948  
FXUS62 KCAE 071041  
AFDCAE  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE COLUMBIA SC  
641 AM EDT TUE JUL 7 2020  
   
SYNOPSIS
 
 
MOISTURE CONTINUES TO STREAM INTO THE REGION FROM THE SOUTH  
AHEAD OF AN AREA OF LOW PRESSURE MOVING EASTWARD THROUGH  
SOUTHERN GEORGIA. THIS WILL BRING INCREASING CHANCES OF SHOWERS  
AND THUNDERSTORMS INTO THE MIDDLE OF THE WEEK WITH HEAVY RAIN  
POSSIBLE. SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE FROM  
LATE THIS WEEK THROUGH THE WEEKEND AS A MOIST AIR MASS REMAINS  
OVER THE REGION.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
MID-LEVEL TROUGH WILL EXTEND OVER THE REGION TODAY AND BECOME  
CENTERED OVER THE REGION TONIGHT. AT THE SURFACE, A FRONTAL  
BOUNDARY WILL BE STALLED ACROSS THE AREA. SURFACE LOW PRESSURE  
WILL MOVE INTO THE AREA FROM THE SOUTHWEST THIS MORNING AND SET  
UP OVER THE CSRA BY TONIGHT. DEEP MOISTURE WILL BE IN PLACE WITH  
PRECIPITABLE WATER VALUES AROUND 2.4 INCHES WITH THE HIGHEST  
VALUES EAST. INSTABILITY APPEARS LIMITED WITH LI VALUES PEAKING  
AROUND -1 OR -2. WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS  
ARE EXPECTED DURING THE AFTERNOON WITH NUMEROUS SHOWERS  
CONTINUING INTO TONIGHT. THE MAIN THREAT IS LOCALLY HEAVY  
RAINFALL AND POTENTIAL FOR FLASH FLOODING. THE FORECAST AREA IS  
OUTLOOKED IN A MARGINAL RISK FOR EXCESSIVE RAINFALL BY WPC. THE  
AREAS THAT RECEIVED THE HEAVIEST RAINFALL ON MONDAY WILL BE  
PARTICULARLY SUSCEPTIBLE INCLUDING AIKEN AND EDGEFIELD COUNTIES  
AND EASTERN SUMTER, LEE, CLARENDON, AND SOUTHERN CHESTERFIELD  
COUNTIES. FLOODING IS NOT EXPECTED TO BE WIDESPREAD ENOUGH TO  
WARRANT A FLASH FLOOD WATCH. CLOUDS AND RAIN WILL KEEP  
TEMPERATURES AROUND 10 DEGREES BELOW NORMAL, WITH HIGHS ONLY IN  
THE LOWER TO MIDDLE 80S. OVERNIGHT LOWS IN THE LOWER 70S.  
 

 
   
SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/
 
 
THE UPPER LOW OVER THE REGION WEDNESDAY WILL MOVE OFF THE COAST  
WEDNESDAY NIGHT. THE SURFACE LOW WILL LINGER OVER THE COASTAL PLAIN.  
ALTHOUGH PWAT VALUES WILL REMAIN AT OR ABOVE 2 INCHES OVER MUCH OF  
THE AREA, THE DEEPEST MOISTURE WILL SHIFT TO THE COASTAL PLAIN.  
SHOWERS AND THUNDERSTORMS WILL BECOME MORE DIURNAL GIVEN LACK OF  
FORCING. INSTABILITY WILL LIKELY BE SLIGHTLY GREATER WITH SOME DRY  
AIR MOVING IN ALOFT AND STEEPER LOW LEVEL LAPSE RATES WHICH MAY BE  
SUFFICIENT TO POSE A THREAT FOR ISOLATED STRONG DOWNBURSTS. WE KEPT  
CATEGORICAL POPS FOR WEDNESDAY AFTERNOON AND CHANCE POPS INTO  
WEDNESDAY NIGHT. HIGH TEMPERATURES WILL REMAIN BELOW NORMAL IN THE  
MID 80S WITH OVERNIGHT LOWS IN THE LOW 70S.  
 

 
   
LONG TERM /THURSDAY THROUGH MONDAY/
 
 
A NEGATIVELY TILTED UPPER TROUGH SLOWLY MOVE EAST, THOUGH UPPER  
TROFINESS LINGERS OVER THE EASTERN CONUS. A POTENTIAL TROPICAL LOW  
WILL KEEP A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE AREA AS IT  
DRIFTS ALONG THE COAST THURSDAY NIGHT INTO FRIDAY. THE NHC CONTINUES  
TO GIVE THIS AREA OF LOW PRESSURE A 40 PERCENT CHANCE OF DEVELOPMENT  
AS IT MOVES INTO THE WARMER CAROLINA COASTAL WATERS BUT AT THAT  
POINT, WITH OUR AREA BEING ON THE WEST SIDE OF THE SYSTEM, IT WOULD  
POSE LITTLE THREAT. MOISTURE WILL LIKELY STAY IN THE AREA INTO EARLY  
NEXT WEEK AND WITH TEMPERATURES CLIMBING BACK TO NEAR NORMAL WITH  
MAINLY DIURNAL SHOWERS AND THUNDERSTORMS.  
 

 
   
AVIATION /12Z TUESDAY THROUGH SATURDAY/
 
 
A SURFACE LOW IS SLOWLY TRACKING EASTWARD THROUGH SOUTHERN GA  
TOWARDS SOUTHERN SC, CONTINUING TO BRING SHOWERS AND  
THUNDERSTORMS TO OUR REGION INTO EARLY WEDNESDAY. SCATTERED  
SHOWERS CURRENTLY REMAIN IN OUR AREA, WITH MORE MOVING IN FROM  
THE SOUTH AS THE EARLY MORNING PROGRESSES. MVFR/IFR CONDITIONS  
EXPECTED AS VISIBILITIES ARE FORECAST TO GO DOWN TO 4-5SM BY  
EARLY MORNING. VISIBILITIES WILL REMAIN LOW INTO THE AFTERNOON.  
WINDS GENERALLY CALM UNTIL DAYBREAK, BECOMING EASTERLY AT 5-10  
KNOTS. IN ADDITION TO SHOWERS, ISOLATED THUNDERSTORMS ARE  
EXPECTED TO DEVELOP IN THE AFTERNOON. EXPECT HIGHER RESTRICTIONS  
WITHIN THESE POCKETS OF INSTABILITY.  
   
EXTENDED AVIATION OUTLOOK
 
THE CHANCE FOR RESTRICTIONS FROM  
MAINLY DIURNAL CONVECTION AND EARLY MORNING FOG WILL PERSIST THROUGH  
THE WEEKEND.  
 

 
   
CAE WATCHES/WARNINGS/ADVISORIES
 
 
GA...NONE.  
SC...NONE.  
 

 
 

 
 
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