926  
FXUS62 KGSP 260238  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
1038 PM EDT SUN OCT 25 2020  
   
SYNOPSIS
 
 
COOL HIGH PRESSURE WILL BUILD SOUTH INTO THE REGION THROUGH  
TONIGHT, THEN WEAKEN ON MONDAY AS COOL TEMPERATURES LINGER. EXPECT A  
RETURN TO ABOVE NORMAL TEMPERATURES FOR TUESDAY AND WEDNESDAY BEFORE  
THE NEXT ROUND OF RAIN APPEARS BY THURSDAY AHEAD OF A STRONG UPPER  
LOW. AS THIS LOW MOVES OFF THE EAST COAST LATE FRIDAY, COOL, DRY  
HIGH PRESSURE WILL DROP TEMPERATURES A LITTLE BELOW NORMAL FOR NEXT  
WEEKEND.  
 

 
   
NEAR TERM /THROUGH MONDAY/
 
 
AS OF 1030 PM EDT: RADAR ECHOES HAVE REALLY DIMINISHED OVER THE  
LAST COUPLE OF HOURS, BUT THERE IS STILL A FEW PATCHES OF DRIZZLE  
OUT THERE, ESPECIALLY NEAR THE ESCARPMENT. THE POPS/WX WERE UPDATED  
TO REFLECT THE LOWER COVERAGE, WITH MAINLY JUST SLGT CHC TO LOW-END  
CHC FOR THE NEXT FEW HOURS. ALSO MADE SOME TWEAKS TO THE TEMP TRENDS  
TO LINE UP WITH OBS.  
 
OTHERWISE, THE UPPER SHORTWAVE WILL CONTINUE TO MOVE NE OF THE AREA  
AND OFFSHORE WITH HEIGHTS GRADUALLY RECOVERING THROUGH THE REMAINDER  
OF THE PERIOD AS UPPER RIDGING BUILDS TO OUR SOUTH. AT THE SFC, THE  
CAD WEDGE IS EXPECTED TO STRENGTHEN OVER THE NEXT SEVERAL HOURS AS  
ITS PARENT HIGH SLIDES FARTHER EAST AND WEAK LOW PRESSURE EVENTUALLY  
LIFTS NORTHWARD JUST OFF THE SE COAST. THE PARENT HIGH WILL BE  
FAIRLY TRANSITORY AND IS EXPECTED TO MOVE EAST OF NOVA SCOTIA  
TOMORROW AFTN, THEREBY ERODING THE CAD LATER TOMORROW AS THE PERIOD  
ENDS AND ALLOWING SOME CLEARING ACROSS MOST OF THE FCST AREA. WITH  
THE CAD IN PLACE, MIN TEMPS EARLY TOMORROW WILL BE COOLER THAN THEY  
HAVE BEEN THE PAST FEW DAYS (ALTHOUGH STILL ABOVE NORMAL), BUT HIGHS  
TOMORROW WILL BE BELOW NORMAL.  
 

 
   
SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/
 
 
AS OF 100 PM SUNDAY: WEAK HIGH PRESSURE WILL REMAIN IN PLACE OVER THE  
REGION INTO WEDNESDAY. A RATHER DEEP UPPER RIDGE WILL BE CENTERED OFF  
THE SOUTHEAST COAST, WHICH WILL ALLOW WEAK MOIST UPGLIDE TO CONTINUE  
OVER THE HIGH; MOSTLY CLOUDY CONDITIONS ARE THUS EXPECTED MONDAY  
NIGHT. THE DISSIPATION OF THOSE CLOUDS TUESDAY, COMBINED WITH THE  
RELATIVELY LARGE THICKNESSES, WILL SUPPORT TEMPS REBOUNDING SEVERAL  
DEGREES ABOVE NORMAL. TUESDAY NIGHT A MOIST WARM FRONT WILL SHIFT  
NORTH FROM THE GULF COAST, AS TC ZETA MOVES NORTHWARD AND A CUTOFF  
UPPER LOW MOVES ACROSS WEST TEXAS. PRECIP MAY SPREAD INTO SOME OF OUR  
AREA AS SOON AS LATE TUESDAY NIGHT; CHANCES INCREASE THRU WEDNESDAY.  
FCST MAX TEMPS FALL BACK SLIGHTLY, MAINLY ON ACCOUNT OF CLOUDIER  
SKIES.  
 

 
   
