237  
FXUS62 KGSP 191909  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
309 PM EDT FRI APR 19 2019  
   
SYNOPSIS
 
 
A STRONG COLD FRONT WILL MOVE ACROSS THE FORECAST AREA THROUGH THIS  
EVENING BRINGING SHOWERS AND THUNDERSTORMS TO THE REGION. COOLER  
TEMPERATURES AND LINGERING SHOWERS ARE EXPECTED BEHIND THE FRONT.  
TEMPERATURES WILL WARM AGAIN BY EARLY NEXT WEEK.  
 

 
   
NEAR TERM /THROUGH SATURDAY/
 
 
AS OF 240 PM: A DEEP TROUGH EXTENDS ACROSS THE MISSISSIPPI VALLEY,  
WITH AN EMBEDDED UPPER LOW CENTERED OVER NORTHERN MISSISSIPPI. THIS  
FEATURE WILL DRIVE A COLD FRONT INTO THE AREA FROM THE WEST AND  
SOUTHWEST THIS EVENING. WITHIN A MOIST AND MODERATELY UNSTABLE  
AIRMASS OVER OUR AREA, AND THE STRONGLY DIVERGENT FLOW ALOFT  
DOWNSTREAM OF THE TROUGH, WIDESPREAD CONVECTION WILL AFFECT THE  
CWFA THIS AFTERNOON. WITH STRONG GRADIENT FLOW ALOFT, EXCEPTIONALLY  
STRONG LOW-LEVEL SHEAR WILL CONTINUE TO SUPPORT A DAMAGING WIND AND  
TORNADO THREAT. A TORNADO WATCH REMAINS IN EFFECT FOR MOST OF THE  
PIEDMONT. CURRENTLY THE MOST SIGNIFICANT CIRCULATIONS ARE PRESENT  
IN DISCRETE CELLS MOVING THRU THE SOUTHEASTERN CWFA, WHERE SBCAPE  
EXCEEDS 1000 J/KG, SCP EXCEEDS 8, AND STP IS AS HIGH AS 3. FURTHER  
WEST, AHEAD OF THE COLD FRONT, A SQUALL LINE HAS FORMED. WHILE  
NOT CURRENTLY SEVERE, THE LINE IS BEING MONITORED CLOSELY FOR  
QLCS CHARACTERISTICS, ON ACCOUNT OF THE STRONG SHEAR. SUFFICIENT  
INSTABILITY EXISTS UPSTREAM OF THAT LINE, BENEATH THE COLDER AIR  
ALOFT, THAT A SECOND LINE HAS FORMED ACROSS GA. EARLIER HRRR RUNS  
INDICATED THAT SUCH A SECONDARY POCKET OF ACTIVITY COULD SWING  
THROUGH OUR AREA LATE IN THE DAY IF NOT DURING THE EVENING, AND  
WHILE THE LATEST RUN DOESN'T SHOW ANYTHING PARTICULARLY ORGANIZED  
AT THAT TIME, POPS HAVE BEEN KEPT FAIRLY HIGH UNTIL AFTER THE LOSS  
OF DIURNAL HEATING. THE TORNADO WATCH CURRENTLY RUNS UNTIL 5 PM,  
BUT WE MAY BE ABLE TO CLEAR SOME COUNTIES FROM THE WATCH FOLLOWING  
THE WELL-DEFINED SQUALL LINE.  
 
FORCING AND TO SOME EXTENT MOISTURE TAPER OFF OVERNIGHT, BUT FALLING  
HEIGHTS OVER THE MOUNTAINS SUGGEST PRECIP MAY REDEVELOP THERE. THE  
LOW WILL BEGIN TO MOVE NORTHEAST AND ACROSS THE APPALACHIANS. AS  
TEMPS DROP BEHIND THE COLD FRONT, THERE IS POTENTIAL FOR THE COLDEST  
SPOTS (HIGH ELEVATIONS) TO SEE THIS PRECIP CHANGE FROM RAIN TO  
SNOW. SLRS WILL NOT BE PARTICULARLY GOOD OWING TO SHALLOW MOISTURE  
PRESENT AT THAT TIME, AND LOW-LEVEL FLOW REMAINS SOUTHWESTERLY,  
THUS BEING LESS FAVORABLE FOR UPSLOPE FORCING ON THE MAJORITY OF  
THE RIDGES. CONDITIONS LOOK MUCH MORE FAVORABLE AFTER DAYBREAK,  
WHEN THE COLUMN SATURATES OVER A DEEP LAYER BENEATH THE CORE OF  
THE UPPER LOW. MOST OF THE AREA WILL BE SUBJECT TO SCATTERED LIGHT  
RAIN SHOWERS DURING THE DAY AS A RESULT. HOWEVER, IN VERY HIGH  
ELEVATIONS (ALMOST ENTIRELY ABOVE 5000 FT) WILL COOL EARLY ENOUGH,  
AND REMAIN COLD LONG ENOUGH, THAT ACCUMULATING SNOW OF SEVERAL  
INCHES IS POSSIBLE. THESE AREAS CURRENTLY APPEAR TOO SMALL/ISOLATED  
TO WARRANT A WINTER WEATHER ADVISORY. CAN'T ABSOLUTELY RULE OUT  
SOME EVAPORATIVE COOLING THAT WILL ALLOW A FEW FLURRIES TO BE  
EXPERIENCED IN POPULATED AREAS OF THE MOUNTAINS AND FOOTHILLS  
DURING THE MORNING.  
 

