573  
FXUS62 KCHS 142348  
AFDCHS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHARLESTON SC  
748 PM EDT FRI AUG 14 2020  
   
SYNOPSIS
 
 
A TROUGH OF LOW PRESSURE WILL PERSIST INLAND, WHILE HIGH  
PRESSURE REMAINS OVER THE ATLANTIC THROUGH SATURDAY. A WEAK  
COLD FRONT WILL THEN PASS THROUGH THE AREA SUNDAY INTO SUNDAY  
NIGHT. A TROUGH WILL REDEVELOP OVER THE REGION DURING THE  
MIDDLE OF NEXT WEEK.  
 

 
   
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/
 
 
A CLUSTER OF SEVERE THUNDERSTORMS DEVELOPED ACROSS FAR SOUTHERN  
SC EARLIER THIS EVENING DUE TO THE COLLISION OF TWO OUTFLOW  
BOUNDARIES AND THE SEA BREEZE. THIS ACTIVITY THEN MOVED NORTH  
NORTHEAST AND HAS BEEN ON A STEADY WEAKENING TREND. ELSEWHERE,  
LITTLE TO NO PRECIPITATION IS OCCURRING AND UPSTREAM ACTIVITY IS  
WANING AS THE BOUNDARY LAYER STABILIZES FOLLOWING PEAK  
DIABATIC HEATING. ONCE THE MAIN CONVECTIVE CLUSTER PUSHES OUT OF  
THE FORECAST AREA INTO THE EASTERN SC MIDLANDS BY 830 PM, ONLY  
ISOLATED SHOWERS AND PERHAPS A T-STORM WILL BE POSSIBLE FOR THE  
REST OF THE NIGHT.  
 

 
   
SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/
 
 
THE UPPER TROUGH THAT HAS LINGERED JUST WEST OF THE AREA FOR  
SEVERAL DAYS WILL BEGIN TO PUSH EAST ON SATURDAY, MOVING  
OFFSHORE BY SUNDAY NIGHT. THIS WILL PUSH A WEAK COLD FRONT  
THROUGH THE AREA SUNDAY AND SUNDAY NIGHT. PLENTY OF MOISTURE  
WILL REMAIN IN PLACE THROUGH THE WEEKEND WHICH, COMBINED WITH A  
SERIES OF EMBEDDED SHORTWAVES, WILL PRODUCE NUMEROUS SHOWERS  
AND THUNDERSTORMS. PWATS WILL DROP PRECIPITOUSLY BY MONDAY  
BEHIND THE FRONT WITH VALUES BELOW 1.5" IN MOST LOCATIONS. A  
WEAK LEE TROUGH WILL EXIST ON MONDAY AND A SEA BREEZE WILL  
DEVELOP IN THE AFTERNOON, SO SCATTERED SHOWERS AND TSTMS ARE  
STILL EXPECTED ALBEIT WITH LOWER COVERAGE THAN OVER THE WEEKEND.  
 

 
   
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
 
 
A RETURN TO MORE UNSETTLED WEATHER IS EXPECTED DURING THE LONG TERM  
PERIOD. THE FORECAST AREA WILL BECOME POSITIONED BETWEEN A MID LEVEL  
TROUGH TO THE WEST AND RIDGING TO THE EAST. THIS SET-UP WILL BRING  
DEEP MOISTURE AND A SERIES OF SHORTWAVES BACK INTO THE AREA.  
MEANWHILE, ANOTHER SURFACE TROUGH WILL TAKE SHAPE OVER THE REGION BY  
THE MIDDLE OF THE WEEK. HIGHER THAN NORMAL RAIN CHANCES ARE  
EXPECTED, ESPECIALLY WEDNESDAY AND THURSDAY. TEMPERATURES WILL BE  
NEAR CLIMATOLOGY.  
 

 
   
AVIATION /00Z SATURDAY THROUGH WEDNESDAY/
 
 
ONGOING CONVECTION SHOULD MISS KCHS TO THE NORTH THIS EVENING.  
OVERNIGHT, THOUGH WE CANNOT RULE OUT A BRIEF SHOWER, POTENTIAL  
IS TOO LOW TO INCLUDE MENTION OF CONVECTION AT EITHER TERMINAL.  
ON SATURDAY, ANOTHER ROUND OF CONVECTION IS EXPECTED, THOUGH IT  
COULD BE QUITE LATE IN THE DAY TO REACH KCHS SO WE HELD OFF ON  
ANY MENTION THERE. GIVEN THE EARLIER CONVECTIVE INITIATION  
ACROSS SOUTHEAST GA DURING THE LAST SEVERAL DAYS, WE ADDED A  
VICINITY THUNDERSTORM AT KSAV AFTER 18Z.  
 
EXTENDED AVIATION OUTLOOK: FLIGHT RESTRICTIONS POSSIBLE IN  
SHOWERS AND THUNDERSTORMS EACH DAY, MAINLY IN THE AFTERNOON AND  
EVENING.  
 

 
   
MARINE
 
 
TONIGHT: ELEVATED SOUTH/SOUTHWEST WINDS OVERNIGHT DUE TO AN  
ENHANCED PRESSURE GRADIENT BETWEEN OFFSHORE HIGH PRESSURE AND  
INLAND LOW PRESSURE. WINDS COULD GUST NEAR 20 KT AT TIMES WITH  
SEAS AS UP TO 4 FEET EVEN OUTSIDE ANY STORMS.  
 
SATURDAY THROUGH WEDNESDAY: THE SOUTHWEST GRADIENT WILL BE  
SLIGHTLY ENHANCED THROUGH THE WEEKEND AS A COLD FRONT APPROACHES  
FROM THE WEST AND ATLANTIC HIGH PRESSURE PERSISTS OFFSHORE. A  
RELATIVELY WEAK PRESSURE PATTERN WILL THEN EXIST EARLY NEXT WEEK  
BEHIND THE FRONT. THE PRIMARY MARINE CONCERN WILL CONTINUE TO  
BE THE SCATTERED SHOWERS AND THUNDERSTORMS.  
 

 
   
CHS WATCHES/WARNINGS/ADVISORIES
 
 
GA...NONE.  
SC...NONE.  
MARINE...NONE.  
 

 
 

 
NEAR TERM...JRL  
SHORT TERM...JRL  
LONG TERM...ETM  
AVIATION...JRL  
MARINE...JRL/RJB  
 
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