Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 011638
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
938 AM PDT WED JUL 1 2015

.SYNOPSIS...
FAVORABLE CONDITIONS WILL CONTINUE THE POSSIBILITY OF ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS OVER MOST AREAS TODAY. HEAVY
DOWNPOURS...GUSTY WINDS AND FREQUENT LIGHTNING STRIKES ARE EXPECTED
NEAR STORMS. OTHERWISE...HUMID CONDITIONS WILL CONTINUE WITH WARM
WEATHER TODAY. PRECIPITATION CHANCES WILL LOWER THURSDAY AND
FRIDAY AS DRIER AIR MOVES INTO THE REGION. DRY AND MORE SEASONAL
HIGH TEMPERATURES WILL END THE WEEK...WITH A SLOW RETURN OF
COASTAL/VALLEY NIGHT/MORNING LOW CLOUDS OVER THE WEEKEND AND EARLY
NEXT WEEK.

&&

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

AT 9 AM PDT...WATER VAPOR SATELLITE IMAGERY DISPLAYED AN UPPER-
LEVEL HIGH STRETCHING FROM CENTRAL NEVADA TO NW NEW MEXICO...AND
AN UPPER-LEVEL LOW AROUND 500 MILES SW OF SAN DIEGO. COMPOSITE
RADAR SHOWED SCATTERED SHOWERS AND THUNDERSTORMS MOVING NORTHWEST
ACROSS THE HIGH DESERT AND THE SAN BERNARDINO COUNTY
MOUNTAINS...AND A FEW ISOLATED SHOWERS OVER THE COAST. THE 01/1200
UTC KNKX SOUNDING CALCULATED A RECORD PRECIPITABLE WATER OF 1.79
INCHES...WHICH BREAKS THE OLD RECORD OF 1.58 INCHES.

MOIST MONSOONAL FLOW...DIURNAL HEATING AND A WEAK UPPER-LEVEL
DISTURBANCE MOVING ACROSS THE REGION WILL CONTINUE THE CHANCES OF
SHOWERS AND THUNDERSTORMS ACROSS MOST OF THE REGION TODAY. THE
BEST CHANCES FOR PRECIPITATION WILL BE OVER THE MOUNTAINS.
INCREASED MID AND UPPER-LEVEL CLOUD COVER COULD HELP LIMIT STORM
DEVELOPMENT FOR DIURNAL HEATING. HOWEVER...THE WEAK UPPER-LEVEL
WAVE FORECAST TO TRAVERSE THE REGION THIS AFTERNOON IS EXPECTED TO
CREATE ENOUGH INSTABILITY ALOFT FOR ISOLATED TO SCATTERED SHOWERS
AND THUNDERSTORMS ACROSS MOST AREAS AGAIN TODAY. THE MAIN THREATS
NEAR STRONG THUNDERSTORMS WILL BE GUSTY WINDS AND LIGHTNING. THE
HIGH PRECIPITABLE WATER WILL HELP GENERATE HEAVY DOWNPOURS AT
TIMES. ALTHOUGH...FAST STORM SPEED WILL LIMIT WIDESPREAD FLASH
FLOODING. THE GREATEST COVERAGE OF STORMS WILL BE LATE THIS
MORNING THROUGH THIS AFTERNOON. ANOTHER WEAK WAVE WILL CREATE A
SLIGHT POSSIBILITY OF SHOWERS/THUNDERSTORMS OVER THE REGION
TONIGHT.

THE UPPER-LEVEL HIGH WILL BEGIN TO SHIFT SOUTH ON THURSDAY AND
SWITCH MID-LEVEL FLOW FROM SE TO MORE SOUTHERLY. THIS WILL START
TO DRY THE ATMOSPHERE OVER SW CA...AND MAINLY LIMIT SLIGHT CHANCE
OF AFTERNOON THUNDERSTORMS TO THE MOUNTAINS AND HIGH DESERTS
THURSDAY AND FRIDAY. THE UPPER-LEVEL HIGH WILL EVENTUALLY SAG
SOUTH OVER THE WEEKEND INTO EARLY NEXT WEEK. THIS WILL SHIFT FLOW
ALOFT TO WEST/SOUTHWEST...CREATING SEASONAL DRY WEATHER WITH NEAR
NORMAL HIGHS AND NIGHT/MORNING LOW CLOUDS OVER THE COAST AND
VALLEYS.

&&

.AVIATION...
011600Z...OVC-BKN CLOUD DECKS WITHIN THE 10000-30000 FT MSL LAYER
AND SCATTERED-TO-NUMEROUS SHOWERS WITH ISOLATED THUNDERSTORMS WILL
CONTINUE ACROSS THE AREA THROUGH 2000 UTC...WITH THE PEAK ACTIVITY
OCCURRING 1600-1900 UTC. THUNDERSTORMS/SHOWERS PRIMARILY OCCURRING
OVER THE MTNS AND VALLEYS DURING THE 2000-02/0000 UTC TIME-
PERIOD...WITH A CHANCE FOR SOME STORMS MAKING IT INTO THE COASTAL
AREAS...WHILE THE DESERTS EXPERIENCE PRIMARILY DRY CONDITIONS AND
UNRESTRICTED VIS. THUNDERSTORM CB TOPS TO 30000 FT MSL.
THUNDERSTORMS COULD PRODUCE LOCALLY HEAVY RAIN AND STRONG DOWNDRAFT
WINDS. LOCAL VIS AOB 5SM POSSIBLE UNDER HEAVY RAIN.
THUNDERSTORMS/SHOWERS DIMINISHING FROM EAST TO WEST CHANCE THAT
PATCHY STRATUS/FOG...WITH BASES 400-800 FT MSL AND TOPS AROUND 1000
FT MSL...COULD FORM DURING THE 02/0900-1400 UTC TIME-PERIOD...BUT
CONFIDENCE IS LOW ON OCCURRENCE. CLOUDS BECOMING BKN-SCT IN THE
10000-30000 FT MSL LAYER FROM EAST TO WEST DURING THAT TIME-PERIOD.

WEST WINDS 15-25 KT WITH GUSTS 30-35 KT OVER MTN
RIDGES...THROUGH/BELOW CANYONS/PASSES AND INTO ADJACENT DESERT AREAS
WILL PRODUCE MOD-STG UDDFS/LLWS OVER AND EAST OF THE MTNS AFTER
02/0000 UTC.

&&

.MARINE...
900 AM...SLIGHT CHANCE FOR SHOWERS AND THUNDERSTORMS OVER THE
COASTAL WATERS TODAY AS AN UPPER LEVEL DISTURBANCE MOVES OVER THE
REGION FROM THE EAST. OTHERWISE...NO HAZARDOUS WEATHER IS EXPECTED
THROUGH SUNDAY.

&&

.BEACHES...
900 AM...THERE IS A CHANCE THAT SOME THUNDERSTORMS COULD DEVELOP AND
MOVE OVER THE BEACHES FROM TIME TO TIME TODAY...MAINLY DURING THE
AFTERNOON HOURS. THUNDERSTORMS CAN PRODUCE DANGEROUS LIGHTNING
STRIKES AT THE BEACHES.

&&

.SKYWARN...
SKYWARN ACTIVATION IS REQUESTED FOR ALL AREAS FOR TODAY. SPOTTERS
ARE REQUESTED TO SEND ANY REPORTS OF SEVERE WEATHER TO THE
NATIONAL WEATHER SERVICE OR VIA COUNTY SKYWARN NETS.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...

CA...NONE.
PZ...NONE.

&&

$$

PUBLIC...JJT
AVIATION/MARINE/BEACHES...HARRISON



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