Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 202100
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
200 PM PDT WED AUG 20 2014

.SYNOPSIS...
UPPER LEVEL LOW WILL MOVE SLOWLY INLAND ACROSS SOUTHERN CALIFORNIA
THROUGH TOMORROW...WITH COOLER CONDITIONS AND UNSETTLED WEATHER
CONTINUING.  SCATTERED SHOWERS AND THUNDERSTORMS ACTIVITY WILL
DECREASE LATE TONIGHT...BUT INCREASE AGAIN DURING THE DAY ON
THURSDAY...MAINLY OVER THE MOUNTAINS AND DESERTS.  THUNDERSTORMS
WILL BE CAPABLE OF PRODUCING LARGE HAIL AND HEAVY RAIN...WITH
LOCALIZED FLASHING FLOODING POSSIBLE.  DRY AND WARMER WEATHER WILL
RETURN TO SOUTHERN CALIFORNIA FOR FRIDAY AND THE WEEKEND...LIKELY
CONTINUING INTO NEXT WEEK.

&&

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

WATER VAPOR IMAGERY CONTINUES TO SHOW AN IMPRESSIVE AND UNSEASONAL
UPPER LEVEL LOW SLOWLY MOVING SOUTHEASTWARD OVER THE BIGHT...WITH
THE CENTER CURRENTLY ALONG THE ORANGE COUNTY COAST.  THIS UPPER
LEVEL LOW CONTINUES TO PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS
OVER THE INLAND AREAS.  CURRENT RADAR IMAGERY SHOWS SEVERAL SHOWER
BANDS...BUT THE MOST ATTENTION WORTHY AT THIS TIME IS FORMING OVER
THE INLAND EMPIRE...WITH THUNDERSTORMS EXTENDING FROM LAKE ELSINORE
NORTHWARD INTO RIVERSIDE.  GIVEN THE TRENDS FROM THIS
MORNING...STILL THINK THAT SOME DECENT SIZE HAIL WILL BE POSSIBLE.
THE MODELS CONTINUE TO INDICATE 1.2 - 1.3 INCH PWS OVER THE
AREA...WHICH BACKS UP THE 12Z KNKX SOUNDING READING OF 1.21 INCHES
OVER THE AREA...SO THINK THAT SOME LOCALIZED FLASH FLOODING WILL BE
POSSIBLE...ESPECIALLY IF THUNDERSTORMS GETTING GOING IN THE MOUNTAIN
AND DESERT AREAS.  THEREFORE...WILL KEEP THE FLASH FLOOD WATCH IN
PLACE THROUGH 9 PM.  OTHERWISE...EXPECTING THE SHOWER AND
THUNDERSTORM THREAT TO DECREASE OVERNIGHT TONIGHT.  THAT BEING SAID
THOUGH...THERE IS STILL ENOUGH MIDLEVEL INSTABILITY AND DYNAMICS
WITH THIS UPPER LOW...THAT A SLIGHT CHANCE WILL REMAIN...ESPECIALLY
AS A GOOD PORTION OF OUR COUNTY WARNING AREA REMAIN UNDER THE BEST
DIFLUENT AREA ALOFT.

THE UPPER LEVEL LOW WILL BE OVER SAN DIEGO COUNTY LATE TONIGHT AND
DURING THE DAY ON THURSDAY...BEFORE SLOWLY SHIFTING INLAND THURSDAY
NIGHT.  FOR THIS REASON...BELIEVE THAT SHOWERS AND THUNDERSTORMS
WILL STILL BE POSSIBLE THROUGH TOMORROW...WITH THE MOUNTAINS AND
DESERTS HAVING THE BEST CHANCE AT SEEING SOME ACTIVITY.  DRIER AIR
SHOULD START TO FILTER INTO THE REGION ON THE BACK SIDE OF THIS LOW
THOUGH...SO EXPECT THE UNSETTLED WEATHER TO GRADUALLY DECREASE LATE
IN THE DAY.

