Area Forecast Discussion
Issued by NWS San Diego, CA

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000 FXUS66 KSGX 310451 AFDSGX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 930 PM PDT WED JUL 30 2014 .SYNOPSIS... FAIR WEATHER WILL PREVAIL THROUGH THURSDAY NIGHT WITH PATCHY NIGHT AND MORNING LOW CLOUDS AND FOG NEAR THE COAST. TEMPERATURES WILL CONTINUE TO BE A LITTLE ABOVE SEASONAL NORMALS IN MOST AREAS. MOISTURE WILL INCREASE FROM THE SOUTHEAST FRIDAY AND SATURDAY AND COMBINE WITH A WEAK LOW PRESSURE SYSTEM ALOFT TO BRING INCREASING CHANCES OF THUNDERSTORMS OVER THE MOUNTAINS AND DESERTS...MAINLY IN THE AFTERNOONS AND EVENINGS. A FEW THUNDERSTORMS COULD STRAY WEST INTO THE VALLEYS...MAINLY SATURDAY. A FEW THUNDERSTORMS WILL LINGER SUNDAY...THEN FAIR WEATHER WILL RETURN MONDAY THROUGH WEDNESDAY OF NEXT WEEK. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... SKIES WERE MOSTLY CLEAR EXCEPT FOR A FEW PATCHES OF STRATUS FORMING ALONG THE BEACHES. MOISTURE FROM THE REMNANTS OF HERNAN WAS MOSTLY NORTH OF OUR AREA AS THAT HELPED TO PRODUCE THUNDERSTORMS THIS AFTERNOON OVER CENTRAL CALIFORNIA...INCLUDING THE SIERRA...THOUGH NONE FORMED OVER OUR FORECAST AREA TODAY. PATCHY STRATUS WILL OCCUR NEAR THE COAST OVERNIGHT...WITH SOME FOG POSSIBLE LATE OVER HIGHER COASTAL TERRAIN AND THE SAN DIEGO COUNTY MESAS...THOUGH ANY DENSE FOG SHOULD BE QUITE LOCAL. THE TEMP PROFILE WILL BE SIMILAR THU...SO ANOTHER HOT DAY WILL OCCUR INLAND...WITH LOWER DESERT TEMPS AS HIGH AS AROUND 115. MOISTURE ALOFT WILL GRADUALLY INCREASE THE NEXT FEW DAYS. 00Z NKX SOUNDING SHOWED 1.21 IN OF PRECIPITABLE WATER...SIMILAR TO 24 HOURS AGO...AND NOAA GPS PW SENSORS SHOW ONLY SLIGHTLY HIGHER VALUES IN THE LOWER DESERTS. THE MCS OVER SOUTHERN SONORA COULD POTENTIALLY PRODUCE SOME SOUTHEAST-TO-NORTHWEST FLOW FOR THU MORNING...AND IF THIS IS STRONG ENOUGH...THEN FUTURE SHIFTS MIGHT RECONSIDER THUNDERSTORM CHANCES FOR THU. HOWEVER...THE MOST LIKELY SCENARIO IS FOR ENOUGH MOISTURE IN THE 700-500 MB LAYER AND SURFACE BASED INSTABILITY FOR SCATTERED TSTORMS FRIDAY. MODELS HAVE BEEN SHOWING A WEAK UPPER LOW MOVING FROM SOUTHEAST TO NORTHWEST INTO SOUTHEASTERN CALIFORNIA AROUND SATURDAY NIGHT OR SUNDAY. MODELS ARE TYPICALLY LOW-CONFIDENCE WITH THIS KIND OF UPPER LOW IN SUMMER...BUT IT WOULD HAVE THE POTENTIAL TO CREATE DYNAMICS TO COMBINE WITH MOISTURE AND SOME ELEVATED CAPE AND PRODUCE THUNDERSTORMS OUTSIDE OF THE NORMAL MTN/DESERT LOCATIONS AND OUTSIDE THE NORMAL AFTERNOON/EVENING TIME FRAMES. MODELS HAVE TRENDED A BIT TO THE EAST IN RECENT RUNS...SO CHANCES OF COASTAL THUNDERSTORMS DO NOT LOOK HIGH ENOUGH TO PUT IN THE FORECAST...BUT INLAND VALLEYS COULD HAVE A STRAY THUNDERSTORM. RIGHT NOW...SATURDAY LOOKS LIKE THE BEST DAY FOR THUNDERSTORMS DUE TO THE BEST MOISTURE AS MOISTURE DECREASES A BIT SUNDAY. SOMEWHAT LOWER TEMPS OVER THE WEEKEND IN THE DESERTS WILL BE OFFSET BY THE HIGHER HUMIDITY WHICH WILL KEEP DAYTIME HEAT INDEX VALUES SIMILAR TO THOSE OF TODAY OR THURSDAY. DRIER WEST FLOW DEVELOPS AROUND MONDAY AS THE HIGH BUILDS A BIT OVER NORTHERN MEXICO AND SOME TROUGHING DEVELOPS OVER THE INTERIOR WEST...PARTLY FROM THAT UPPER LOW FROM THE WEEKEND. WEAK UPPER LOWS MOVING BY THE NORTH NEXT WEEK SHOULD MAINTAIN THE WEST FLOW THROUGH AT LEAST WED OR THU AND KEEP THE REGION DRY...AND HAVE A PATTERN CONDUCIVE TO NIGHT AND MORNING STRATUS NEAR THE COAST. TEMPS WILL BE MOSTLY SEASONAL. && .AVIATION... 310330Z...COASTS/VALLEYS...STRATUS WITH BASES 800-1000 FT MSL AND TOPS 1200 FT MSL WILL DEVELOP OVER THE COASTAL WATERS TONIGHT. THIS PATCHY LOW CLOUD DECK WILL MOVE INLAND 5-10 SM BETWEEN 03/0900-1400Z...POSSIBLY AFFECTING KSNA...KCRQ...KSAN. VISIBILITY MAY BE LOCALLY REDUCED TO 1 MILE OR LESS WHERE THE CLOUDS INTERSECT THE TERRAIN ON THE LOWER COASTAL MESAS. CONFIDENCE OF TIMING AND COVERAGE OF STRATUS IS LOW. THE LOW CLOUDS WILL ERODE TO THE BEACHES BY 31/1500Z. ANOTHER STRATUS DECK...SLIGHTLY DEEPER...WILL MOVE FROM THE COAST INLAND THURSDAY NIGHT AFT 01/0900Z. MOUNTAINS/DESERTS...SKC CONDS WITH LIGHT TO MODERATE DIURNALLY DRIVEN WINDS. && .MARINE... 900 PM PDT...NO HAZARDOUS MARINE WEATHER EXPECTED THROUGH SUNDAY. && .SKYWARN... SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS. && .SGX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...MAXWELL AVIATION/MARINE...JT

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