249  
FXUS62 KGSP 241655  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
1255 PM EDT THU APR 24 2014  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL MOVE OFF THE EASTERN SEABOARD TONIGHT AS A COLD  
FRONT AND UPPER LEVEL DISTURBANCE APPROACH FROM THE WEST. THE COLD  
FRONT WILL CROSS THE AREA ON FRIDAY...WITH DRY HIGH PRESSURE  
RETURNING THROUGH THE WEEKEND. A WET AND POSSIBLY STORMY PATTERN  
WILL SET UP MONDAY THROUGH WEDNESDAY...FOLLOWED BY COOLER WEATHER.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
1700 UTC UPDATE...SKY COVER WAS UPDATED FROM VISIBLE SATELLITE  
IMAGERY. WINDS WERE UPDATED WITH A BLEND OF THE LATEST NAM AND  
ADJMAV.  
 
AT 1015 EST THURSDAY...A LOW AMPLITUDE UPPER RIDGE EXTENDED FROM THE  
GULF OF MEXICO TO THE GREAT LAKES...WITH TROUGHS OFF THE EAST COAST  
AND OVER THE GREAT PLAINS. A STATIONARY FRONT WAS LOCATED ALONG THE  
GULF COAST...AND A COLD FRONT OVER THE PLAIN.  
 
SURFACE HIGH PRESSURE WAS LOCATED ALONG THE EASTERN SEABOARD...AND  
IS PROJECTED TO PUSH OFF THE COAST THIS AFTERNOON. SATELLITE IMAGERY  
SHOWED A CLEAR SKY OVER NE GA AND THE WESTERN CAROLINAS. MODEL TIME  
HEIGHTS SUGGEST A SLIGHT INCREASE IN CLOUDS COVER AS WINDS VEER TO  
THE SE AND LOW LEVEL MOISTURE STARTS TO INCREASE...BUT NO  
PRECIPITATION IS EXPECTED.  
 
HIGH RES MODELS GENERALLY AGREE THAT ORGANIZED CONVECTION ASSOCIATED  
WITH THE APPROACHING COLD FRONT WILL MAKE A RUN A THE NC MTNS  
OVERNIGHT. THE STORMS LOOK TO TAKE ON A LINEAR MODE...BUT LOSE STEAM  
AS THEY CROSS ERN TENN DURING THE WEE MORNING HOURS. THE DAY 1  
CONVECTIVE OUTLOOK FROM SPC DOES SHOW A SLGT RISK TO OUR WEST...WITH  
GENERAL THUNDER RISK FROM CENTRAL TN TO THE NC MTNS. I WILL KEEP  
SOME POPS CREEPING INTO THE WRN ZONES LATE TNGT...WITH THE EXPECTED  
ARRIVAL OF AT LEAST WEAKENED SHWRS TO THE SMOKIES BEFORE DAYBREAK  
FRIDAY. OTHERWISE...EXPECT AN INCREASE IN CLOUDS...AND TEMPS ONLY  
DROPPING INTO THE 50S MOST PLACES.  
 

 
   
SHORT TERM /FRIDAY THROUGH SUNDAY/
 
 
AS OF 300 AM EDT THU...A DEAMPLIFYING BUT COHERENT MID LEVEL  
SHORTWAVE TROUGH WILL MOVE QUICKLY EAST THROUGH THE WRN CAROLINAS ON  
FRI. DECAYING CONVECTION MAY BE IN PLACE ACROSS THE MOUNTAINS AS THE  
PERIOD BEGINS FRI MORNING...BUT ADDITIONAL SHOWER AND TSTM  
DEVELOPMENT IS LIKELY ACROSS THE FOOTHILLS AND PIEDMONT THROUGH MID  
AFTERNOON PRIOR TO FROPA. THE BEST INSTABILITY SHOULD LINE UP OVER  
SE PIEDMONT SECTIONS FRI AFTN...WITH 0 TO 3 KM BULK SHEAR VALUES  
AROUND 30 KT. THIS MIGHT BE JUST ENOUGH FOR THUNDERSTORM  
ORGANIZATION...BUT PROBABLY NOT ENOUGH FOR A SIGNIFICANT SEVERE WX  
THREAT. SCATTERED SHOWERS MAY LINGER ACROSS THE WRN MTNS INTO EARLY  
FRI EVENING IN BRIEF MOIST UPSLOPE FLOW.  
 
UPPER LEVEL RIDGING WILL THEN BUILD OVER THE ERN CONUS AND  
STRENGTHEN THROUGH THE WEEKEND. THERE SEEMS TO BE SLIGHTLY BETTER  
CONSENSUS ON AN APPROACHING BACK DOOR COLD FRONT STALLING N OF THE  
REGION OVER VA THROUGH SUNDAY. DESPITE THE WEAK FROPA ON FRI...MAXES  
WILL BE HIGHER SAT AND SUNDAY IN BETTER INSOLATION.  
 

