446  
FXUS62 KGSP 240658  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
258 AM EDT TUE OCT 24 2017  
   
SYNOPSIS
 
 
DRIER AND COOLER AIR WILL SWEEP INTO THE REGION TODAY LEADING TO  
POSSIBLE FROSTY CONDITIONS WEDNESDAY AND THURSDAY MORNINGS. DRY  
CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE REMAINDER OF THE WORK  
WEEK BEFORE ANOTHER FRONT MOVES IN NEXT WEEKEND.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 245 AM EDT: LOW STRATUS AND FOG WILL BE THE PRIMARY NEAR-TERM  
ISSUE THIS MORNING, PRIMARILY ALONG THE INTERSTATE 77 CORRIDOR WHERE  
BOUNDARY LAYER DRYING ON WESTERLY FLOW HAS BEEN DELAYED.  
 
OTHERWISE, A WEAK SURFACE TROUGH AXIS WILL LINGER ALONG THE BLUE  
RIDGE IN WESTERLY FLOW TODAY. MEANWHILE, THE DEEPENING UPSTREAM  
TROUGH AXIS WILL MOVE EAST TOWARD THE APPALACHIANS, WITH A BROAD  
AREA OF MID-LEVEL DPVA AND STEEPENING LAPSE RATES REACHING THE NC  
MOUNTAINS THIS AFTERNOON. A FEW SHOWERS COULD RESULT OVER THE HIGH  
TERRAIN, BUT PROFILES REMAIN RELATIVELY DRY SO WILL LIMIT ANY LOW  
POP MENTION TO JUST THE WESTERN MOUNTAINS AND HIGHER RIDGES.  
 
THE TROUGH AXIS WILL BRING A REINFORCING SHOT OF COOLER AIR TO THE  
REGION LATE TODAY THROUGH TONIGHT. SHALLOW NORTHWEST FLOW MOISTURE  
WILL ALSO ARRIVE IN THE WESTERN MOUNTAINS LATE TONIGHT AND A FEW  
HIGH ELEVATION SNOW SHOWERS COULD MIX IN LATE, BUT WITH NO  
ACCUMULATIONS EXPECTED. THE COLDER TEMPERATURES WILL PERMIT MANY  
MOUNTAIN LOCATIONS TO EXPERIENCE NEAR FREEZING MINIMUM TEMPERATURES.  
FROST ISSUES APPEAR LIMITED BY THE CONTINUED MIXING AND POSSIBLY  
INCREASING CLOUDS LATE. STILL, FREEZE WARNINGS WILL LIKELY BE NEEDED  
ACROSS THE NORTHERN MOUNTAINS AND ALSO HAYWOOD COUNTY, AND  
CONDITIONS WILL NEED TO BE MONITORED FOR POSSIBLE EXPANSION OR NEW  
FROST ADVISORIES LATER TODAY FOR TONIGHT.  
 

 
   