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
 
 
AS OF 200 PM SUNDAY: ZETA WILL BE CAUGHT BETWEEN THE ATLANTIC RIDGE  
AND THE UPPER LOW, SO IT GENERALLY CAN BE EXPECTED TO CURVE EAST  
AFTER LANDFALL. THE OPERATIONAL GFS AND ITS ENSEMBLE MEMBERS ARE ON  
THE EASTERN SIDE OF THE ENVELOPE, CARRYING THE CIRCULATION CLOSE TO  
THE SOUTHERN APPALACHIANS, WHEREAS THE EC AND ITS ENSEMBLE ARE MORE  
TO THE NORTHWEST AND INLAND. THE CANADIAN IS CLOSER TO THE GFS AT THE  
MOMENT, BUT WITH SIMILAR STORMS EARLIER THIS SEASON IT FLIP-FLOPPED  
BETWEEN THE GFS AND EC CAMPS, SO I WOULDN'T PLACE TOO MANY CHIPS ON  
THAT SO-CALLED CONSENSUS. THE GFS AND CANADIAN TRACKS DO SUGGEST  
STRONGER LOW- TO MID-LEVEL WINDS PASSING OVER OUR AREA. THAT WOULD  
RESULT IN STRONGER UPSLOPE AND FRONTOGENETIC EFFECTS, IN TURN  
RESULTING IN GREATER QPF POTENTIAL. THE RESULTANT 0-1KM AND 0-3KM  
BULK SHEAR WOULD ALSO POINT TO A TC TORNADO THREAT WEDNESDAY NIGHT.  
EVEN IF ZETA STAYS FURTHER WEST, WE MAY NOT BE TOTALLY OUT OF THE  
WOODS FOR SEVERE WX: PRACTICALLY ALL THE AVAILABLE GUIDANCE SHOWS THE  
UPPER LOW TRACKING ACROSS THE TENNESSEE VALLEY LATE THURSDAY, AND  
MORE OR LESS THROUGH OUR CWA THURSDAY NIGHT. A SLIGHTLY UNSTABLE WARM  
SECTOR APPEARS LIKELY TO PRECEDE THE LOW AND ATTENDANT COLD FRONT,  
WITH ENOUGH SHEAR TO PROMPT A HIGH-SHEAR/LOW-CAPE DAMAGING WIND  
THREAT. BOTH SEVERE AND FLOOD THREATS APPEAR MARGINAL AND LOCALIZED  
AT THIS POINT, BUT CONFIDENCE HAS INCREASED TO THE POINT THAT WE WILL  
START TO RAMP UP MESSAGING THE POTENTIAL IMPACTS.  
 
COOLER AIR AND A DRYING TREND SHOULD ARRIVE ON FRIDAY IN THE WAKE OF  
THE FRONT, WITH TEMPS FALLING A LITTLE BELOW NORMAL. MOST LIKELY  
PRECIP WILL END BEFORE ENOUGH COOLING OCCURS FOR A P-TYPE CHANGEOVER;  
THE REMAINING MOISTURE LIKELY WILL BE VERY SHALLOW ANYWAY. SOME FROST  
COULD OCCUR SATURDAY AND SUNDAY MORNINGS, AT LEAST IN THE COOLER  
MOUNTAIN/FOOTHILL LOCATIONS.  
 

 
   
AVIATION /03Z MONDAY THROUGH FRIDAY/
 
 
AT KCLT AND ELSEWHERE: WIDESPREAD IFR CIGS EXPECTED TONIGHT THRU AT  
LEAST THE FIRST HALF OF MONDAY, AS COLD AIR DAMMING PERSISTS. THERE  
ARE PATCHES OF -RA AND DZ AROUND THIS EVENING, AND THAT SHOULD  
GRADUALLY TAPER OFF THRU THE OVERNIGHT. WIND WILL BE IN THE USUAL  
CAD CONFIGURATION, BUT BECOME LIGHTER. THE WEDGE WEAKENS ON MONDAY,  
BUT THE LOW CLOUDS WILL TAKE A WHILE TO IMPROVE, WITH COMPLETE  
SCATTERING OF CIGS IN DOUBT. STILL EXPECT MOST SITES TO REACH VFR BY  
LATE AFTN, WITH KAND BEING THE POSSIBLE EXCEPTION. THE CENTER OF  
HIGH PRESSURE SETTLES OVER THE AREA LATE IN THE DAY, CAUSING WIND TO  
BE MORE VARIABLE OR GO CALM.  
 
OUTLOOK: SOME RETURN OF LOW CLOUDS AND PATCHY FOG EXPECTED AGAIN  
MONDAY NIGHT THRU EARLY TUESDAY, BUT CAD SHOULD COMPLETELY ERODE BY  
TUESDAY AFTN, BRINGING A BRIEF PERIOD OF VFR TO THE AREA. MOISTURE  
QUICKLY SPREADS BACK IN ON WEDNESDAY, AS THE REMNANTS OF ZETA PASS  
BY, WITH ANOTHER ROUND OF WIDESPREAD PRECIP AND RESTRICTIONS LIKELY  
THRU AT LEAST THURSDAY. DRY AIR BEGINS TO FILTER IN BEHIND ZETA ON  
FRIDAY.  
 
CONFIDENCE TABLE...  
 
02-08Z 08-14Z 14-20Z 20-00Z  
KCLT MED 69% MED 61% HIGH 91% HIGH 81%  
KGSP MED 64% MED 66% HIGH 85% HIGH 86%  
KAVL HIGH 91% HIGH 97% LOW 59% HIGH 84%  
KHKY MED 66% MED 77% HIGH 85% HIGH 89%  
KGMU MED 69% MED 62% HIGH 84% HIGH 85%  
KAND MED 78% HIGH 88% HIGH 90% HIGH 82%  
 
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING  
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY  
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES 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...ARK/JPT  
SHORT TERM...WIMBERLEY  
LONG TERM...WIMBERLEY  
AVIATION...ARK  
 
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