Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 292031
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
131 PM PDT TUE JUL 29 2014

.SYNOPSIS...
MID-LEVEL MOISTURE MAY CONTINUE TO RESULT IN THE NIGHT AND MORNING
FOG AND STRATUS BEING SOMEWHAT PATCHY ALONG THE COAST TONIGHT AND
TOMORROW. DRIER WEATHER WILL PREVAIL THROUGH THURSDAY...WITH THE
RETURN OF MONSOONAL MOISTURE POSSIBLE FOR FRIDAY INTO THE
WEEKEND...BRINGING BACK TO CHANCE FOR AFTERNOON MOUNTAIN AND DESERT
THUNDERSTORMS. SLOW WARMING IS EXPECTED INTO FRIDAY...FOLLOWED BY
SLOW COOLING THIS WEEKEND INTO EARLY NEXT WEEK AS LOWER PRESSURE
ALOFT MOVES IN. NIGHT AND MORNING STRATUS AND FOG...WILL CONTINUE
ALONG THE COAST AND SOMETIMES INTO THE WESTERN VALLEYS.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

HIGH CLOUDS ASSOCIATED WITH MOISTURE FROM POST-TROPICAL CYCLONE
HERNAN ARE INTRUDING INTO THE AREA THIS AFTERNOON...ACCORDING TO
VISIBLE SATELLITE. THE 12Z MIRAMAR SOUNDING SHOWS A DRIER...MORE
STABLE PROFILE THAN THAT OF 12Z YESTERDAY...AS PRECIPITABLE WATER IS
DOWN TO 1.47 INCHES...WITH NO SURFACE BASED CAPE AND A LIFTED INDEX
OF 4.9. ALTHOUGH THERE IS STILL A DECENT AMOUNT OF MOISTURE...THE
ATMOSPHERE IS JUST TOO STABLE...AND SO THUNDERSTORMS WERE REMOVED
FROM THE AFTERNOON FORECAST. THE REASON FOR THE DRYING IS THE FLOW
TURNING FROM THE SOUTH-SOUTHEAST YESTERDAY TO SOUTHWEST THIS
MORNING...WHICH IS DUE TO THE WEST-TO-EAST ORIENTED UPPER LEVEL
RIDGE NOW OVER NORTHERN MEXICO.

LOCAL WRF SHOWS STRATUS/FOG DEVELOPMENT TONIGHT/TOMORROW MORNING
BEING PATCHY AT BEST ALONG THE COAST...LIKELY DUE TO SOME
INTERFERENCE FROM UPPER LEVEL MOISTURE MOVING IN FROM HERNAN. MODELS
ARE IN GOOD AGREEMENT WITH THE BULK OF THIS MOISTURE STAYING TO OUR
WEST AND MOVING UP THROUGH CENTRAL CALIFORNIA TODAY THROUGH
TOMORROW. THUS...THE MOST WE SHOULD GET FROM THIS MOISTURE WILL BE
SOME HIGH CLOUDS AND POSSIBLY VIRGA.

DRYING SHOULD CONTINUE WEDNESDAY INTO THURSDAY...WITH SLIGHT WARMING
OCCURRING...RESULTING IN DAY-TIME HIGHS NEAR TO SLIGHTLY ABOVE
NORMAL. NIGHT AND MORNING STRATUS MAY STILL BE SOMEWHAT PATCHY ALONG
THE COAST. BY FRIDAY...THE RIDGE BECOMES ORIENTED IN MORE OF A
NORTH-TO-SOUTH FASHION ACROSS ARIZONA AND NEW MEXICO...RESULTING IN
SOUTHERLY FLOW RETURNING TO THE AREA AND SOME MONSOONAL MOISTURE
MOVING INTO THE REGION. BY SATURDAY...CHANCES FOR AFTERNOON/EARLY
EVENING THUNDERSTORMS OVER THE MOUNTAINS AND DESERTS RETURN TO THE
FORECAST WITH MOISTURE INCREASING. ON SUNDAY...THE ECMWF AND GEM
CONTINUE TO SHOW A POTENTIALLY POTENT WAVE OR UPPER LOW MOVING
ACROSS THE AREA...WHICH WOULD BRING GOOD CHANCES FOR ELEVATED
THUNDERSTORMS ACROSS THE MOUNTAINS AND DESERTS...WHILE THE GFS STILL
HAS A TROUGH DIGGING DOWN ALONG THE COAST...WITH SOUTHWEST FLOW
ALOFT BRINGING DRYING AND SUPPRESSING THE THUNDERSTORM THREAT. SINCE
THE ECMWF HAS BEEN SHOWING THIS FEATURE FOR AT LEAST THE PAST TWO
RUNS...AND SINCE THE GEM IS SHOWING IT AS WELL...HAVE ADDED
THUNDERSTORMS TO THE FORECAST FOR SUNDAY FOR THE MOUNTAINS...DESERTS
AND VALLEYS. THUNDERSTORMS MAY NEED TO BE ADDED TO THE COAST AND
COASTAL WATERS AT SOME POINT IF THE MODELS COME INTO BETTER
AGREEMENT WITH THIS FEATURE. NOCTURNAL CONVECTION MAY ALSO BE
POSSIBLE.

ALSO...LOOKS LIKE IT WILL COOL DURING THE WEEKEND DUE TO LOWER 500
MB HEIGHTS AND INCREASING CLOUD COVER...WITH TEMPERATURES NEAR TO
SLIGHTLY BELOW NORMAL...AND NIGHT AND MORNING STRATUS CONTINUING
ALONG THE COAST AND POSSIBLY INTO THE WESTERN VALLEYS AT TIMES. THE
GFS AND ECMWF SHOW SIGNIFICANT DRYING OCCURRING EARLY NEXT WEEK.

&&

.AVIATION...
292015Z...COASTS/VALLEYS...OCCASIONAL SCT-BKN CLOUDS AT OR ABOVE
15000 FT MSL THROUGH THIS EVENING. PATCHY STRATUS WILL DEVELOP OVER
THE COASTAL WATERS TONIGHT WITH BASES 800-1200 FT MSL AND TOPS 1400
FT MSL. THIS LOW CLOUD DECK WILL PUSH INLAND 5-10 SM AND COULD REACH
KSNA...KCRQ...AND KSAN FOR A TIME BETWEEN 30/0900Z-1500Z. VIS MAY
DROP TO BETWEEN 3-5 SM WHERE CLOUDS NEAR TERRAIN ON THE COASTAL
MESAS.

MOUNTAINS/DESERTS...SCT-BKN CLOUDS AT/ABOVE 15000 FT MSL AND
UNRESTRICTED VIS THROUGH THIS AFTERNOON...BECOMING FEW-SCT TONIGHT.

&&

.MARINE...
115 PM PDT...NO HAZARDOUS MARINE WEATHER EXPECTED THROUGH SATURDAY.

&&

.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...HARRISON
AVIATION/MARINE...JT





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