261  
FXUS62 KCAE 221804 CCA  
AFDCAE  
 
AREA FORECAST DISCUSSION...CORRECTED  
NATIONAL WEATHER SERVICE COLUMBIA SC  
204 PM EDT MON MAY 22 2017  
   
SYNOPSIS
 
 
A FRONTAL BOUNDARY WILL STALL NEAR THE FORECAST AREA TODAY  
THROUGH TUESDAY, WITH SHOWERS AND THUNDERSTORMS LIKELY IN ADVANCE  
OF THE FRONT. THE COLD FRONT WILL FINALLY BE MOVING EAST OF THE  
REGION BY THURSDAY, WITH DRIER AND COOLER AIR TAKING HOLD FOR THE  
END OF THE WEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AN UPPER LEVEL TROUGH WILL CONTINUE TO DEEPEN OVER THE CENTRAL  
AND EASTERN CONUS. A STALLED FRONTAL BOUNDARY LOCATED ACROSS NC  
LEAVING THE LOCAL AREA IN THE WARM SECTOR AHEAD OF AN APPROACHING  
COLD FRONT. LIFTED INDEX VALUES ARE AROUND -5 AND SURFACE BASED  
CAPE IS NEAR 3000 J/KG. SCATTERED SHOWERS AND THUNDERSTORMS HAVE  
DEVELOPED AND COVERAGE WILL INCREASE THIS EVENING. SHEAR IS ONLY  
AROUND 25 KTS, BUT SPC HAS THE ENTIRE AREA OUTLOOKED FOR A  
MARGINAL RISK OF SEVERE STORMS, WITH STRONG WINDS BEING THE  
BIGGEST THREAT. ADDITIONALLY, PRECIPITABLE WATER VALUES AROUND 2  
INCHES WILL ALLOW FOR WIDESPREAD MODERATE RAIN, WITH LOCALLY HEAVY  
RAIN POSSIBLE. SEVERAL FLASH FLOOD WARNINGS AND ADVISORIES HAVE  
ALREADY BEEN ISSUED. PERIODIC HEAVY RAIN CAN BE EXPECTED THROUGH  
THE NIGHT, AND BASED ON HEAVY RAIN POTENTIAL A FLASH FLOOD WATCH  
WILL REMAIN IN EFFECT FOR THE ENTIRE AREA THROUGH WEDNESDAY NIGHT.  
 
AFTERNOON HIGH WILL BE GENERALLY BE IN THE 80S WITH OVERNIGHT LOWS  
IN THE 60S. WINDS WILL MOSTLY BE LIGHT AND SOUTHERLY, EXCEPT  
GUSTY AND ERRATIC IN VICINITY OF SHOWERS AND THUNDERSTORMS.  
 

 
   
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
 
 
FLASH FLOOD WATCH POSTED DUE TO INCREASED THREAT FOR HEAVY RAIN  
ASSOCIATED WITH STALLED FRONTAL BOUNDARY AND ANOMALOUSLY HIGH  
PRECIPITABLE WATER. THERE IS ALSO A MARGINAL RISK OF SEVERE  
THUNDERSTORMS ESPECIALLY IN THE SOUTH MIDLANDS AND CSRA  
ASSOCIATED WITH STRENGTHENING LOW LEVEL JET 40 TO 50 KTS EARLY  
IN THE DAY AND POSSIBLE WEAK MESO-LOW TRACKING NORTHEAST ALONG  
THE FRONT THROUGH THE AFTERNOON...  
 
