Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 252015
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
115 PM PDT FRI JUL 25 2014

.SYNOPSIS...
HIGH PRESSURE TO THE EAST WILL BRING SEASONALLY WARM SUMMER WEATHER
THROUGH NEXT WEEK. MONSOONAL MOISTURE WILL BRING PERIODS OF ISOLATED
TO SCATTERED THUNDERSTORMS THIS WEEKEND...MAINLY OVER THE MOUNTAINS
IN THE AFTERNOONS AND EVENINGS. THE MARINE LAYER WILL KEEP COASTAL
AREAS COOLER WITH AREAS OF NIGHT AND MORNING LOW CLOUDS AND FOG. THE
MARINE LAYER WILL BECOME MORE SHALLOW NEXT WEEK WITH LESS NIGHT AND
MORNING LOW CLOUDS.

&&

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

SCATTERED THUNDERSTORMS...WHICH DEVELOPED EARLY THIS MORNING...
REMAIN OVER PORTIONS OF THE CWA AT MIDDAY...BUT WERE SHIFTING TO
NORTHERN AREAS AT 1 PM PDT. RAINFALL AMOUNTS HAVE BEEN MOSTLY LIGHT
WEST OF THE MOUNTAINS...HOWEVER HEAVIER AMOUNTS WERE OCCURRING ALONG
THE DESERT SLOPES...IN THE COACHELLA VALLEY...AND IN THE MOUNTAINS
WHERE MORE MOISTURE WAS AVAILABLE. ONSHORE SFC PRESSURE
GRADIENTS WERE RUNNING 3-5 MBS...WITH MOSTLY LIGHT WINDS REPORTED
THROUGH NOON.

A HEAT ADVISORY REMAINS IN EFFECT FOR THE LOWER DESERTS TODAY...
MAINLY DUE TO THE INCREASE IN HUMIDITY AS MAX TEMPS WILL NOT BE AS
HIGH. CONTINUED SEASONALLY WARM TO HOT INLAND THROUGH THE WEEKEND.

THE STRONG SUBTROPICAL HIGH WILL REMAIN CENTERED OVER NEW MEXICO
THROUGH EARLY NEXT WEEK. SOUTH TO SE FLOW ALOFT AROUND THE HIGH WILL
CONTINUE TO STEER MONSOONAL MOISTURE AND POCKETS OF WEAK TO MODERATE
INSTABILITY OVER SOCAL THROUGH THE WEEKEND. MOST OF THE MOISTURE IS
EXPECTED TO BE ABOVE 10K FT...ALTHOUGH A LOW-LEVEL SURGE OF MOISTURE
UP THE IMPERIAL AND COACHELLA VALLEYS HAS ADDED TO THE PW. GPS
ESTIMATES OVER THE LOWER DESERTS HAVE CLIMBED TO AROUND 2 INCHES.
THIS WILL INCREASE THE POTENTIAL FOR LOCAL FLASH FLOODING IF CELLS
TRAIN OVER THE SAME SPOT.

FARTHER TO THE WEST...THE MAIN THREAT FROM ANY T-STORMS WILL BE THE
OCCASIONAL CLOUD-TO-GROUND LIGHTNING STRIKE AND GUSTY DOWNDRAFT
WINDS AS MOISTURE AND INSTABILITY SHOULD REMAIN CONCENTRATED ABOVE
10K FT. NOCTURNAL THUNDERSTORMS CANNOT BE RULED OUT ANYWHERE LATE
TONIGHT AND EARLY SAT MORNING DUE TO ANOTHER AREA OF ELEVATED
INSTABILITY EXPECTED FROM ANOTHER WEAK EASTERLY WAVE...BUT SHOULD BE
ISOLATED. THE MAIN THUNDERSTORM THREAT WILL BE IN THE MOUNTAINS EACH
AFTERNOON/EARLY EVENING.

UPPER-LEVEL WINDS WILL BECOME SW EARLY NEXT WEEK WITH SOME DRYING
AND A REDUCTION IN THE THUNDERSTORM THREAT. ANOTHER PUSH OF
MONSOONAL MOISTURE COULD DEVELOP LATER NEXT WEEK ACCORDING TO THE
LATEST GFS RUN BUT THE 00Z ECMWF LOOKS DRIER SO UNCERTAINTY
INCREASES SUBSTANTIALLY IN THE EXTENDED PERIOD.

FOR THE COAST...ONSHORE FLOW SHOULD MAINTAIN A SHALLOW MARINE LAYER
WITH AREAS OF NIGHT AND MORNING LOW CLOUDS AND FOG. HIRES MODELS
SHOW THE EDDY CONTINUING THROUGH SAT...THEN WEAKENING SO EXPECT THE
MARINE LAYER TO DECREASE...BUT MAINTAIN OVER COASTAL AREAS NEXT
WEEK.

&&

.AVIATION...
252000Z...COAST/VALLEYS...ISOLATED SHOWERS/THUNDERSTORMS WILL MOVE
NORTH MAINLY OVER NW SAN DIEGO COUNTY AND THE INLAND EMPIRE THROUGH
02Z. KONT WILL LIKELY REMAIN WEST OF THE PRECIP. SOME STRATUS WILL
OCCUR TONIGHT ALONG THE COAST AFTER 06Z...THOUGH TIMING IS SOMEWHAT
LOW CONFIDENCE. BASES WILL BE 1200-1500 FT MSL WITH TOPS TO 1700 FT
MSL. CLEARING SHOULD OCCUR IN MOST AREAS BY 17Z SAT...THOUGH THERE
IS A SMALL CHANCE OF A THUNDERSTORM LATE TONIGHT OR
SATURDAY...MAINLY IN SAN DIEGO COUNTY. OTHERWISE...OCCASIONAL BKN
CLOUDS AT/ABOVE 10000 FT MSL WILL OCCUR.

MTNS/DESERTS...ISOLATED TO SCATTERED THUNDERSTORMS WILL OCCUR THIS
AFTERNOON/EARLY THIS EVENING...MOST NUMEROUS IN SAN
BERNARDINO/RIVERSIDE COUNTIES. A THUNDERSTORM COULD REACH
KPSP...WITH GREATEST THREAT BEING LIGHTNING. LOCAL VIS OF 3 MI WILL
OCCUR WITH HEAVIER SHOWERS. BASES OF THE BKN-OVC CLOUDS WILL BE
AT/ABOVE 8000 FT WITH ISOLATED TOPS TO 35000 FT MSL. THERE IS A
CHANCE OF THUNDERSTORMS AGAIN SATURDAY.

&&

.MARINE...
100 PM PDT...ISOLATED SHOWERS WERE OCCURRING EARLY THIS AFTERNOON
OVER THE COASTAL WATERS...BUT THE THREAT OF LIGHTNING STRIKES WILL
BE MINIMAL THE REST OF THIS AFTERNOON. THERE IS A SMALL CHANCE OF A
THUNDERSTORM LATE TONIGHT OR EARLY SATURDAY. AFTER SATURDAY...NO
HAZARDOUS MARINE WEATHER THROUGH WEDNESDAY.

&&

.SKYWARN...
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...HEAT ADVISORY UNTIL 9 PM PDT THIS EVENING FOR THE COACHELLA
     VALLEY...SAN DIEGO COUNTY DESERTS.

PZ...NONE.

&&

$$

PUBLIC...JAD
AVIATION/MARINE...MAXWELL


















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