142  
FXUS62 KGSP 201759  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
159 PM EDT SAT APR 20 2019  
   
SYNOPSIS
 
 
AN UPPER LEVEL LOW PRESSURE CENTER LOCATED NEAR WEST VIRGINIA WILL  
MOVE SLOWLY EAST THROUGH MONDAY. EXPECT A WARMING TREND AS AS THE  
UPPER LOW MOVES AWAY FROM OUR AREA. WARM AND DRY HIGH PRESSURE WILL  
BE IN CONTROL OF OUR WEATHER FOR MOST OF THE WEEK. RAIN CHANCES  
INCREASE BY THE END OF THE WEEK AS A COLD FRONT MOVES INTO OUR AREA.  
 

 
   
NEAR TERM /THROUGH SUNDAY/
 
 
AS OF 200 PM...CLOSED UPPER LOW IS NOW CENTERED ON THE SOUTHERN  
APPALACHIANS, WITH AN AXIS OF VORTICITY ORIENTED ALONG THE I-26  
CORRIDOR. ALONG AND AHEAD OF THIS AXIS, A SMALL AMOUNT OF SBCAPE  
(PROBABLY 100 J/KG OR LESS) WIDESPREAD SHOWER ACTIVITY WILL  
CONTINUE, PRODUCING A FEW HUNDREDTHS OF AN INCH OF RAIN BY THE  
END OF THE DAY. ALL AREAS AT LEAST POTENTIALLY WILL SEE A FEW  
SPRINKLES. RAP PROFILES SUGGEST THE CONVECTIVE LAYER REACHES UP  
TO ICY TEMPS. THUS A FEW STRONGER CELLS PRODUCING GRAUPEL AND EVEN  
MAYBE A LITTLE THUNDER CAN BE EXPECTED IN THE AREA NE OF I-26.  
 
MORE DETAILS WILL BE INCLUDED WITH THE FULL AFTN PACKAGE WITHIN  
THE NEXT HOUR.  
 

 
   
SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/
 
 
AS OF 120 PM EDT SATURDAY...IT LOOKS LIKE WE WILL SEE A RETURN  
TO WARMER TEMPERATURES DURING THE EARLY PART OF THE UPCOMING  
WEEK. THE OLD UPPER LOW WILL ROTATE OFF THE MID-ATLANTIC COAST  
ON SUNDAY NIGHT, ALLOWING SFC HIGH PRESSURE TO BUILD IN FROM THE  
NW. THE ARRIVAL OF THE HIGH WILL PROVIDE US WITH ONE MORE COOL  
MORNING ON MONDAY, BUT THE AIR MASS SHOULD MODIFY QUICKLY AS  
A FLATTENING UPPER RIDGE BUILDS IN DURING THE DAY. AS A RESULT,  
TEMPERATURES REBOUND ANOTHER 5-10 DEGREES COMPARED TO SUNDAY. AFTER  
A MILD MONDAY NIGHT, THE TEMPS ON TUESDAY LOOK EVEN WARMER...ON  
THE ORDER OF TEN DEGREES ABOVE NORMAL...WITH HIGH PRESSURE MOVING  
OFF THE SOUTHEAST COAST. WE COULD EVEN HAVE A FEW SHOWERS POPPING  
UP ALONG THE RIDGETOPS ACROSS THE MTNS OF NC IN THE AFTERNOON.  
 

 
   
