269  
FXUS62 KCHS 182357  
AFDCHS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHARLESTON SC  
757 PM EDT WED JUL 18 2018  
   
SYNOPSIS
 
 
A COLD FRONT WILL APPROACH THE REGION FROM THE NORTH TONIGHT  
AND WILL STALL OVER OR CLOSE OUR AREA THURSDAY AND THURSDAY  
NIGHT. THE FRONT WILL THEN SLOWLY LIFT NORTH AS A WARM FRONT  
FRIDAY. A TROUGH OF LOW PRESSURE WILL THEN PERSIST INTO THE  
MIDDLE OF NEXT WEEK.  
 

 
   
NEAR TERM /UNTIL 6 AM THURSDAY MORNING/
 
 
LATEST RADAR TRENDS INDICATE NUMEROUS SHOWERS/THUNDERSTORMS OVER  
PARTS OF SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA LATE  
THIS EVENING WITH THE BULK OF THUNDERSTORM ACTIVITY OVER THE  
TRI-COUNTY REGION IN SOUTH CAROLINA AND NEAR THE I-16 CORRIDOR  
IN SOUTHEAST GEORGIA. SOME STRONGER THUNDERSTORMS COULD PRODUCE  
BOUTS OF GUSTY WINDS, FREQUENT LIGHTNING AND HEAVY RAINFALL OVER  
THE NEXT COUPLE HOURS WITHIN DEEP-LAYERED MOISTURE CHARACTERIZED  
BY PWATS AROUND 2.0 INCHES AND WEAK WIND SHEAR. A MARGINAL RISK  
OF SEVERE WEATHER REMAINS OVER MUCH OF THE AREA, WITH THE MAIN  
THREAT BEING DAMAGING WIND GUSTS FROM STRONG/SEVERE THUNDERSTORMS.  
THE BEST CASE FOR A STRONG AND/OR BRIEFLY SEVERE THUNDERSTORM  
WOULD BE IN PARTS OF SOUTHEAST GEORGIA WHERE SBCAPE REMAINS  
AROUND 3000 J/KG AND DCAPE REMAINS BETWEEN 800-1000 J/KG FOR THE  
NEXT COUPLE HOURS. HOWEVER, THE OVERALL TREND OF SEVERE  
POTENTIAL SHOULD LOWER WITH SUNSET. EARLY TONIGHT, THE BULK OF  
PRECIP ACTIVITY SHOULD WANE OVER THE AREA WITH SEVERAL AREAS  
LIKELY BECOMING DRY BY MIDNIGHT. GUIDANCE SUGGESTS AT LEAST A  
FEW SHOWERS AND/OR THUNDERSTORMS BEING POSSIBLE AS A WEAK COLD  
FRONT SLOWLY ENTERS INTO THE REGION FROM THE NORTH LATE, THEN  
STALLS OVER THE AREA AROUND DAYBREAK.  
 
LOW TEMPS WILL BE WARM AGAIN TONIGHT, ESPECIALLY WITHIN A LIGHT  
SOUTHERLY FLOW SOUTH OF THE APPROACHING FRONT. IN GENERAL, TEMPS  
SHOULD ONLY DIP INTO THE LOW/MID 70S INLAND TO UPPER 70S NEAR THE  
COAST. LATE TONIGHT, PATCHY SHALLOW FOG WILL BE POSSIBLE FOR  
LOCATIONS THAT RECEIVED RAIN. HOWEVER, PROBABILITIES/COVERAGE ARE  
TOO LOW TO MENTION IN THE FORECAST AT THIS TIME.  
 

 
   
SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/
 
 
THURSDAY THROUGH FRIDAY: A COLD FRONT WILL STALL OVER OR CLOSE TO  
THE REGION, AND A DEEP-LAYERED TROUGH WILL RESIDE OVER THE REGION.  
POOLING OF RICH MOISTURE FEATURING PWATS WELL OVER 2 INCHES WILL  
TRANSLATE TO AN ACTIVE PERIOD WITH NUMEROUS/WIDESPREAD SHOWERS/  
THUNDERSTORMS. MAXIMUM POPS ARE CAPPED AT LIKELY, WITH GREATEST  
COVERAGE FROM LATE MORNING INTO EARLY EVENING BOTH DAYS. HOWEVER,  
LOCALLY GREATER POPS WILL EVENTUALLY BE REQUIRED, ESPECIALLY WITHIN  
NEAR TERM FORECAST UPDATES. ALSO, CONVECTION COULD PERSIST THROUGH  
THURSDAY NIGHT WITHOUT THE USUAL SIGNIFICANT/DIURNAL DECREASE IN  
COVERAGE. THE PRIMARY CONCERN FOCUSES ON THE POTENTIAL FOR LOCALLY  
EXCESSIVE RAINFALL. THE THREAT FOR SEVERE WEATHER/LOCALLY DAMAGING  
WIND GUSTS SHOULD REMAIN LOW. CLOUDS/PRECIPITATION SHOULD HOLD  
MAX TEMPERATURES IN THE 80S, BELOW NORMAL FOR MID-JULY.  
 
