NWS Forecast Discussion
000 FXUS66 KSGX 031603 AFDSGX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 900 AM PDT FRI SEP 3 2010 .SYNOPSIS...HOT DAYS INLAND TODAY AND SATURDAY. CLEAR SKIES EXCEPT FOR MARINE LAYER COASTAL LOW CLOUDS AND FOG DURING THE NIGHTS AND MORNINGS. AN UPPER LEVEL LOW PRESSURE TROUGH WILL BRING MUCH COOLER WEATHER WITH A DEEPER MARINE LAYER...AND BREEZY CONDITIONS IN THE MOUNTAINS AND DESERTS AT TIMES NEXT WEEK. && .DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO... ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES. CLEAR SKIES THIS MORNING EXCEPT FOR LOW CLOUDS AND PATCHY DENSE FOG IN THE COASTAL AREAS. THE MORNING SOUNDING FROM NKX SHOWED A STRONG INVERSION AT ABOUT 900 FEET WITH WESTERLY WINDS AND DRY AIR ABOVE. SFC PRESSURE GRADIENTS REMAIN ONSHORE TO THE E WITH ABOUT 5 MB SAN-IPL. A STRONG HIGH PRESSURE RIDGE ALOFT WILL CONTINUE HOT WEATHER INLAND THROUGH SATURDAY. MAX TEMPS INLAND WILL BE ABOUT 7 TO 14 DEGREES ABOVE SEASONAL AVERAGES TODAY AND SATURDAY. ONSHORE FLOW AND THE MARINE INFLUENCE WILL MODERATE MAX TEMPS NEAR THE COAST. SUBSIDENCE FROM THE HIGH ALOFT WILL KEEP THE MARINE LAYER SHALLOW THROUGH SATURDAY. LOW CLOUDS AND LOCALLY DENSE FOG DURING THE NIGHTS AND MORNINGS WILL MOSTLY BE CONFINED TO THE COASTAL AREAS. STRATUS MAY BE SLOW TO CLEAR FROM THE BEACHES DUE TO THE STRONG INVERSION. THE MARINE LAYER WILL DEEPEN A LITTLE SATURDAY NIGHT AND SUNDAY MORNING AS THE UPPER LEVEL RIDGE BEGINS TO WEAKEN IN RESPONSE TO A LOW PRESSURE TROUGH MOVING INTO THE PAC NW. A COOLING TREND WILL BEGIN SUNDAY WITH MAX TEMPS INLAND ABOUT 10 DEGREES LOWER THAN ON SATURDAY. A SHORTWAVE WILL MOVE EWD THROUGH THE MEAN UPPER LEVEL TROUGH INTO THE NRN ROCKIES ON MONDAY WITH LITTLE CHANGE IN CONDITIONS...FOLLOWED BY A SECOND SHORTWAVE WHICH WILL DEEPEN THE TROUGH OVER THE WEST COAST TUE THROUGH WED. THIS WILL BRING CONSIDERABLE COOLING WITH TEMPERATURES WELL BELOW SEASONAL AVERAGES. THE MARINE LAYER WILL DEEPEN TO THE EXTENT THAT LOW CLOUDS AND FOG WILL EXTEND INLAND TO THE COASTAL SLOPES DURING THE NIGHTS AND MORNINGS. AN INTERMITTENT COASTAL EDDY WILL DEVELOP. STRONGER ONSHORE FLOW WILL CAUSE LOCAL BREEZY CONDITIONS IN THE MOUNTAINS AND DESERTS AT TIMES. SLIGHTLY WARMER THURSDAY AND FRIDAY AS THE TROUGH MOVES E...ALTHOUGH SOCAL WILL LIKELY REMAIN UNDER CYCLONIC FLOW ALOFT. && .AVIATION... 031500Z...SHALLOW MARINE LAYER ABOUT 800 FT. BASES AROUND 100 TO 300 FT MSL. WIDESPREAD VSBY ONE QUARTER MILE ALONG THE COAST THIS MORNING. EXPECT VSBY TO MOSTLY 3-5SM IN HAZE AND BECOME MOSTLY SCATTERED AT 500 FT MSL BY 16Z. EXPECT MARINE LAYER TO LOWER MORE TONIGHT WITH DENSE FOG POSSIBLE ALONG THE COAST LATE TONIGHT THROUGH SAT MORNING WITH FOG MOVING IN AROUND 09Z. && .SGX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...PG AVIATION...WHITLOW
NWS SGX Office Area Forecast Discussion