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
 
 
AS OF 2PM EDT SATURDAY: EC AND GFS GENERALLY AGREE ON LOW POPS  
THROUGH WED. NIGHT AS BROAD EASTERN UPPER RIDGE CONTINUES TO HOLD  
SWAY. BY THURSDAY MORNING, THE GFS BEGINS TO WASH-OUT THE RIDGE AND  
ALLOWS A WEAK FRONTAL BOUNDARY INTO THE MOUNTAINS, GIVING SOME  
INCREASE IN RAIN CHANCES AT THAT TIME, WHICH LAST THROUGH SATURDAY  
MORNING AS FRONT AND UPPER SOUTHERN-STREAM LOW ADVANCES INTO THE  
REGION. EC, ON THE OTHER HAND, KEEPS THE RIDGE STRONGER THROUGH  
FRIDAY MORNING, WITH A MORE PRONOUNCED SOUTHERN STREAM WAVE  
BEGINNING TO POP PRECIP ON FRIDAY. RESULTING BLEND WILL BE SOME  
INCREASE IN SHOWER POSSIBILITIES BEGINNING THURSDAY, AND LASTING  
THROUGH SATURDAY MORNING. RIDGE WILL GIVE ABOVE NORMAL TEMPS. UNTIL  
PRECIPITATION DEVELOPS LATE IN THE FORECAST. LOW TEMPERATURES ARE  
SOMEWHAT MORE UNCERTAIN DUE TO DIFFERENCES OF OPINION IN THE AMOUNT  
OF MOISTURE RETAINED UNDER THE RIDGE, AND CONSIDERABLE DIFFERENCES  
IN MODEL INDICATIONS OF HOW MUCH MOISTURE ADVANCES AHEAD OF THE NEXT  
SYSTEM LATE IN THE WEEK. NONETHELESS, LOWS SHOULD BE AT OR ABOVE  
SEASONAL NORMALS THROUGHOUT THE FORECAST, KEEPING ANY FROST OUT OF  
THE PICTURE. WINDS SHOULD BE FAIRLY LIGHT UNDER THE RIDGE WED. INTO  
THURS., AND MAY PICKUP AS SURFACE LOW BEGINS TO IMPACT THE REGION  
LATE IN THE FORECAST.  
 
GFS DEVELOPS MEAGER CAPE THURS. - FRI., GIVING SOME CHANCE FOR  
THUNDER WITH THE LATE-PERIOD FRONT; HOWEVER, IF THE EC IS CORRECT  
WITH A STRONGER LOW AND AN OPEN GULF, BETTER INSTABILITY AND A  
CHANCE FOR STRONGER STORMS COULD DEVELOP FOR FRIDAY.  
 

 
   
AVIATION /18Z SATURDAY THROUGH THURSDAY/
 
 
AT KCLT AND ELSEWHERE: AN UPPER LOW SKIRTING BY THE REGION WILL  
PROVIDE ENHANCED LAPSE RATES AND FORCING, GENERATING LIGHT SHOWERS  
ACROSS THE PIEDMONT THIS AFTERNOON. SOME OF THESE SHRA WILL BRING  
MVFR CIGS/VSBY. OCCASIONAL BRISK GUSTS COULD OCCUR IN THEIR VICINITY  
AS WELL. THE POSSIBILITY OF LIGHT NONCONVECTIVE PRECIP WILL PERSIST  
ACRS THE MOUNTAINS INTO TONIGHT. VERY HIGH ELEVATIONS WILL SEE  
LIGHT SNOWFALL THIS AFTN/EVENING, BUT MOST LIKELY NOT REACHING  
THE VALLEYS OR KAVL. CLOUDS WILL BECOME MORE SPARSE AFTER SUNSET  
EAST OF THE MTNS. WHILE CONDITIONS WILL REMAIN VFR THEREAFTER,  
SOME CONGESTED CUMULUS MAY REDEVELOP IN THE LATE MORNING TOMORROW,  
ALBEIT WITH NEAR-ZERO CHANCE OF PRECIP. WINDS WILL REMAIN SW AND  
SOMEWHAT GUSTY THIS AFTN, VEERING TO NW OVERNIGHT.  
 
OUTLOOK: VFR CONDS ARE EXPECTED TO PREVAIL THRU EARLY NEXT WEEK.  
 
CONFIDENCE TABLE...  
 
18-24Z 00-06Z 06-12Z 12-18Z  
KCLT HIGH 100% HIGH 99% HIGH 100% HIGH 100%  
KGSP HIGH 93% HIGH 100% HIGH 100% HIGH 100%  
KAVL HIGH 85% HIGH 85% MED 69% HIGH 94%  
KHKY HIGH 98% HIGH 99% HIGH 100% HIGH 100%  
KGMU HIGH 90% HIGH 100% HIGH 100% HIGH 100%  
KAND HIGH 89% HIGH 100% HIGH 100% HIGH 100%  
 
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:  
 
WWW.WEATHER.GOV/GSP/AVIATION  
 

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

 
 

 
SYNOPSIS...DEO  
NEAR TERM...WIMBERLEY  
SHORT TERM...PM  
LONG TERM...WJM  
AVIATION...WIMBERLEY  
 
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