511  
FXUS66 KSGX 300412  
AFDSGX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN DIEGO CA  
912 PM PDT FRI JUL 29 2016  
   
SYNOPSIS
 
 
AN INCREASE IN MONSOONAL MOISTURE OVER THE NEXT FEW DAYS WILL  
LEAD TO A BETTER CHANCE OF AFTERNOON AND EARLY EVENING HEAVY  
SHOWERS AND THUNDERSTORMS OVER THE MOUNTAINS AND DESERTS THROUGH  
TUESDAY WHILE CONDITIONS REMAIN FAIR WEST OF THE MOUNTAINS.  
DURING THE MIDDLE TO LATTER PART OF NEXT WEEK, DRIER AIR IS  
FORECAST TO MOVE IN AS A WEST COAST TROUGH DEVELOPS. THIS WILL  
LEAD TO DECREASING CHANCES OF MOUNTAIN AND DESERT THUNDERSTORMS  
THEN. PATCHY NIGHT AND MORNING MARINE LAYER LOW CLOUDS AND FOG  
WILL CONTINUE TO BE POSSIBLE OVER THE COAST AND WESTERN VALLEYS.  
 

 
   
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
 
 
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO  
COUNTIES...  
 
A FEW THUNDERSTORMS DEVELOPED OVER THE MOUNTAINS TODAY, BUT THEY  
WERE KEPT IN CHECK WITH NO SIGNIFICANT IMPACTS. THE MAX RAINFALL  
RECORDED WAS 0.20 INCHES AT BALDWIN LAKE. 28 LIGHTNING STRIKES  
OCCURRED ACROSS THE MOUNTAINS AND HIGH DESERTS.  
 
VERY ACTIVE CONVECTION IS OCCURRING ACROSS ARIZONA INCLUDING THE  
GREATER PHOENIX METRO. THUNDERSTORM OUTFLOWS CONTINUE TO LEAD TO  
TSTORM DEVELOPMENT FURTHER AND FURTHER WEST. A LARGE CONVECTIVE  
COMPLEX IS ALSO GOING OVER MEXICO JUST SOUTH OF AZ. WE WILL HAVE  
TO SEE IF PERHAPS EVENTUALLY SOME OF THIS OUTFLOW OR AN MCV COMES  
FROM THIS ACTIVITY. HOWEVER, THE HIGH RES MODELS CONTINUE TO ONLY  
SHOW ISOLATED CONVECTION IN OUR MOUNTAINS AND DESERTS EACH OF THE  
NEXT FEW DAYS.  
 
MODELS SHOW MONSOONAL MOISTURE INCREASING FROM THE EAST TO  
SOUTHEAST DIRECTION THROUGH NEXT TUESDAY, WITH PRECIPITABLE WATER  
REACHING 1.4 INCHES SATURDAY, 1.7 INCHES SUNDAY AND MONDAY, AND  
1.8 INCHES TUESDAY. THIS MOISTURE, IN ADDITION TO INSTABILITY  
PRODUCED BY DAYTIME HEATING, WILL RESULT IN CHANCES FOR AFTERNOON  
AND EARLY EVENING HEAVY SHOWERS AND THUNDERSTORMS OVER THE  
MOUNTAINS AND DESERTS THROUGH AT LEAST TUESDAY. STORM MOTION LOOKS  
LIGHT ON SATURDAY AND SUNDAY, WHICH WOULD INCREASE THE FLASH FLOOD  
THREAT, ESPECIALLY ON SUNDAY WHEN MORE LOW LEVEL MOISTURE MOVES  
IN. THE STORM MOTION INCREASES SLIGHTLY FROM THE EAST ON MONDAY  
AND TUESDAY, WHICH COULD RESULT IN THUNDERSTORMS DEVELOPING OVER  
THE COASTAL SLOPES. HOWEVER, WITH A 700-300 MB WIND OF ONLY 10 KT,  
IT WILL LIKELY BE LIGHT ENOUGH TO CONTINUE TO THE HIGHER FLASH  
FLOODING THREAT.  
 
ALTHOUGH MOISTURE STARTS TO DECREASE WEDNESDAY INTO THURSDAY,  
WOULDN'T BE SURPRISED IF THERE WAS STILL ENOUGH MOISTURE AND  
INSTABILITY TO CREATE ISOLATED AFTERNOON/EARLY EVENING SHOWERS  
AND THUNDERSTORMS OVER THE MOUNTAINS ON THOSE DAYS. MEANWHILE,  
ONSHORE FLOW WILL CONTINUE TO RESULT IN PATCHY NIGHT AND MORNING  
STRATUS/FOG OVER THE COAST AND WESTERN VALLEYS.  
 

 
   
AVIATION
 
 
30400Z...COAST AND VALLEYS...PATCHY STRATUS WILL DEVELOP WITHIN 10-  
15 MILES OF THE COAST THROUGH 14Z SATURDAY, WITH GREATEST COVERAGE  
EXPECTED OVER SD COUNTY. CLOUD BASES WILL BE BETWEEN 800 AND 1400 FT  
MSL WITH TOPS AOB 1500 FT MSL. LOCAL VIS RESTRICTIONS OF 1-3 SM WILL  
OCCUR WHERE STRATUS INTERSECTS HIGHER COASTAL TERRAIN. CLEARING TO  
THE COAST IS EXPECTED BY 16Z SATURDAY WITH LIGHT SEA BREEZES  
SATURDAY AFTERNOON.  
 
MOUNTAINS AND DESERTS...SCATTERED THUNDERSTORMS WILL DEVELOP  
BETWEEN 18Z SATURDAY AND 02Z SUNDAY. STORMS MAY PRODUCE STRONG  
UDDFS AND LLWS, LIGHTNING AND SMALL HAIL. OTHERWISE, UNRESTRICTED VIS  
AND SKC-SCT AOA 10000 FT MSL WILL PREVAIL THROUGH SATURDAY.  
 

 
   
MARINE
 
 
NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH TUESDAY.  
 

 
   
FIRE WEATHER
 
 
WITH INCREASING MONSOONAL MOISTURE AND INSTABILITY, AFTERNOON  
AND EARLY EVENING THUNDERSTORMS ARE LIKELY TO DEVELOP OVER THE  
MOUNTAINS AND PORTIONS OF THE DESERTS THROUGH AT LEAST TUESDAY.  
THE THUNDERSTORMS MAY INITIALLY PRODUCE DRY LIGHTNING STRIKES  
TODAY AND SATURDAY, AND THEN BECOMING MAINLY WET STRIKES BY  
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...GREGORIA  
AVIATION/MARINE...BA  
 
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