SATURDAY: MODELS AGREE THAT SOMEWHAT DRIER AIR WILL WRAP AROUND THE  
DEEP LONGWAVE UPPER TROUGH OVER THE EASTERN CONUS AND INTO OUR  
REGION. THIS SHOULD RESULT IN SOMEWHAT REDUCED COVERAGE OF DIURNAL  
CONVECTION AS COMPARED WITH THURSDAY/FRIDAY, AND TEMPERATURES SHOULD  
RESPOND BY RECOVERING INTO THE MORE TYPICAL LOWER 90S AWAY FROM THE  
COAST. WARMER TEMPERATURES COULD PRODUCE STRONGER INSTABILITY AS  
COMPARED WITH THE NEXT COUPLE OF DAYS, PERHAPS RAISING THE THREAT  
FOR A FEW PULSE SEVERE THUNDERSTORMS WITH BRIEF/ISOLATED DAMAGING  
WIND GUSTS.  
 

 
   
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
 
 
THE MODELS ARE IN GOOD AGREEMENT SHOWING A STRONG TROUGH OVER THE  
EAST COAST SATURDAY NIGHT THROUGH MONDAY, WITH IT WEAKENING ON  
TUESDAY. HOWEVER, THEY DON'T AGREE AS MUCH WITH THE SURFACE PATTERN.  
THE MODELS HINT AT A TROUGH INLAND SATURDAY NIGHT INTO SUNDAY.  
ANOTHER COLD FRONT WILL SLOWLY APPROACH FROM THE NORTHWEST SUNDAY  
INTO MONDAY. THEN, THEY DISAGREE OVER WHETHER THE FRONT MAKES IT TO  
OUR AREA OR STAYS TO THE NORTH. REGARDLESS, THE END RESULT WILL BE A  
RAINY WEATHER PATTERN.  
 

 
   
AVIATION /00Z THURSDAY THROUGH MONDAY/
 
 
SHOWERS AND THUNDERSTORMS WILL LIKELY IMPACT BOTH CHS AND SAV  
TERMINALS FOR THE NEXT HOUR OR TWO, PRODUCING FLIGHT RESTRICTIONS  
BETWEEN 00-02Z THURSDAY. PRECIP ACTIVITY WILL THEN LIKELY DECREASE  
WITH BOTH TERMINALS EXPERIENCING VFR CONDITIONS FOR MUCH OF  
TONIGHT. HOWEVER, A FEW ADDITIONAL SHOWERS AND THUNDERSTORMS CAN  
NOT BE RULED OUT APPROACHING DAYBREAK THURSDAY AS A COLD FRONT  
APPROACHES FROM THE NORTH LATE TONIGHT. GREATER CHANCES OF  
SHOWERS/THUNDERSTORMS SHOULD OCCUR THURSDAY AFTERNOON/EVENING  
AS THE FRONT STALLS OVER THE REGION. VCTS HAS BEEN INCLUDED TO  
ACCOUNT FOR AFTERNOON/EVENING THUNDERSTORMS BEGINNING AROUND  
16Z AT THE SAV TERMINAL, THEN 19Z AT THE CHS TERMINAL.  
 
EXTENDED AVIATION OUTLOOK: MOST OF THE TIME VFR CONDITIONS WILL  
PREVAIL. HOWEVER, EPISODES OF FLIGHT RESTRICTIONS ARE LIKELY IN  
CONVECTION, AND LOW CEILINGS COULD OCCUR EVEN OUTSIDE ANY  
SHOWERS/THUNDERSTORMS DURING THE LATE NIGHT/EARLY MORNING HOURS.  
 

 
   
MARINE
 
 
THIS EVENING AND TONIGHT: SHOWERS AND/OR THUNDERSTORMS WILL CONTINUE  
TO DRIFT OVER COASTAL WATERS THIS EVENING, BEFORE GRADUALLY  
DECREASING IN COVERAGE EARLY TONIGHT. HOWEVER, ADDITIONAL SHOWERS  
AND THUNDERSTORMS COULD DEVELOP OVER THE WATERS OVERNIGHT AS A  
WEAK COLD FRONT SHIFTS INTO THE AREA FROM THE NORTH LATE, BEFORE  
STALLING NEAR THE REGION AROUND DAYBREAK. GIVEN THE SETUP,  
STRONGER WIND GUSTS WILL BE POSSIBLE WITH STORMS. OUTSIDE SHOWER  
AND THUNDERSTORM ACTIVITY, A SOUTHERLY WIND IS EXPECTED TO  
REMAIN AROUND 15 KT OR LESS UNTIL TURNING NORTH BEHIND THE FRONT.  
SEAS WILL BE NO HIGHER THAN 3-4 FT.  
 
THURSDAY THROUGH MONDAY: THUNDERSTORMS WILL PRODUCE LOCALLY  
HAZARDOUS CONDITIONS THROUGH THE PERIOD. A COLD FRONT WILL STALL  
OVER THE WATERS THURSDAY AND THURSDAY NIGHT, PUSHING WINDS INTO THE  
EAST/SOUTHEAST AT 15 KT OR LESS. THEN, THE BOUNDARY WILL LIFT NORTH  
AS A WARM FRONT FRIDAY, AND WINDS WILL TURN INTO THE SOUTHWEST AND  
COULD INCREASE INTO THE 15-20 KNOT RANGE AT TIMES THROUGH EARLY NEXT  
WEEK. SEAS ONLY 1-3 FEET THROUGH FRIDAY WILL BUILD TO 3-5 FEET,  
HIGHEST BEYOND 20 NM, THIS WEEKEND INTO EARLY NEXT WEEK.  
 

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

 
 

 
NEAR TERM...DPB  
SHORT TERM...SPR  
LONG TERM...MS  
AVIATION...DPB/NED  
MARINE...DPB/NED  
 
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