 
   
SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/
 
 
AS OF 230 PM EDT FRIDAY: THE MID LEVEL LOW PRESSURE SYSTEM WILL  
PIVOT JUST NORTH OF THE AREA ON SATURDAY NIGHT BEFORE PULLING AWAY  
TO THE NORTHEAST ON SUNDAY. LINGERING WRAP AROUND SHOWERS WILL  
MAINLY IMPACT THE MOUNTAINS ON SATURDAY NIGHT. SOME SNOW IS EXPECTED  
AT THE HIGHER ELEVATIONS ON SATURDAY NIGHT WITH AROUND 1  
ACCUMULATIONS EXPECTED AT THE HIGHEST ELEVATIONS.  
 
A DRYING AND WARMING TREND WILL OCCUR SUNDAY NIGHT AND MONDAY AS  
HIGH PRESSURE BUILDS INTO THE AREA.  
 

 
   
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
 
 
AS OF 200 PM EDT FRIDAY: MID LEVEL RIDGING AND SURFACE HIGH PRESSURE  
WILL BE IN PLACE ACROSS THE REGION FOR TUESDAY AND WEDNESDAY.  
CONDITIONS SHOULD BE DRY AND WARM WITH HIGHS REACHING INTO THE LOWER  
80S IN THE PIEDMONT BY WEDNESDAY. A MID LEVEL TROF AND ASSOCIATED  
COLD FRONT WILL APPREACH THE AREA FROM THE NORTHWEST LATE IN THE  
WEEK WITH AN INCREASING CHANCE OF SHOWERS.  
 

 
   
AVIATION /19Z FRIDAY THROUGH WEDNESDAY/
 
 
AT KCLT AND ELSEWHERE: MULTIPLE ROUNDS OF CONVECTION WILL AFFECT  
AVIATION ACROSS THE REGION THIS AFTN AND EARLY EVENING. FOR KCLT  
AND KHKY IMPACTS MOST LIKELY WILL COME FROM A BAND OF MOSTLY  
STRATIFORM RA WITH EMBEDDED TSRA. KGSP AND KGMU WILL START OFF  
DRY AND VFR, BUT A WELL DEVELOPED QLCS WILL PUSH THRU EARLY IN  
THE PERIOD, POSSIBLY SURVIVING TO KHKY/KCLT. THE SHRA/TSRA ARE  
LIKELY TO BRING BRIEF GUSTS ABOVE 30 KT, MAINLY OUT OF THE W OR  
SW. THE QLCS POSES A RISK OF DAMAGING WIND AND A TORNADO CANNOT BE  
RULED OUT ALONG IT. EVEN FOLLOWING THE DEPARTURE OF THESE EVENTS,  
AN UPPER LOW PASSING NEAR THE AREA THIS EVENING MAY ACCESS ENOUGH  
REMNANT INSTABILITY TO DRIVE A FEW SHOWERS AND POSSIBLY TSRA,  
WHICH WOULD STILL BE CAPABLE OF AT LEAST GUSTY WINDS. MAINLY  
MVFR CIGS ARE EXPECTED THRU TONIGHT, WITH IFR TO LIFR VSBY LIKELY  
WITH THE STRONGER TSRA. A CONTINUING CHANCE FOR SHRA (EVEN SHSN  
IN VERY HIGH ELEVATIONS) EXISTS OVERNIGHT ACROSS THE MTNS, WITH  
WINDS REMAINING BREEZY ACROSS THE REGION. THE UPPER LOW WILL DRIFT  
ACROSS THE AREA DURING THE DAY AND ISO/SCT SHRA SHOULD REDEVELOP  
ACROSS THE PIEDMONT, PERHAPS BRINGING MVFR CIGS/VSBY.  
 
OUTLOOK: MAINLY VFR CONDITIONS ARE EXPECTED SUNDAY AND EARLY  
NEXT WEEK.  
 
CONFIDENCE TABLE...  
 
19-01Z 01-07Z 07-13Z 13-18Z  
KCLT MED 76% MED 75% MED 71% LOW 59%  
KGSP HIGH 85% HIGH 80% MED 68% HIGH 84%  
KAVL HIGH 84% HIGH 90% MED 71% HIGH 83%  
KHKY MED 71% HIGH 89% MED 72% HIGH 85%  
KGMU HIGH 80% HIGH 82% MED 68% HIGH 86%  
KAND HIGH 82% HIGH 84% MED 76% 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:  
 
WWW.WEATHER.GOV/GSP/AVIATION  
 

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

 
 

 
SYNOPSIS...SW  
NEAR TERM...WIMBERLEY  
SHORT TERM...SW  
LONG TERM...SW  
AVIATION...WIMBERLEY  
 
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