Area Forecast Discussion
Issued by NWS San Diego, CA

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000 FXUS66 KSGX 261525 AFDSGX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 825 AM PDT TUE MAY 26 2015 .SYNOPSIS... A SEASONALLY DEEP MARINE LAYER WILL CONTINUE TO BRING AREAS OF CLOUDS...FOG...AND SOME PATCHY DRIZZLE AT TIMES WEST OF THE MOUNTAINS THROUGH WEDNESDAY...WHILE FAIR SKIES AND WARM CONDITIONS PREVAIL OVER THE MOUNTAINS AND DESERTS. BETTER CLEARING IS EXPECTED WEST OF THE MOUNTAINS FOR THE LATTER HALF OF THE WEEK AS HIGH PRESSURE BUILDS ALOFT AND THE MARINE LAYER SHRINKS BACK TOWARD THE COAST. COASTAL AREAS WILL REMAIN MODERATE THROUGH THE WEEKEND... WHILE INLAND AREAS BECOME QUITE WARM. COOLER THROUGH THE FIRST WEEK OF JUNE AS ONSHORE FLOW AND THE MARINE LAYER INCREASE. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... ONCE AGAIN THIS MORNING MARINE STRATUS WAS EXTENSIVE AND THERE WERE NUMEROUS REPORTS OF DRIZZLE AT 7 AM PDT. SATELLITE IMAGERY FROM EARLY THIS MORNING SHOWED A NEARLY SOLID CLOUD LAYER COVERING THE CA BIGHT...EXTENDING INLAND TO THE COASTAL SLOPES. THE 12Z MIRAMAR SOUNDING HAD A 1500 FT DEEP NEARLY SATURATED LAYER TOPPED BY A WEAK 4 DEGREE C INVERSION BASED NEAR 3200 FT MSL. SURFACE PRESSURE GRADIENTS WERE 3-5 MBS ONSHORE TO THE DESERTS BUT ANY WIND GUST REPORTS OVER 20 MPH WERE CONFINED TO THE SAN GORGONIO PASS AND THE I- 8 GRADE INTO IMPERIAL COUNTY. LITTLE CHANGE IN THE CURRENT WEATHER PATTERN THROUGH WED WITH A DEEP MARINE LAYER WEST OF THE MTS...AND FAIR SKIES ALONG THE HIGHER ELEVATIONS OF THE MTS AND ACROSS THE DESERTS. OUR LOCAL HIRES 06Z WRFEMS RUN KEEPS A DEEP SATURATED LAYER AT KSAN THROUGH WED WITH LITTLE CLEARING INDICATED...SO GIVEN THE TIME OF YEAR...THIS SEEMS LIKE A REASONABLE FORECAST. ALSO...WITH THE DEEP MOIST LAYER... AREAS OF DRIZZLE ARE LIKELY TO REDEVELOP...MAINLY OVERNIGHT AND MORNINGS. EXPECT BETTER CLEARING OVER THE INLAND VALLEYS TODAY... WITH A FEW BREAKS POSSIBLE NEAR THE COAST LATE...OTHERWISE CLOUDS WILL PREVAIL. SPLIT FLOW CONTINUES OVER THE EASTPAC TODAY. THE SOUTHERN BRANCH WILL STEER ANOTHER TROUGH INLAND ACROSS THE BAJA PENINSULA ON WED. THIS WILL LOWER HEIGHTS ONLY SLIGHTLY ACROSS SOCAL...BUT SHOULD BE ENOUGH TO MAINTAIN THE STRATUS W OF THE MTS. ONCE THIS PASSES... HEIGHTS/THICKNESS WILL INCREASE INTO THE WEEKEND AS A RIDGE SLOWLY BUILDS EAST OFF THE PACIFIC. THIS WILL PUSH DAYTIME HIGHS SEVERAL DEGREES ABOVE AVERAGE INLAND...AND BRING MORE HOURS OF SUNSHINE TO COASTAL AREAS. THE RIDGE MOVES EAST AND IS REPLACED BY A WEAK TROUGH EARLY NEXT WEEK. THE TROUGH IS WEAK...BUT LOOKS SUFFICIENT TO MAINTAIN AT LEAST A ZONAL FLOW ALOFT...AND ONSHORE FLOW AT THE SURFACE ACROSS CA. THIS WILL HELP TO REBUILD THE MARINE LAYER AND PROVIDE SLIGHTLY COOLER CONDITIONS INLAND MUCH OF NEXT WEEK. && .AVIATION... 261519...COAST/VALLEYS...OVC-BKN STRATUS...WITH BASES AROUND 1500-2000 FT MSL...TOPS 3000-4000 FT MSL...LOCAL VIS OF 3-5 SM...PATCHY DRIZZLE...AND MTN OBSCURATION OF LOWER COASTAL SLOPES...WILL LIKELY CONTINUE FOR THE MOST PART THROUGH 27/0200 UTC...WITH ONLY SLIGHT CLEARING POSSIBLE FOR THE COAST AND A LITTLE BETTER CLEARING POSSIBLE IN THE VALLEYS. MARINE LAYER INVERSION OF 4 DEG C. 27/0200-1500 UTC...MOSTLY OVC STRATUS...WITH SIMILAR BASES AND TOPS TO THIS MORNING. FORECAST CONFIDENCE IS MODERATE. MTNS/DESERTS...UNRESTRICTED VIS THROUGH WEDNESDAY MORNING. FEW-SCT CLOUDS AOA 20000 FT MSL BECOMING SCT-BKN AFTER 27/0300 UTC. && .MARINE... 819 AM...NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH SATURDAY NIGHT. && .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...JAD AVIATION/MARINE...HARRISON

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