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
 
 
AS OF 200 AM EDT TUESDAY: THE SHORT TERM FCST PERIOD KICKS OFF ON  
WEDNESDAY MORNING AMIDST DEEP FULL LATITUDE H5 TROFFING ACROSS THE  
EASTERN CONUS, WHILE RIDGING BUILDS OVER THE DESERT SOUTHWEST. AT  
THE SURFACE, BROAD COOL/DRY HIGH PRESSURE CENTERED WESTWARD ACROSS  
CENTRAL TX WILL EXTEND WELL TO EAST INTO THE SOUTHERN APPALACHIAN  
REGION AT FCST INITIALIZATION, WITH IT'S CENTER MOVING EASTWARD OVER  
THE CENTRAL GOM BY THURSDAY MORNING. CLOSER TO HOME THIS PATTERN  
WILL YIELD DRY WEATHER AND BELOW NORMAL TEMPERATURES. WITH THAT,  
GUIDANCE DOES FAVOR POSSIBLE FREEZE CONDITIONS AT FCST ONSET WITH  
FROST POSSIBLY HINDERED TO SOME DEGREE BY LIGHT WINDS. HOWEVER ON  
THURSDAY MORNING THE PG WILL BE RELAXED A BIT YIELDING IMPROVED  
FROST CONDITIONS ACROSS THE LOW TERRAIN, AS WELL AS FREEZING  
TEMPERATURES ACROSS THE NORTHERN MTNS AND IN THE CENTRAL/SOUTHERN  
MTN VALLEYS. ON TOP OF THAT, GUIDANCE CONTINUES TO FAVOR SOME  
REINFORCING MOISTURE THANKS TO A PASSING SHORTWAVE AMONG THE MEAN  
FLOW ALOFT, WHICH LOOKS TO IMPACT THE WESTERN SLOPES OF THE APPS  
INTO THURSDAY MORNING. PROFILES AT THAT TIME WILL SUPPORT WINTRY  
PRECIP IN THE FORM OF SNOW SHOWERS, THUS SUCH WILL BE INCLUDED IN  
THE FCST AT THE HIGHER PEAKS WITH NO ACCUMULATION EXPECTED. BEYOND  
THAT THE PATTERN BEGINS TO MODIFY AS THE UPPER TROF EJECTS OVER THE  
WESTERN ATL AND SHORTWAVE H5 RIDGING MOVES ACROSS THE SOUTHEAST  
STATES. IN RESPONSE, THE SURFACE ANTICYCLONE WILL MOVE ONSHORE  
THURSDAY AFTERNOON AND CONTINUE MOVING TO THE NORTHEAST ALONG THE  
ATL SHORELINE THROUGH THE REMAINDER OF THE PERIOD. THIS PATTERN  
WILL FAVOR SLY BACKED SURFACE FLOW AND THUS A WEAK WAA REGIME  
LEADING TO IMPROVED TEMPERATURES/DEWPOINTS. THEREFORE THE FCST WILL  
FEATURE TEMPERATURES NEARLY 8-10 DEGREES BELOW NORMAL ON WEDNESDAY  
AS WELL AS THURSDAY MORNING, WARMING A FEW DEGREES FOR THURSDAY  
AFTERNOON YET STILL NEARLY A CAT/TWO BELOW NORMAL.  
 

 
   
LONG TERM /FRIDAY THROUGH MONDAY/
 
 
AS OF 230 AM EDT TUESDAY: THE MEDIUM RANGE FCST PERIOD PICKS UP ON  
FRIDAY MORNING AMIDST AN INCREASINGLY AMPLIFIED UPPER PATTERN  
HIGHLIGHTED BY WEAK RIDGING ALONG THE EAST COAST, WHILE A SHARP FULL  
LATITUDE TROF CONSUMES THE ROCKIES/PLAINS WITH A REGION OF SURFACE  
CYCLOGENESIS OVER THE UPPER MIDWEST DRIVING A COLD FRONT INTO THE MS  
RIVER VALLEY. PATTERN EVOLUTION THROUGH THE PERIOD WILL FEATURE  
CONTINUED WAA ACROSS THE SOUTHEAST INTO SATURDAY AS THE  
AFOREMENTIONED COLD FRONT APPROACHES OUT OF THE TN VALLEY BY  
MID/LATE DAY. AHEAD OF THE FRONT, MOISTURE ADVECTION WILL INCREASE  
WARRANTING ELEVATED POPS IN THE UPSLOPE FAVORED REGIONS FIRST THEN  
SPREADING OUT ACROSS THE CWFA OVERNIGHT INTO SUNDAY MORNING. BY  
THAT POINT GUIDANCE SEEMS TO BE IN BETTER AGREEMENT THAN PREVIOUS  
RUNS IN THAT FRONT WILL BE MOVING INTO WESTERN NC, POSSIBLY WITH A  
LINE OF CONVECTION TO ACCOMPANY. THE FRONT WILL PUSH ACROSS  
NORTHEAST GA AND THE WESTERN CAROLINAS ON SUNDAY WARRANTING HEALTHY  
POPS REGIONWIDE, EVENTUALLY MOVING OUT OVERNIGHT INTO MONDAY  
MORNING. AT THAT POINT THERMAL PROFILES WILL BE COOLING RAPIDLY  
GIVEN THE STRENGTH OF POST FRONTAL CAA THEREFORE LINGERING MOISTURE  
ACROSS THE HIGH TERRAIN COULD YIELD THE FIRST MEASURABLE NWFS EVENT  
JUST IN TIME FOR OUR SNOWFALL SEASON TO BEGIN AT THE FIRST OF  
NOVEMBER. TEMPERATURES THROUGH THE MEDIUM RANGE WILL INITIALIZE  
WARM AT NEAR NORMAL LEVELS, COOLING A BIT SATURDAY/SUNDAY GIVEN  
INCREASED COVERAGE OF CLOUDS/PRECIP, THEN FALLING TO BELOW NORMAL  
INTO MONDAY.  
 