 
   
LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/
 
 
AS OF 300 AM EDT THU...A DEEP LOW PRESSURE SYSTEM OVER THE CENTRAL  
PLAINS BY THE END OF THE WEEKEND WILL GRADUALLY FILL AS IT WOBBLES  
EWD TOWARD THE MIDWEST MON THROUGH WED. THE DOWNSTREAM RIDGE AXIS  
WILL MOVE TO THE ERN SEABOARD SUNDAY NIGHT...WITH HEIGHTS FALLING  
THROUGH THE REMAINDER OF THE LONG TERM PERIOD. GRADUALLY BUILDING SW  
FLOW AND BANDS OF MOISTURE AND LIFT EJECTING EASTWARD FROM THE DEEP  
VORTEX WILL BE HARD TO TIME THROUGH THE PERIOD. THE BEST MOISTURE  
AND UPPER SUPPORT SHOULD LEAN TOWARD THE TUE THROUGH WED PERIOD AS A  
BETTER UPPER JET STRUCTURE EAST OF THE CLOSED SYSTEM WILL LIKELY BE  
IN PLACE NEAR THE APPALACHIANS. PERIODS OF HEAVY RAIN WILL BE  
POSSIBLE AT SOME POINT...PROBABLY TUE OR WED...BUT THAT TIMING  
CANNOT BE PINNED DOWN YET. EXPECT SLIGHTLY ABOVE NORMAL TEMPS ON  
MONDAY...NEAR CLIMO TUE...AND LOWER THAN NORMAL MAXES BY WED.  
 

 
   
AVIATION /18Z THURSDAY THROUGH TUESDAY/
 
 
KCLT...WINDS WILL VEER SE SOON...STAYING THERE UNTIL FRI MORNING  
WHEN THE VEER THE E. MVFR CIG ARRIVES AFTER MIDNIGHT AS LOW LEVEL  
MOISTURE INCREASES AHEAD OF A COLD FRONT...THEN IFR BEFORE DAYBREAK.  
GUIDANCE DOES NOT SUPPORT A VSBY RESTRICTION. MVFR RETURNS AFTER  
DAYBREAK. THE BEST BET FOR THUNDERSTORMS APPEARS TO BE TOWARD MIDDAY  
WITH BETTER INSTABILITY.  
 
ELSEWHERE...CLOUDS OVER WILL BE SLOW TO INCREASE...BY AFTER MIDNIGHT  
GUIDANCE SUGGESTS MVFR CIGS AS MOISTURE INCREASES AHEAD OF AN  
APPROACHING COLD FRONT...FALLING TO IFR BEFORE DAWN. CIGS RETURN TO  
MVFR AFTER DAYBREAK. GUIDANCE IS NOT SUPPORTIVE OF FOG BASED VSBY  
RESTRICITONS. ALTHOUGH A WIDE WINDOW FOR PRECIPITATION WILL EXIST  
FROM DAYBREAK ON...THE BEST BET IS LATER IN THE MORNING WITH BETTER  
INSTABILITY. WINDS WILL VEER SE THIS AFTERNOON...AND SSW EARLY  
FRIDAY.  
 
OUTLOOK...A COLD FRONT WITH POTENTIAL FOR SHOWERS/TSTMS IS EXPECTED  
TO CROSS THE REGION FRIDAY. THEN DRY HIGH PRES RETURNS SATURDAY THRU  
SUNDAY. INCREASED MOISTURE RETURNS TO THE REGION EARLY NEXT WEEK.  
 
CONFIDENCE TABLE...  
 
17-23Z 23-05Z 05-11Z 11-17Z  
KCLT HIGH 100% HIGH 100% MED 73% HIGH 90%  
KGSP HIGH 100% HIGH 100% MED 75% HIGH 98%  
KAVL HIGH 100% HIGH 100% HIGH 90% HIGH 84%  
KHKY HIGH 100% HIGH 100% HIGH 84% HIGH 84%  
KGMU HIGH 100% HIGH 100% HIGH 83% HIGH 97%  
KAND HIGH 100% HIGH 100% MED 77% HIGH 94%  
 
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING  
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE  
HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE  
FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)  
 
WWW.WEATHER.GOV/GSP/AVIATION_TABLES  
 

 
   
GSP WATCHES/WARNINGS/ADVISORIES
 
 
GA...NONE.  
NC...NONE.  
SC...NONE.  
 

 
 

 
SYNOPSIS...HG  
NEAR TERM...ARK/JAT  
SHORT TERM...HG  
LONG TERM...HG  
AVIATION...JAT  
 
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