357  
FXUS62 KCAE 241843  
AFDCAE  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE COLUMBIA SC  
243 PM EDT MON SEP 24 2018  
   
SYNOPSIS
 
 
A WEAK FRONTAL BOUNDARY STALLED OVER THE MIDLANDS WILL BECOME  
DIFFUSE THIS AFTERNOON. A WEDGE OF MOIST HIGH PRESSURE WILL  
CONTINUE OVER THE REGION INTO THROUGH TUESDAY. ANOTHER FRONT  
WILL MOVE INTO THE REGION LATE WEDNESDAY. THESE FACTORS WILL  
LEAD TO INCREASING PRECIPITATION CHANCES BY MID WEEK BUT  
TEMPERATURES REMAIN ABOVE NORMAL UNTIL NEXT WEEKEND.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
A WEAK FRONTAL BOUNDARY OVER THE MIDLANDS WILL BECOME DIFFUSE  
THIS AFTERNOON. SURFACE HIGH PRESSURE CENTERED OVER NEW ENGLAND  
WILL CONTINUE TO RIDGE INTO THE CAROLINAS AND GEORGIA...BRINGING  
WEDGE-LIKE CONDITIONS. SKIES SHOULD REMAIN CLOUDY ACROSS THE  
NORTH MIDLANDS. AREAS FARTHER SOUTH MAY SEE SOME PEAKS OF SUN.  
 
ISENTROPIC LIFT APPEARS WEAK AND MAINLY IN THE SAVANNAH RIVER  
BASIN WHERE PRECIPITABLE WATER IS HIGHER. THE EASTERLY FLOW IS  
ALSO UPSLOPE IN THIS REGION. WE EXPECT SCATTERED SHOWERS TO  
LINGER ACROSS THE CSRA. CONVERGENCE NEAR THE DISSIPATING FRONT  
COMBINED WITH DIURNALLY DRIVEN WEAK INSTABILITY COULD LEAD TO  
MORE SHOWERS AND PERHAPS A THUNDERSTORM DEVELOPING ACROSS THE  
SOUTHERN MIDLANDS THIS AFTERNOON.  
 
TEMPERATURES SHOULD BE COOLER THAN PREVIOUS DAYS, WITH HIGHS  
RANGING FROM THE UPPER 70S NEAR THE NC/SC BORDER TO THE UPPER  
80S ACROSS THE SOUTHERN MIDLANDS AND CSRA.  
 
THE CHANCE FOR SHOWERS WILL DIMINISH TONIGHT AS INSTABILITY  
DECREASES. LOW LEVEL MOISTURE WILL PRODUCE WIDESPREAD CLOUDS.  
OVERNIGHT LOWS WILL BE IN THE UPPER 60S AND LOWER 70S.  
 

 
   
SHORT TERM /TUESDAY THROUGH WEDNESDAY/
 
 
UPPER RIDGE WILL REMAIN OVER THE WESTERN ATLANTIC ON TUESDAY AND  
WILL WEAKEN ON WEDNESDAY AS UPPER TROUGH OVER THE UPPER MIDWEST  
SHIFTS EAST. A BROAD AREA OF LOW PRESSURE OFF THE SOUTH  
CAROLINA COAST TUESDAY MORNING IS EXPECTED TO MOVE NORTHWARD  
TOWARD THE OUTER BANKS OF NORTH CAROLINA DURING THE DAY,  
ALTHOUGH INCREASING UPPER LEVEL WINDS SHOULD LIMIT ADDITIONAL  
DEVELOPMENT. WEAK HIGH PRESSURE WILL REMAIN OVER THE FORECAST  
AREA ON TUESDAY WITH A DRIER AIRMASS IN PLACE. PWAT VALUES WILL  
BE AROUND 1.5 TO 1.7 INCHES, SO SLIGHT CHANCE POPS APPEAR  
REASONABLE. MOISTURE WILL DEEPEN ON WEDNESDAY AHEAD OF A FRONT  
APPROACHING FROM THE OH/TN VALLEY REGIONS. PWAT VALUES  
INCREASE TO AROUND 1.8 INCHES EAST TO 2.0 INCHES WEST. THE BEST  
CHANCE FOR SHOWERS AND THUNDERSTORMS SHOULD BE WEST CLOSER TO  
THE APPROACHING FRONT AND DEEPER MOISTURE. INSTABILITY APPEARS  
MODERATE WITH LI VALUES AROUND -4 TO -5 DURING THE AFTERNOON.  
HIGH TEMPERATURES ON TUESDAY ARE FORECAST IN THE MID 80S NORTH  
TO AROUND 90 SOUTH AND AROUND 90 ON WEDNESDAY.  
 

 
   
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/
 
 
UPPER LEVEL FLOW WILL BECOME MORE WESTERLY HEADING INTO THE  
WEEKEND WITH BROAD UPPER TROUGHING FLATTENING OVER THE EASTERN  
CONUS. THE FRONTAL BOUNDARY WILL CONTINUE TO APPROACH THE  
FORECAST AREA LATE IN THE WEEK AND MAY STALL OVER THE WEEKEND.  
THE BEST CHANCES FOR RAIN APPEAR TO BE THURSDAY THROUGH  
SATURDAY. ONCE THE FRONT PUSHES THROUGH BY SUNDAY, HIGH  
PRESSURE WILL RETURN FOR EARLY NEXT WEEK. EXPECT A GRADUAL  
COOLING TREND INTO THE WEEKEND AND EARLY NEXT WEEK BEHIND THE  
FRONT.  
 

 
   
AVIATION /18Z MONDAY THROUGH SATURDAY/
 
 
SURFACE HIGH PRESSURE WILL CONTINUE TO RIDGE INTO THE AREA FROM  
THE NORTH PRODUCING WEDGE-LIKE CONDITIONS AND NORTHEAST TO EAST  
WINDS. MVFR CIGS ARE EXPECTED TO LIFT TO VFR THIS AFTERNOON AS  
THE ATMOSPHERIC MIXING INCREASES. SCATTERED SHOWERS AND PERHAPS  
ISOLATED THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AS THE  
ATMOSPHERE BECOMES WEAKLY UNSTABLE. SHOWERS HAVE A BETTER CHANCE  
OF AFFECTING AGS/DNL/OGB...SO HAVE INCLUDED A TEMPO GROUP  
THROUGH EARLY EVENING. SHOWERS WILL BEGIN TO DIMINISH WITH  
SUNSET. GIVEN ABUNDANT LOW LEVEL MOISTURE AND NOCTURNAL  
COOLING...EXPECT MVFR/IFR CONDITIONS TO REDEVELOP AROUND AFTER  
25/06Z. MODELS INDICATE IMPROVING CONDITIONS DURING THE  
AFTERNOON TUESDAY AS DRIER AIR FILTERS INTO THE REGION.  
 
EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE EACH DAY IN  
LATE NIGHT/EARLY MORNING FOG/STRATUS AND MAINLY AFTERNOON AND  
EVENING SHOWERS AND THUNDERSTORMS AS A FRONTAL BOUNDARY STALLS  
ACROSS THE AREA THURSDAY THROUGH SATURDAY.  
 

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

 
 

 
 
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