WEAK RIDGING WILL THEN DEVELOP OVER THE REGION FOR FRIDAY AND THE
WEEKEND...BRINGING DRY AND WARMER CONDITIONS TO THE SOUTHLAND.  THIS
RIDGE WILL WEAKEN A BIT FOR EARLY NEXT WEEK...AS A TROUGH MOVES
THROUGH THE GREAT BASIN...BUT SHOULD REBOUND BY MID WEEK.
THEREFORE...EXPECT DRY CONDITIONS TO CONTINUE TO PREVAIL...WITH SOME
MINOR FLUCTUATIONS IN TEMPERATURES POSSIBLE FOR THE WORK WEEK.

&&

.AVIATION...
202015Z...STRATUS...WITH BASES AROUND 1900-2400 FT ABOVE MEAN SEA
LEVEL AND TOPS AROUND 3000 FT ABOVE MEAN SEA LEVEL...WILL MOVE BACK
INLAND 25 TO POSSIBLY 40 MILES INLAND DURING THE 21/0000-1400 UTC
TIME-FRAME...BUT MAY BE SOMEWHAT PATCHY IN PLACES. CONFIDENCE IN
FORECAST IS MODERATE. CLEARING IS LIKELY 21/1500-1800 UTC.

SCATTERED SHOWERS WITH ISOLATED EMBEDDED THUNDERSTORMS...WITH BASES
AROUND 4000-6000 FT ABOVE MEAN SEA LEVEL...AND CB TOPS 35000-40000
FT ABOVE MEAN SEA LEVEL...WILL CONTINUE ACROSS SAN DIEGO...RIVERSIDE
AND POSSIBLY INTO SAN BERNARDINO COUNTY THROUGH THE AFTERNOON.
LIGHTNING...SMALL HAIL...GUSTY WINDS AND LOCAL VISIBILITY AOB 1 MILE
WILL BE POSSIBLE NEAR STORMS. THUNDERSTORMS CHANCES WILL CONTINUE
THROUGH THURSDAY MORNING ACROSS THE REGION.

&&

.MARINE...
115 PM...ALTHOUGH THUNDERSTORM ACTIVITY HAS DIMINISHED THIS
AFTERNOON...THE UPPER LEVEL LOW WILL NOT MOVE INLAND UNTIL
TOMORROW...AND SO A SLIGHT CHANCE OF THUNDERSTORMS FOR THE COASTAL
WATERS CONTINUES THROUGH TOMORROW MORNING. CLOUD-TO-WATER
LIGHTNING...GUSTY WINDS...SMALL HAIL...ROUGH SEAS AND ISOLATED
WATERSPOUTS MAY ACCOMPANY THUNDERSTORMS. A MARINE WEATHER STATEMENT
REMAINS IN EFFECT.

&&

.BEACHES...
THE BEACH HAZARDS STATEMENT FOR LIGHTNING AT THE BEACHES WAS
CANCELLED...AS THUNDERSTORM ACTIVITY HAS DISSIPATED SINCE MORNING.
HOWEVER...THERE IS STILL A SLIGHT CHANCE OF THUNDERSTORMS THROUGH
TOMORROW MORNING.

ALSO...A 4-6 FOOT/12 SECOND PERIOD SOUTH SWELL FROM TROPICAL CYCLONE
ACTIVITY WILL BUILD TOMORROW THROUGH SATURDAY...AND CONTINUE EARLY
MONDAY...LIKELY BRINGING ELEVATED SURF AND STRONG RIP
CURRENTS...MAINLY TO ORANGE COUNTY BEACHES AND NORTHERN SAN DIEGO
COUNTY BEACHES.

&&

.SKWYARN...
SKYWARN IS ACTIVATED FOR SAN DIEGO AND RIVERSIDE COUNTIES.
ACTIVATION MAY BE NEEDED LATER TODAY FOR THE OTHER COUNTIES.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...FLASH FLOOD WATCH UNTIL 9 PM PDT THIS EVENING FOR THE BEACHES IN
     THE APPLE AND LUCERNE VALLEYS...COACHELLA VALLEY...
     RIVERSIDE COUNTY MOUNTAINS...SAN BERNARDINO COUNTY
     MOUNTAINS...SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE
     INLAND EMPIRE...SAN DIEGO COUNTY DESERTS...SAN DIEGO COUNTY
     MOUNTAINS...SAN DIEGO COUNTY VALLEYS...SANTA ANA MOUNTAINS
     AND FOOTHILLS.

PZ...NONE.

&&

$$

PUBLIC...PALMER
AVIATION/MARINE...HARRISON





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