Area Forecast Discussion
Issued by NWS San Diego, CA

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000 FXUS66 KSGX 302038 AFDSGX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 138 PM PDT MON MAR 30 2015 .SYNOPSIS... A FEW UPPER-LEVEL TROUGHS MOVING BY TO OUR NORTH WILL HELP DEEPEN THE MARINE LAYER...CREATE SLIGHTLY COOLER WEATHER AND DEVELOP BREEZY WESTERLY WINDS IN THE MOUNTAINS AND DESERTS THROUGH MID WEEK. WEAK OFFSHORE FLOW WILL CREATE WARMING AND PUSH THE MARINE LAYER OFF THE COAST ON FRIDAY...WITH GUSTY NORTHEAST WINDS NEAR THE COASTAL FOOTHILLS. NEXT WEEKEND...A LOW PRESSURE SYSTEM DEVELOPING OVER THE EASTERN PACIFIC WILL DEVELOP SLIGHTLY COOLER WEATHER...A RETURN OF THE MARINE LAYER...AND BREEZY WESTERLY WINDS IN THE MOUNTAINS AND DESERTS. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... THE 30/1200 UTC ECMWF AND GFS ARE IN RELATIVELY GOOD AGREEMENT THROUGH THE END OF THE WORK WEEK. AT 1 PM PDT...WATER VAPOR SATELLITE IMAGERY DISPLAYED AN UPPER- LEVEL LOW AROUND 450 MILES S OF SAN DIEGO...AND A WEAK UPPER-LEVEL RIDGE OFF THE COAST OF SW CA. VISIBLE SATELLITE SHOWED MOSTLY CLEAR SKIES ACROSS THE CWA. A FEW TROUGHS MOVING BY TO OUR NORTH THIS WEEK WILL LOWER HIGH TEMPERATURES TO NEAR NORMAL BY THURSDAY...CREATE BREEZY WESTERLY WINDS IN THE MOUNTAINS AND DESERTS...AND DEEPEN THE MARINE LAYER THROUGH MID WEEK. ISOLATED WESTERLY WIND GUSTS TO 50 MPH WILL BE POSSIBLE OVER THE MOUNTAINS AND DESERTS TUESDAY AND WEDNESDAY NIGHTS. NIGHT AND MORNING LOW CLOUDS/FOG WILL PUSH INTO THE FAR INLAND VALLEYS BY WEDNESDAY MORNING. SURFACE HIGH PRESSURE BUILDING OVER THE GREAT BASIN AND SURFACE LOW PRESSURE OFF THE COAST WILL CREATE WEAK OFFSHORE FLOW AND SLIGHTLY WARMER WEATHER FOR THE COAST AND VALLEYS ON FRIDAY. AN OFFSHORE SURFACE PRESSURE GRADIENT AROUND -14 MB FROM SAN DIEGO TO SALT LAKE CITY WILL CREATE ISOLATED NORTHEASTERLY WIND GUSTS TO 45 MPH THROUGH AND BELOW MOUNTAIN PASSES AND CANYONS FRIDAY MORNING. THESE WINDS WILL HELP TO PUSH THE MARINE LAYER CLOUDS OFF THE COAST THURSDAY NIGHT. HIGH TEMPERATURES OVER MOST COASTAL AND VALLEY AREAS WILL BE RISE INTO THE 80S...WITH 70S ALONG THE IMMEDIATE COAST. ONSHORE FLOW WILL QUICKLY RETURN NEXT WEEKEND AS A TROUGH APPROACHES FROM THE WEST...LOWERING HIGH TEMPERATURES TO SLIGHTLY ABOVE NORMAL FOR THIS TIME OF YEAR AND REDEVELOPING THE MARINE LAYER BY SUNDAY MORNING. BREEZY WESTERLY WINDS...WITH LOCAL GUSTS NEAR 50 MPH...WILL BE POSSIBLE LATE SUNDAY INTO MONDAY OVER PORTIONS OF THE MOUNTAINS AND DESERTS. && .AVIATION... 302022Z...COAST/VALLEYS...THROUGH 31/0100 UTC...MOSTLY UNRESTRICTED VIS AND SKC. 31/0100-1500 UTC...STRATUS GRADUALLY DEVELOPING 15-20 SM INLAND...WITH BASES 800-1100 FT MSL...TOPS 1300-1600 FT MSL...AND LOCAL VIS AOB 1 SM OVER HIGHER COASTAL TERRAIN AND INLAND MESAS. MARINE LAYER INVERSION OF ABOUT 6 DEGREES EXPECTED. FORECAST CONFIDENCE ON STRATUS OCCURRENCE AT KSAN...KCRQ AND KSNA IS HIGH...WITH MODERATE CONFIDENCE IN TIMING AND BASE/TOP HEIGHTS. CHANCE THAT STRATUS/FOG WILL MAKE IT INTO KONT FOR A FEW HOURS...BUT CONFIDENCE IS LOW. STRATUS/FOG CLEARING TO THE COASTAL WATERS 31/1500-1800 UTC. DESERTS/MTNS...UNRESTRICTED VIS THROUGH TUESDAY MORNING. SKC...BECOMING SCT CLOUDS AOA 20000 FT MSL AFTER 31/0600 UTC. && .MARINE... 122 PM...STEEP SEAS OF 10 FEET AND NORTHWEST WIND GUSTS TO 25 KT WILL BE POSSIBLE ON THURSDAY OVER THE OUTER WATERS AS A TROUGH MOVES INLAND NORTH OF THE AREA. THIS COULD RESULT IN HAZARDOUS CONDITIONS TO SMALL CRAFT. FORECAST CONFIDENCE IS MODERATE. OTHERWISE...NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH FRIDAY. && .BEACHES... A 4-5 FOOT/17 SECOND SOUTH SWELL IS BRINGING WIDESPREAD 4-6 FOOT SURF TO ORANGE COUNTY BEACHES...AND SOME SAN DIEGO COUNTY BEACHES... THIS AFTERNOON. SOME BEACHES IN ORANGE COUNTY HAVE REPORTED 5-7 FOOT SURF AS WELL. THESE SURF CONDITIONS...ALONG WITH A HIGH RISK OF STRONG RIP CURRENTS...WILL CONTINUE THIS AFTERNOON...WITH THE SWELL AND SURF FALLING TONIGHT INTO TUESDAY. WAVE WATCH 3 INDICATES AN 8 FOOT/11 SECOND WEST-NORTHWEST SWELL MOVING IN ON WEDNESDAY...WITH A 10 FOOT/11 SECOND WEST-NORTHWEST SWELL THEN OCCURRING ON THURSDAY. ALTHOUGH THE PERIOD ON THESE SWELLS WILL BE SOMEWHAT SHORT...THE SWELL HEIGHTS WILL BE LARGE ENOUGH TO BRING AT LEAST 4-6 FOOT SURF AND AN INCREASED RISK OF RIP CURRENTS. && .SKYWARN... SKYWARN ACTIVATION WILL NOT BE NEEDED TODAY. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...JJT AVIATION/MARINE/BEACHES...HARRISON

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