Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 311029
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
329 AM PDT THU JUL 31 2014

.SYNOPSIS...
SLIGHTLY WARMER WEATHER WILL DEVELOP TODAY BEFORE THUNDERSTORMS
RETURN TO THE FORECAST TO CLOSE THE WEEK. MONSOONAL MOISTURE WILL
BEGIN TO RETURN ON FRIDAY...AND CONTINUE THROUGH THE WEEKEND.
THIS...AND AN UPPER-LEVEL DISTURBANCE...WILL INCREASE THE CHANCE
OF SHOWERS AND THUNDERSTORMS ACROSS MOST OF THE REGION...MAINLY
SATURDAY AND SUNDAY. DRY WEATHER WILL DEVELOP MONDAY THROUGH MID
NEXT WEEK AS UPPER-LEVEL HIGH PRESSURE REBUILDS CLOSER TO THE
AREA. HIGHS THIS WEEKEND WILL BE SLIGHTLY COOLER...THEN SLIGHTLY
WARM NEXT WEEK WITH A MODERATE TO SHALLOW MARINE LAYER.

&&

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

AT 3 AM PDT...WATER VAPOR SATELLITE IMAGERY DISPLAYED AN UPPER-
LEVEL HIGH NEAR THE ARIZONA/NEW MEXICO/MEXICO BORDER. FOG
SATELLITE SHOWED PATCHY LOW CLOUDS ALONG PORTIONS OF THE COAST
STRETCHING TO 10 MILES INLAND...MAINLY IN SAN DIEGO COUNTY.

SLIGHTLY ABOVE NORMAL HIGH TEMPERATURES WILL OCCUR TODAY AS THE
AFOREMENTIONED UPPER-LEVEL HIGH REMAINS CLOSE BY. MOST AREAS WILL
HAVE HIGHS AROUND 5 DEGREES F ABOVE NORMAL. THE PATTERN WILL
BEGIN TO CHANGE ON FRIDAY AS THE UPPER-LEVEL HIGH SHIFTS TOWARDS
THE NORTHEAST. THIS WILL HELP SHIFT MID-LEVEL FLOW MORE FROM THE
SOUTHEAST...ADVECTING IN SOME MONSOONAL MOISTURE. CUMULUS CLOUDS
WILL RETURN IN THE AFTERNOON OVER MOUNTAIN PEAKS FRIDAY...WITH AN
ISOLATED THUNDERSTORM POSSIBLE. HIGHS WILL SHIFT CLOSER TO NORMAL.

SHOWER AND THUNDERSTORM ACTIVITY WILL INCREASE IN COVERAGE OVER
THE WEEKEND AS FORECAST PRECIPITABLE WATER VALUES RISE ABOVE 1.50
INCHES ACROSS MUCH OF THE AREA. 31/0000 UTC ECMWF/GFS/GEM ARE IN
FAIRLY GOOD AGREEMENT WITH MOVING A WEAK UPPER-LEVEL DISTURBANCE
OVER THE REGION THIS WEEKEND. THIS WILL CREATE SUFFICIENT
INSTABILITY TO GENERATE THUNDERSTORMS OVER THE
MOUNTAINS...DESERTS AND POSSIBLY THE FAR INLAND VALLEYS SATURDAY
AND SUNDAY. THE GREATEST COVERAGE OF STORMS WILL BE IN THE
AFTERNOONS DUE TO DIURNAL HEATING. HOWEVER...ELEVATED CONVECTION
COULD GENERATE SOME STORMS IN THE OVERNIGHT HOURS. ALL PREVIOUSLY
MENTIONED MODELS SHOW THE DISTURBANCE MOVING ACROSS THE REGION
THIS WEEKEND. HOWEVER...THEY DO DISAGREE SOMEWHAT WITH TIMING AND
LOCATION WHERE PRECIPITATION WILL FALL. FOR NOW...KEPT SLIGHT
CHANCE/CHANCE OF SHOWERS AND THUNDERSTORMS IN THE FORECAST FOR
THIS WEEKEND...AND ADDED A SLIGHT CHANCE FOR MOUNTAIN AND HIGH
DESERT LOCATIONS FOR LATE SUNDAY NIGHT. THE DISTURBANCE WILL ALSO
HELP HIGH TEMPERATURES TO DIP AROUND 5 TO 10 DEGREES BELOW NORMAL
BY SUNDAY AND MONDAY. THE MARINE LAYER WILL SLIGHTLY DEEPEN AND
BECOME LESS PATCHY IN THE OVERNIGHT AND MORNING HOURS.

BY MONDAY...THE UPPER-LEVEL HIGH SHIFTS SOUTH AGAIN...AND BUILDS
MORE OVER SW CA. THIS WILL SHIFT MID AND UPPER-LEVEL FLOW TO
SOUTHWESTERLY AGAIN AND HELP LOWER PRECIPITABLE WATER VALUES
CLOSER TO 1 INCH ACROSS THE REGION. HIGHS WILL WARM...BUT STILL
REMAIN MOSTLY AT OR JUST BELOW SEASONAL NORMALS. THE MAINE LAYER
WILL DEVELOP EACH NIGHT AND MORNING...PUSHING AROUND 15-20 MILES
INLAND EACH MORNING.

&&

.AVIATION...
310900Z...COASTS/VALLEYS...STRATUS WITH BASES 800-1000 FT MSL AND
TOPS 1200 FT MSL EXTENDING 10SM INLAND THROUGH 16Z AFFECTING KCRQ
AND KSAN. LOW CLOUDS RETREATING BACK TO THE COASTLINE BY 18Z.

TONIGHT...A SLIGHTLY DEEPER CLOUD LAYER WITH BASES FROM 900-1200
FEET TOPS 015 MOVING AFFECTED KSAN/KCRQ/KSNA AFT 07Z.

MOUNTAINS/DESERTS...SKC-SCT200 THIS MORNING. AFT 18Z...SCT080-100
WITH CUMULUS BUILDUPS.

&&

.MARINE...
200 AM 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...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC...JJT
AVIATION/MARINE...MOEDE







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