UPPER TROUGH OVER THE UPPER MIDWEST DIVING SOUTHEAST INTO THE  
LOWER MISSISSIPPI VALLEY DURING THE PERIOD. SEVERAL SHORT WAVE  
TROUGHS WILL ROTATE THROUGH THE BASE OF THE TROUGH AND TRACK  
NORTHEAST INTO THE CAROLINAS AND GEORGIA. THE SURFACE FRONTAL  
BOUNDARY WILL MOVE INTO CENTRAL SC AND EAST CENTRAL GEORGIA  
EARLY TUESDAY. THE MODELS APPEAR TO SUGGEST A SURGE OF MOISTURE  
EARLY IN THE DAY WITH PRECIPITABLE WATER NEAR 2 INCHES. SHORT  
WAVE TROUGH MOVING THROUGH THE AREA ALONG WITH A WEAK SURFACE  
LOW/MESO LOW SHOULD LEAD TO NUMEROUS SHOWERS AND A FEW  
THUNDERSTORMS IN THE MORNING THROUGH EARLY AFTERNOON. A FEW OF  
THESE STORMS MAY BE SEVERE...ESPECIALLY SOUTH OF THE FRONT IN  
THE SOUTH MIDLANDS AND CSRA. CONCERN WITH ENHANCED 0-1 KM SR  
HELICITY SOUTHEAST THROUGH THE AFTERNOON. BUT THE MAIN THREAT  
REMAINS HEAVY RAIN DUE TO TRAINING OF STORMS NEAR STALLED FRONT.  
WPC HAS REGION IN SLIGHT RISK OF EXCESSIVE RAINFALL. THERE MAY  
BE A LULL LATE IN THE DAY AS STRONGER SHORT WAVES MOVE TO THE  
NORTH AND EAST. HOWEVER...AIR MASS WILL BE MODERATELY UNSTABLE  
AND FRONT REMAINS IN THE AREA FOCUSING LOW LEVEL CONVERGENCE.  
THE FRONT MAY MOVE NORTH TO NEAR THE SC/NC BORDER DURING THE  
OVERNIGHT AND THE RAIN MAY DIMINISH SOMEWHAT AS SHORT WAVES MOVE  
TO THE NORTHEAST...BUT AIR MASS REMAINS MOIST AND UNSTABLE.  
 
ANOTHER SURGE OF MOISTURE ON WEDNESDAY AHEAD OF COLD FRONT AND  
THE FLASH FLOOD THREAT CONTINUES ALONG WITH MARGINAL SEVERE  
WEATHER THREAT. MOS GUIDANCE CONSENSUS USED FOR TEMPERATURES.  
 
QPF AMOUNTS THROUGH WEDNESDAY NIGHT OF 2.5 TO 3 INCHES WITH  
LOCALLY HIGHER AMOUNTS.  
 

 
   
LONG TERM /THURSDAY THROUGH MONDAY/
 
 
THE FRONT SHOULD BE EAST OF THE AREA THURSDAY, BUT WITH COLD  
TEMPERATURES ALOFT THE AREA MAY STILL SEE ISOLATED SHOWERS  
THROUGH THE AFTERNOON. DRIER AND COOLER AIR SHOULD THEN SPREAD  
OVER THE REGION FOR THE END OF THE WEEK BUT WARMING AGAIN BY  
WEEKEND. A FRONT TO THE NORTH MAY MOVE SOUTH INTO THE AREA LATE  
IN THE WEEKEND RESULTING IN ISOLATED AFTERNOON CONVECTION.  
 

 
   
AVIATION /18Z MONDAY THROUGH SATURDAY/
 
 
VARIABLE CONDITIONS THROUGH THE TAF PERIOD.  
 
WITH A FRONTAL BOUNDARY APPROACHING FROM THE WEST AND DEEP  
MOISTURE ACROSS THE AREA, SCATTERED TO WIDESPREAD SHOWERS AND  
THUNDERSTORMS WILL CONTINUE THIS EVENING. RAIN CHANCES WILL  
INCREASE OVERNIGHT WITH STEADY RAIN EXPECTED THROUGH TUESDAY  
MORNING. RESTRICTIONS WILL BE VARIABLE AND IFR CONDITIONS CAN BE  
EXPECTED AT TIMES IN MODERATE TO HEAVY RAIN. GUSTY WINDS AND  
FREQUENT LIGHTNING CAN ALSO BE EXPECTED THIS EVENING IN STORMS.  
 
EXTENDED AVIATION OUTLOOK...RESTRICTIONS EXPECTED IN SCATTERED  
TO WIDESPREAD CONVECTION TUESDAY THROUGH THURSDAY.  
 

 
   
HYDROLOGY
 
 
WITH AREAS OF HEAVY RAIN POSSIBLE ACROSS THE RIVER BASIN IN THE  
UPSTATE AND MIDLANDS DURING THE NEXT 24-36 HRS MODERATE RISES  
ARE EXPECTED ON THE AREA RIVERS. THIS MAY LEAD TO RIVER FLOODING  
AND WILL BE MONITORED CLOSELY.  
 

 
   
CAE WATCHES/WARNINGS/ADVISORIES
 
 
GA...FLASH FLOOD WATCH THROUGH THURSDAY MORNING FOR GAZ040-063>065-  
077.  
SC...FLASH FLOOD WATCH THROUGH THURSDAY MORNING FOR SCZ015-016-018-  
020>022-025>031-035>038-041.  
 

 
 

 
 
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