 
   
AVIATION /07Z TUESDAY THROUGH SATURDAY/
 
 
AT HHKY: COMMUNICATIONS TO THE KHKY ASOS HAVE BEEN LOST DUE TO THE  
MONDAY SEVERE STORMS. AMD NOT SKED WILL THUS BE FEATURED THERE UNTIL  
FURTHER NOTICE. LOW CLOUDS AND FOG COULD APPEAR AT TIMES THROUGH  
DAYBREAK GIVEN THE ABUNDANT GROUND MOISTURE ALONG WITH CLEAR SKIES  
AND SLACKENING WINDS OVERNIGHT. SOME DRYING IS EXPECTED FROM THE  
WEST SO WILL KEEP CLOUD BASES SCATTERED FOR NOW, WITH FOG LIMITED TO  
MVFR. HOWEVER, IFR TO LIFR CONDITIONS ARE CERTAINLY POSSIBLE. EXPECT  
AN UPTICK IN WSW FLOW TODAY WITH MAINLY HIGH CLOUDS AND THEN WINDS  
ADJUSTING MORE WNW TONIGHT.  
 
AT KCLT AND ELSEWHERE: SKIES HAVE CLEARED, OR ARE CLEARING, AT THE  
TAF SITES. GROUND MOISTURE WILL RAISE THE POTENTIAL FOR SOME LOW  
CLOUDS AND FOG THROUGH DAYBREAK, BUT CHANCES APPEAR THE BEST AROUND  
KCLT WHERE DRYING FROM THE WEST IS DELAYED. WILL KEEP LOW CLOUD  
BASES THERE SCATTERED FOR NOW. OTHERWISE, EXPECT LIGHT W TO SW FLOW,  
NW AT KAVL, BECOMING SLIGHTLY GUSTY THROUGH THE DAY WITH MIXING. VFR  
CONDITIONS ARE EXPECTED THROUGHOUT DESPITE THE APPROACH OF A ROBUST  
TROUGH FROM THE WEST TONIGHT. WINDS MAY TOGGLE MORE WNW TONIGHT.  
 
OUTLOOK: DRIER AND COOLER CONDITIONS WILL CONTINUE THROUGH  
THURSDAY. DEEP MOISTURE WILL RETURN AHEAD OF ANOTHER COLD FRONT OVER  
THE WEEKEND.  
 
CONFIDENCE TABLE...  
 
07-13Z 13-19Z 19-01Z 01-06Z  
KCLT MED 73% HIGH 91% HIGH 100% HIGH 100%  
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KAVL HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KHKY LOW 43% HIGH 96% HIGH 100% HIGH 100%  
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KAND HIGH 100% 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...FREEZE WARNING FROM 1 AM TO 9 AM EDT WEDNESDAY FOR NCZ033-049-  
050-052.  
SC...NONE.  
 

 
 

 
SYNOPSIS...CDG  
NEAR TERM...HG  
SHORT TERM...CDG  
LONG TERM...CDG  
AVIATION...HG  
 
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