365  
FXUS62 KCAE 250013  
AFDCAE  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE COLUMBIA SC  
813 PM EDT THU SEP 24 2020  
   
SYNOPSIS
 
 
MOISTURE ASSOCIATED WITH THE REMNANTS OF TS BETA AND A  
SHORTWAVE TROUGH WILL BRING INCREASING RAIN CHANCES TONIGHT THROUGH  
FRIDAY NIGHT. BRIEF DRYING ALONG WITH SLIGHTLY ABOVE NORMAL  
TEMPERATURES CAN BE EXPECTED FOR THE WEEKEND. RAIN CHANCES MAY  
RETURN ON MONDAY AHEAD OF AN APPROACHING COLD FRONT. A REINFORCING  
COLD FRONT EXPECTED TO PASS THROUGH THE REGION ON WEDNESDAY, WITH  
LIMITED MOISTURE.  
 

 
   
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
 
 
MOISTURE CONTINUES TO OVERSPREAD THE AREA WITH A DEEP SW FLOW. WHILE  
MID AND UPPER LEVEL MOISTURE HAS CONTINUED TO BE PRESENT, THE LOW  
LEVELS ARE NOW STARTING TO MOISTEN WITH DEW POINTS CLIMBING BACK  
INTO THE 60S ACROSS THE AREA. MOISTURE WILL ONLY CONTINUE TO  
INCREASE AS A SOUTHERLY LOW LEVEL JET CONTINUES TO INCREASE  
TONIGHT. LIGHT TO MODERATE SHOWERS WILL CONTINUE WITH THE  
HEAVIEST RAIN TONIGHT IN THE UPSTATE OF SC, CLOSEST TO THE  
SURFACE LOW PRESSURE AND POSITIVE VORTICITY ADVECTION FROM THE  
TROUGH TO THE WEST. SHORTWAVE ENERGY MAY ENHANCE SOME SHOWER  
ACTIVITY AT TIMES TONIGHT ACROSS THE AREA. A WARM FRONT JUST  
SOUTH OF THE AREA WILL STEADILY LIFT NORTH AND WHILE INSTABILITY  
WILL BE LIMITED LATE TONIGHT, SOME HIRES MODELS DO INDICATE THE  
POTENTIAL FOR ISOLATED STORMS DEVELOPING.  
 

 
   
SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/
 
 
PWAT VALUES WILL CONTINUE TO INCREASE FRIDAY AS BETA REMNANTS  
CONTINUE TO MOVE EAST. MODELS ARE IN AGREEMENT OF PWATS AROUND 1.5  
TO 2 INCHES. GREATEST PRECIP AMOUNTS LOOK TO BE IN THE EASTERN  
MIDLANDS, CURRENTLY IN A SLIGHT RISK OF FLASH FLOODING WITH 2-3  
INCHES POSSIBLE, GREATER AMOUNTS IN HEAVY THUNDERSTORMS. SEVERE  
WEATHER REMAINS A THREAT TOMORROW AS WELL. EARLIER MODEL STORM  
RELATIVE HELICITY VALUES WERE AROUND 430, BUT RECENTLY UPDATED  
MODELS HAVE BROUGHT IT DOWN TO AROUND 300 M2/S-2 TOMORROW MORNING.  
HIGHEST CAPE VALUES ARE IN THE WESTERN MIDLANDS AT AROUND 2000 J/KG  
TOMORROW AFTERNOON. LIFTED INDICES HAVE RISEN SINCE LAST UPDATE TO  
AROUND -5.5C. THUNDERSTORMS ARE A GIVEN TOMORROW, SOME SEVERE, WITH  
SOME STRONG WIND GUSTS, MAINLY IN THE AFTERNOON HOURS. HOWEVER,  
THERE STILL REMAINS TO BE SOME UNCERTAINTY OF WHETHER OR NOT  
TORNADOES ARE ALSO A POSSIBILITY.  
 
ECMWF SHOWS MOISTURE LINGERING INTO FRIDAY NIGHT, BUT WENT WITH  
GFS AND NAM AND HAD SHOWERS STARTING TO TAPER OFF BY EARLY  
SATURDAY MORNING. TEMPERATURES TOMORROW AFTERNOON WILL BE NORMAL  
TO SLIGHTLY ABOVE NORMAL FARTHER SOUTH. NIGHTTIME LOWS HIGHER  
THAN CLIMO, CLOSE TO 70.  
 

