Weather Service Report


920 
FXUS66 KSGX 022032
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
132 PM PDT THU JUL 2 2015

.SYNOPSIS... 
ISOLATED THUNDERSTORMS POSSIBLE TODAY ACROSS PORTIONS OF THE
MOUNTAINS AND DESERTS. DRIER FRIDAY WITH SMALLER PRECIPITATION
CHANCES ACROSS THE REGION. DRY ON INDEPENDENCE DAY...THEN SLIGHT
CHANCE OF THUNDERSTORMS SUNDAY AFTERNOON OVER PORTIONS OF THE
MOUNTAINS AND DESERTS WITH A SMALL INCREASE IN MONSOONAL MOISTURE.
WESTERLY FLOW ALOFT EARLY NEXT WEEK WILL CREATE DRY AND SEASONAL
WEATHER. NIGHT/MORNING LOW CLOUDS WILL DEVELOP OVER THE COAST AND
VALLEYS THROUGH THE PERIOD.
 
&&

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

THE 02/1200 UTC GFS AND ECMWF ARE IN RELATIVELY GOOD AGREEMENT
THROUGH THE LONG-TERM.

AT 1 PM PDT...WATER VAPOR SATELLITE IMAGERY DISPLAYED A BROAD
UPPER-LEVEL HIGH STRETCHING FROM NORTHERN CA TO WESTERN NEW
MEXICO...AND AN UPPER-LEVEL LOW AROUND 550 MILES SW OF SAN DIEGO.
VISIBLE SATELLITE SHOWED CUMULUS BUILD-UPS OVER THE
MOUNTAINS...AND LOW-LEVEL CLOUDS OVER PORTIONS OF THE COASTAL
WATERS. 

DIURNAL HEATING...COMBINED WITH A MOIST ATMOSPHERE...WILL
CONTINUE THE POSSIBILITY OF ISOLATED SHOWERS AND THUNDERSTORMS
OVER PORTIONS OF THE MOUNTAINS AND DESERTS THROUGH THIS AFTERNOON.
THE MAIN THREATS WITH STORMS WILL BE LIGHTNING...GUSTY WINDS...AND
ISOLATED FLASH FLOODING. NEGATIVE VORTICITY ADVECTION IS LIKELY
INHIBITING CONVECTION SO FAR THIS AFTERNOON. HOWEVER...AN ISOLATED
THUNDERSTORM OR TWO WILL STILL BE POSSIBLE...MAINLY OVER THE SAN
BERNARDINO COUNTY MTNS.

THE AFOREMENTIONED UPPER-LEVEL HIGH WILL SAG SOUTH
FRIDAY...TRANSITIONING MID AND UPPER-LEVEL FLOW FROM SOUTHEAST TO
MORE SOUTHERLY. THIS WILL HELP CUT OFF THE MONSOONAL MOISTURE OVER
THE AREA...AND LIMIT AFTERNOON THUNDERSTORM ACTIVITY ON FRIDAY TO
THE SAN BERNARDINO COUNTY MOUNTAIN PEAKS.

THE HIGH WILL TRANSITION FURTHER SOUTH OVER THE
WEEKEND...CONTINUING THE DEVELOPMENT OF NIGHT/MORNING LOW CLOUDS
OVER THE COAST AND VALLEYS AND DRY WEATHER ON SATURDAY. A SLIGHT
INTRUSION OF MONSOONAL MOISTURE TO THE MOUNTAINS AND DESERTS ON
SUNDAY WILL CREATE THE POSSIBILITY OF ISOLATED AFTERNOON
THUNDERSTORMS. THEN CONDITIONS WILL DRY OUT IN THE MID AND UPPER-
LEVELS AS THE CUT-OFF UPPER-LEVEL LOW MOVES CLOSER TO THE REGION
TO OUR NORTH...SHIFTS MID-LEVEL FLOW TO THE SOUTHWEST...AND
MAINTAINS ONSHORE FLOW WITH NEAR SEASONAL WEATHER AND HIGH
TEMPERATURES INTO EARLY NEXT WEEK.

&&

.AVIATION... 
022024Z...COAST/VALLEYS...THROUGH 03/0600 UTC...UNRESTRICTED VIS AND 
FEW-SCT CLOUDS AOA 10000 FT MSL. 03/0600-1500 UTC...STRATUS 
GRADUALLY DEVELOPING 10-20 SM INLAND...WITH BASES 700-1000 FT 
MSL...TOPS AROUND 1500 FT MSL AND AREAS OF VIS 3-5 SM. CHANCE THAT 
VIS COULD DROP TO 1-2 SM DURING THE 03/1300-1500 UTC TIME-PERIOD FOR 
THE COASTAL TAF SITES...BUT CONFIDENCE IS LOW. LOCAL VIS AOB 1 SM 
LIKELY FOR LOCATIONS 5-20 MILES INLAND...PARTICULARLY HIGHER 
TERRAIN. CONFIDENCE IN STRATUS OCCURRENCE IS MODERATE-TO-
HIGH...EXCEPT THERE IS LOW CONFIDENCE IN STRATUS/FOG MAKING IT INTO 
KONT. CLEARING OF STRATUS/FOG DURING THE 03/1500-1900 UTC TIME-
PERIOD.
 
MTNS/DESERTS...SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH 
03/0100 UTC...MAINLY OVER THE MTNS AND HIGH DESERTS. THUNDERSTORM 
BASES WILL BE NEAR 8000 FT MSL WITH CB TOPS TO 40000-45000 FT MSL. 
ANY STORMS THAT FORM MAY PRODUCE MOD-STG UP/DOWNDRAFTS...FREQUENT 
LIGHTNING...AND REDUCED VIS TO 3SM OR LESS IN RAIN. OTHERWISE...FEW-
SCT CLOUDS AOA 10000 FT MSL WITH UNRESTRICTED VIS PREVAILING THROUGH 
FRIDAY MORNING. 
 
&&

.MARINE... 
124 PM...NO HAZARDOUS WEATHER IS EXPECTED THROUGH TUESDAY. 

&&

.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...HARRISON

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