUBLIC...MOEDE AVIATION/MARINE/BEACHES...JJT

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