Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 170935
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
230 AM PDT WED SEP 17 2014

.SYNOPSIS...
HOT AND HUMID WEATHER WILL CONTINUE TODAY. THE HUMID AIR WILL BRING
SOME INLAND THUNDERSTORMS. A LOW PRESSURE SYSTEM WILL MOVE INTO THE
REGION THURSDAY THROUGH THE WEEKEND WHICH WILL BRING A DRYING AND
COOLING TREND AND A RETURN OF THE MARINE LAYER AND COASTAL CLOUDS
NIGHTS AND MORNINGS. HIGHER PRESSURE WILL REDEVELOP NEXT
WEEK...BRINGING WARMER WEATHER.

&&

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

DESERT THUNDERSTORMS FROM LAST EVENING HAVE DIMINISHED AND ONLY A
FEW DEBRIS CLOUDS FROM THEM REMAIN OVER OUR REGION THIS MORNING. THE
MOISTURE COMING FROM FORMER HURRICANE ODILE WILL CONTINUE WITH US
ONE MORE DAY. PRECIPITABLE WATER AMOUNTS ARE UP TO TO 2 INCHES IN
THE DESERT AND CLOSER TO 1.5 INCHES NEAR THE COAST. INSTABILITY WITH
SURFACE DAYTIME HEATING TODAY WILL PRODUCE DEEP CONVECTION AND
THUNDERSTORMS. THE FLOW ALOFT...WHICH WAS EASTERLY YESTERDAY PUSHING
TSTORMS TO THE COAST...WILL TURN WESTERLY TODAY. THAT MEANS THE
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO STAY WELL INLAND. LIGHTER
WINDS THROUGH THE ATMOSPHERIC COLUMN WILL ALLOW THE CONVECTION TO
MAXIMIZE THE RAINFALL WITH STATIONARY TSTORMS. LOWER LEVELS WILL
BECOME MORE SATURATED TODAY...WHICH WILL HELP MITIGATE SEVERE TSTORM
WINDS AND DOWNDRAFTS...BUT IT WILL INCREASE THE THREAT OF FLASH
FLOODING. ACCORDINGLY...A FLASH FLOOD WATCH HAS BEEN ISSUED FOR THE
MOUNTAINS AND DESERTS TODAY. A LOW PRESSURE TROUGH WILL PUSH
SOUTHWARD ALONG THE WEST COAST TODAY AND THURSDAY...CUTTING OFF
FRIDAY AND SPINNING OVER SOUTHERN CALIFORNIA THIS WEEKEND. THIS WILL
PUSH THE MOISTURE ASIDE THIS EVENING AND GIVE US DRIER WEATHER FOR
SEVERAL DAYS. IT WILL ALSO BRING A COOLER AIR MASS TO REPLACE OUR
OPPRESSIVELY HOT AND HUMID ONE. AND IT WILL REDEVELOP A MARINE LAYER
WITH ITS COASTAL CLOUDS NIGHTS AND MORNINGS. THE MARINE LAYER WILL
BE AT ITS DEEPEST FRIDAY MORNING WITH SOME FOG WORKING INTO THE
INLAND VALLEYS. SOME MODEL GUIDANCE HINTS AT THIS CUTOFF LOW DRAWING
UP MOISTURE FROM THE SOUTH OVER THE WEEKEND THAT COULD LEAD TO A FEW
SHOWERS OR TSTORMS...BUT THE OVERALL MODEL CONSENSUS KEEPS US DRY.
THIS WILL BE WORTH WATCHING. NEXT WEEK THE CUTOFF LOW WILL LIFT OUT
TO THE EAST AND A HIGH PRESSURE RIDGE APPEARS READY TO DEVELOP OVER
THE WESTERN STATES. THE MODELS DIFFER ON HOW AND WHERE TO PLACE THE
RIDGE...BUT DRY AND WARMER WEATHER IS A GOOD FORECAST.

&&

.AVIATION...
170930Z...FEW CLOUDS AOA 10000 FT MSL WITH UNRESTRICTED VIS THROUGH
THE MORNING. BETWEEN 18Z WED AND 03Z THU...SHOWERS AND THUNDERSTORMS
DEVELOPING OVER THE MOUNTAINS...DESERTS...AND INLAND VALLEYS.
THUNDERSTORM BASES NEAR 6000 FT MSL WITH TOPS TO 35000 FT MSL.
KONT...KPSP AND KTRM MAY BE IMPACTED WITH REDUCED VIS IN HEAVY RAIN
AND GUSTY OUTFLOW WINDS.

&&

.MARINE...
230 AM...NO HAZARDOUS MARINE WEATHER EXPECTED THROUGH SUNDAY.

&&

.BEACHES...
AT 2 PM...A LONG PERIOD SOUTH-SOUTHWEST SWELL WILL CONTINUE TO
PRODUCE STRONG RIP AND LONGSHORE CURRENTS AS WELL AS ELEVATED SURF
THROUGH THURSDAY. SURF OF 4 TO 6 FEET WITH LOCALLY HIGHER SETS IS
EXPECTED ON EXPOSED SOUTHWEST FACING BEACHES. THE SWELL WILL SLOWLY
LOWER FRIDAY INTO THE WEEKEND...DIMINISHING THE SURF AND RIP CURRENT
THREAT. A BEACH HAZARDS STATEMENT REMAINS IN EFFECT THROUGH THURSDAY
EVENING.

&&

.SKYWARN...
SKYWARN ACTIVATION MAY BE REQUESTED TODAY.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...FLASH FLOOD WATCH FROM 10 AM PDT THIS MORNING THROUGH THIS
     EVENING FOR THE APPLE AND LUCERNE VALLEYS...COACHELLA
     VALLEY...RIVERSIDE COUNTY MOUNTAINS...SAN BERNARDINO COUNTY
     MOUNTAINS...SAN DIEGO COUNTY DESERTS...SAN DIEGO COUNTY
     MOUNTAINS.

     BEACH HAZARDS STATEMENT THROUGH THURSDAY EVENING FOR THE
     BEACHES IN THE ORANGE COUNTY COASTAL AREAS...SAN DIEGO COUNTY
     COASTAL AREAS.

PZ...NONE.

&&

$$

PUBLIC...MM
AVIATION/MARINE/BEACHES...SS





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