Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 280430
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
930 PM PDT THU AUG 27 2015

.SYNOPSIS... HOT AGAIN FRIDAY WITH STRONG HIGH PRESSURE OVER THE
SOUTHWEST. THE HIGH WILL BREAK DOWN OVER THE WEEKEND WHICH WILL
RESULT IN COOLER WEATHER WEST OF THE MOUNTAINS SATURDAY. COOLING
WILL REACH THE DESERTS ON SUNDAY. THIS COOLER WEATHER PATTERN WILL
CONTINUE NEXT WEEK AS A TROUGH OF LOW PRESSURE DEEPENS ALONG THE
WEST COAST.

&&

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

THURSDAY WAS A HOT DAY WITH COASTAL HIGHS IN THE 80S TO AROUND
90...VALLEY HIGHS FROM 95-103...MOUNTAIN HIGHS FROM 80-95 AND DESERT
HIGHS FROM 105-112. NEWPORT BEACH HAD A HIGH OF 84 WHICH TIED THE
OLD RECORD OF 84 SET IN 1949.

FRIDAY WILL BE ANOTHER HOT DAY...NEARLY A REPEAT PERFORMANCE OF
TODAY THANKS TO A 593DM HIGH ANCHORED OVER ARIZONA. MAX TEMPS WILL
FLIRT WITH THE LOWER END OF HEAT ADVISORY THRESHOLDS...BUT A HEAT
ADVISORY IS NOT LIKELY TO BE ISSUED FOR A ONE DAY EVENT. THE MAIN
DIFFERENCE IN THE WEATHER TOMORROW WILL BE THE LACK OF THUNDERSTORMS
OVER THE MOUNTAINS. THE LOW LEVEL MONSOONAL MOISTURE THAT RESULTED
IN AFTERNOON CONVECTION THURSDAY WILL BE FORCED EASTWARD OUT OF OUR
AREA FRIDAY...REPLACED BY DRY SOUTHWEST FLOW ALOFT AHEAD OF A TROUGH
OVER THE EASTERN PACIFIC.

NEXT WEEK AN UNUSUAL LATE SUMMER UPPER AIR PATTERN BECOMES
ESTABLISHED OVER THE CONUS. A LONG WAVE TROUGH SETS UP OVER THE WEST
WHICH AMPLIFIES A MASSIVE UPPER RIDGE OVER THE EAST. THIS PATTERN
WILL BRING COOLER THAN AVERAGE WEATHER TO THE WEST AND MUCH WARMER
THAN AVERAGE WEATHER TO THE EAST.

IN SOUTHERN CALIFORNIA THE 500 MB HEIGHTS LOWER FROM 588 DM SUNDAY
TO 582 DM FRIDAY. BY MIDWEEK THE MAX TEMPERATURES WILL BE BELOW
AVERAGE IN MOST AREAS. IN ADDITION TO THE COOLING...THIS TROUGH
PATTERN WILL RESULT IN A MUCH DEEPER MARINE LAYER WEST OF THE MTNS
AND PRODUCE GUSTY WESTERLY WINDS IN THE MOUNTAINS AND DESERTS.

&&

.AVIATION...
280300Z... COAST/VALLEYS...THE 00Z NKX SOUNDING SHOWED AN ELEVATED
WEAK INVERSION OF 2 DEGREES C BETWEEN 1500 AND 3500 FEET. HI RES
MODEL GUIDANCE HAS BACKED OFF ON LOW CLOUD DEVELOPMENT TONIGHT ALONG
THE COAST SO CONFIDENCE IS LOWER FOR THE FORMATION OF BKN CIGS AT
THE COASTAL TAF SITES. HOWEVER...FEW-SCT THIN LOW CLOUDS BASED
AROUND 800-1200 FT MSL ARE LIKELY FOR COASTAL AREAS AFTER AROUND
28/11Z TONIGHT. VIS 3-5 SM...LOCALLY LOWER...IN FOG/HZ POSSIBLE
WHERE CLOUDS APPROACH HIGHER TERRAIN.

MOUNTAINS/DESERTS...MOSTLY CLEAR WITH UNRESTRICTED VIS THROUGH
FRIDAY NIGHT.

&&

.MARINE...

800 PM...NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH MONDAY.

&&

.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...MOEDE
AVIATION/MARINE...TS


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