 
   
LONG TERM /SATURDAY THROUGH THURSDAY/
 
 
STILL A LOT OF UNCERTAINTY IN REGARDS TO THE AMOUNT OF MOISTURE THAT  
WILL BE AVAILABLE AS TWO SEPARATE COLD FRONTS MOVE THROUGH THE  
REGION IN THE LONGER TERM. FOR THE MOST PART, SUNDAY SHOULD BE  
MOSTLY DRY AS UPPER RIDGE MOVES THROUGH THE REGION. MODELS DO SHOW  
SOME MOISTURE ADVECTING NORTHWARD FROM THE GULF OF MEXICO DURING THE  
DAY, BUT THE THAT SHOULD REMAIN JUST SOUTHWEST OF THE FORECAST AREA.  
ONLY EXPECTING ISOLATED AFTERNOON SHOWERS ON SUNDAY. DEEPER  
MOISTURE WILL BE MOVING IN SUNDAY NIGHT INTO MONDAY AHEAD OF THE  
FIRST COLD FRONT. ISOLATED SHOWERS WILL REMAIN POSSIBLE OVERNIGHT  
SUNDAY NIGHT INTO MONDAY MORNING, THEN BETTER RAIN CHANCES AND  
COVERAGE EXPECTED JUST AHEAD OF THE ADVANCING COLD FRONT MONDAY  
AFTERNOON. DRIER AIR WILL PUSH IN BEHIND THAT FIRST COLD FRONT  
MONDAY NIGHT. THE NEXT COLD FRONT SHOULD MOVE THROUGH WEDNESDAY,  
AND THAT'S WHERE THE UNCERTAINTY REALLY EXISTS. FIRST FRONT FROM  
MONDAY SHOULD PUSH THE MAJORITY OF THE MOISTURE OFFSHORE. THE  
QUESTION WILL BE IF THERE WILL BE ANY MOISTURE RETURN AHEAD OF THE  
SECOND FRONT. MODELS ARE AGGRESSIVE WITH MOISTURE AHEAD OF DEEP  
DIGGING UPPER TROUGH. HAVE CONTINUED TO LEAN MORE TOWARDS A DRIER  
SOLUTION FOR NOW FROM WEDNESDAY THROUGH THE END OF THE WEEK.  
 

 
   
AVIATION /00Z FRIDAY THROUGH TUESDAY/
 
 
THE REMNANTS OF TROPICAL CYCLONE BETA OVER NORTH ALABAMA WILL  
MOVE NORTHEAST OVERNIGHT INTO FRIDAY. EXPECT MVFR CEILING  
RESTRICTIONS TO DEVELOP THIS EVENING AS LOW-LEVEL SOUTH  
MOISTURE FLUX INCREASES ACROSS THE AREA AHEAD OF THE CYCLONE.  
AT 00Z, RADAR INDICATING PATCHY SHOWERS WITH ISOLATED AREAS OF  
MODERATE INTENSITY ACROSS THE AREA. ANY VISIBILITY RESTRICTIONS  
SHOULD BE LIMITED THROUGH 06Z. WARM FRONT WILL BE LIFTING  
NORTHWEST THROUGH THE AREA OVERNIGHT. EXPECT LOWERING CEILINGS  
TOWARD MORNING ALTHOUGH CONFIDENCE NOT HIGH ESPECIALLY TO THE  
EAST OF CAE. STRONGER LIFT TOWARD MORNING SUGGESTS MORE SHOWER  
COVERAGE THROUGH MID MORNING. SOME POTENTIAL FOR STRONG  
THUNDERSTORMS LATER IN THE MORNING THROUGH AFTERNOON WITH  
MODERATE INSTABILITY AND RELATIVELY STRONG SHEAR. THE WARM FRONT  
IN THE PIEDMONT MAY BE WHERE THE STORMS DEVELOP THEN MOVE EAST  
THROUGH THE AFTERNOON. SCATTERED COVERAGE EXPECTED AFTER 18Z  
WITH VFR POSSIBLE OUTSIDE STORMS.  
 
EXTENDED AVIATION OUTLOOK...RESTRICTIONS IN FOG/STRATUS  
EXPECTED FRIDAY NIGHT. CHANCE OF SHOWERS WITH LINGERING  
CEILING RESTRICTIONS THRU SATURDAY MORNING. LATE NIGHT/EARLY  
MORNING FOG/STRATUS POSSIBLE SATURDAY AND SUNDAY. DRIER AIR  
COMING IN BEHIND A DRY COLD FRONT WILL LEAD TO EXPECTATIONS OF  
MAINLY VFR CONDITIONS MON/TUE.  
 

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

 
 

 
 
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