501  
FXUS62 KGSP 231916  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
216 PM EST FRI FEB 23 2018  
   
SYNOPSIS
 
 
VERY WARM CONDITIONS WILL CONTINUE THROUGH MOST OF THE WEEKEND. A  
COLD FRONT WILL SLOWLY CROSS THE AREA SUNDAY INTO MONDAY, BRINGING  
GREATER CHANCES OF SHOWERS AND A FEW THUNDERSTORMS WITH IT. DRIER  
AND COOLER HIGH PRESSURE WILL SETTLE OVER THE REGION TUESDAY THROUGH  
WEDNESDAY.  
 

 
   
NEAR TERM /THROUGH SATURDAY/
 
 
AS OF 200 PM EST FRIDAY: NOTHING LIKE A NICE SPRING DAY...IN  
FEBRUARY! MODEST HEATING THIS AFTERNOON IS UNDERWAY WITH CLT/GSP  
ALREADY TYING RECORDS, LIKELY TO BREAK THEM. AS FOR KAVL, STILL  
A FEW DEGREES SHORT, BUT STILL TIME FOR WARMING TO OVERCOME THOSE  
RECORDS AS WELL. ANYWAYS, OVERALL THE PATTERN HASN'T CHANGED ALL  
THAT MUCH WITH A LARGE UPPER ANTICYCLONE CENTERED OVER THE WESTERN  
ATL KEEPING A STALLED FRONTAL AXIS TO THE WEST. WITH THAT, SAID  
ABOVE NORMAL TEMPERATURES WILL PREVAIL TODAY/TONIGHT, LESS LIKELY  
TOMORROW AS THE RECORDS ARE A FEW DEGREES WARMER. OTHERWISE,  
EXPECTING PARTLY CLOUDY SKIES THIS AFTERNOON AS AMPLE LLV MOISTURE  
AND HEATING COMBINE TO YIELD CU, WITH SOME SCT'ING FAVORED INTO  
THE EVENING/OVERNIGHT. ANOTHER ROUND OF LOWER STRATUS AND POSSIBLY  
FOG IS EXPECTED AGAIN TOMORROW MORNING GIVEN A PERSISTENCE FCST,  
THEREFORE SKY COVER IS FAVORED TO INCREASE TOWARD SUNRISE SATURDAY,  
EVENTUALLY SCT'ING OUT ONCE AGAIN INTO THE AFTERNOON YIELDING  
ABOVE NORMAL TEMPERATURES. AS FOR PRECIPITATION THIS FCST CYCLE,  
DID CONTINUE WITH INCREASING SLIGHT/CHANCE POPS ALONG THE HIGH  
TERRAIN THIS EVENING/OVERNIGHT AS GUIDANCE FAVORS A WAVE OF ENERGY  
SLIDING ALONG THE STALLED FRONT, ALBEIT WITH SOME SLIGHT TIMING  
DIFFERENCES. BEYOND THAT, HEATING INTO THE AFTERNOON HOURS ON  
SATURDAY COULD YIELD ENOUGH FREE SBCAPE ALONG THE TN LINE GIVEN  
FURTHEST DISTANCE FROM THE AFOREMENTIONED ATL RIDGE, THUS ISO/SCT  
TSRA CANNOT BE RULED OUT.  
 

 
   
SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/
 
 
AS OF 100 PM EST FRIDAY: AT THE START OF THE SHORT TERM PERIOD  
SATURDAY EVENING, THE STRONG UPPER RIDGE WILL STILL BE IN PLACE OVER  
THE WESTERN ATLANTIC, WITH A DEEP UPPER TROUGH BUILDING OVER THE  
ROCKIES. THE INITIAL SHORTWAVE EMBEDDED WITHIN THE TROUGH WILL BE  
APPROACHING THE MS VALLEY AT THE START OF THE PERIOD, WITH A  
SECONDARY SHORTWAVE DIVING INTO THE NORTHERN ROCKIES. SURFACE HIGHS  
IN EASTERN CANADA AND OVER THE WESTERN ATLANTIC WILL BE SEPARATED BY  
THE QUASISTATIONARY WARM FRONT, WHILE A COLD FRONT WILL DRAG ACROSS  
THE LOWER MS VALLEY AS THE SURFACE LOW OVER THE MID MS VALLEY  
CONTINUES TO OCCLUDE. SHOWERY ACTIVITY CAN BE EXPECTED SATURDAY  
NIGHT ESPECIALLY ACROSS TYPICAL UPSLOPE AREAS AS LOW LEVEL WAA  
CONTINUES. THE COLD FRONT WILL PUSH EAST ON SUNDAY, LOSING SOME OF  
ITS OOMPH, AS THE UPPER RIDGE IS FORCED SOUTH AND WILL BEGIN TO  
RETROGRADE INTO THE GULF AND WESTERN CARIBBEAN. WITH THE AREA  
REMAINING IN THE WARM SECTOR, THE SYNOPTIC LIFT (THOUGH WEAKENING)  
ADDED BY THE FRONT WILL LIKELY BE ENOUGH FOR AT LEAST A FEW  
THUNDERSTORMS TO DEVELOP ACROSS THE PIEDMONT AND MAYBE FOOTHILLS,  
WITH BETTER CHANCES ACROSS THE UPSTATE AND NE GA. SBCAPE IS NOT  
PARTICULARLY IMPRESSIVE, REMAINING BELOW 500 J/KG, WITH DEEP-LAYER  
SHEAR INCREASING (50-60KT) AS THE FRONT APPROACHES. CERTAINLY SOME  
MINIMAL CONCERN FOR HSLC CONVECTION SUNDAY AFTERNOON, SO WILL  
CONTINUE TO WATCH FORECAST EVOLUTION. EXPECT ONE MORE DAY OF  
AFTERNOON HIGHS 15+ DEGREES ABOVE SEASONAL NORMALS.  
 
STILL SEEING SOME DIFFERENCES IN HOW THE ECMWF AND GFS ARE HANDLING  
THE SECONDARY SURGE OF MOISTURE ON MONDAY, BUT THE 12Z ECMWF HAS  
COME IN SLIGHTLY FARTHER SE WITH THE QPF AXIS, CLOSER TO WHAT THE  
GFS HAS BEEN INDICATING. BASICALLY THAT SECONDARY SHORTWAVE WILL  
PUSH INTO THE PLAINS AND PULL ANOTHER SLUG OF MOISTURE OUT OF THE  
GULF AS THE UPPER WAVE BEGINS TO DAMP. THE COLD FRONT WILL STALL  
ACROSS THE AREA AND MAY BRIEFLY LIFT BACK NORTH WITH THE SURGE OF  
MOISTURE, BUT IT'S STARTING TO LOOK LIKE THE MORE SIGNIFICANT  
RAINFALL IS LESS LIKELY (AND EVEN IF SO, IT WOULD BE FARTHER S) WITH  
THE SURFACE LOW WORKING IT'S WAY MORE ACROSS THE FALL LINE RATHER  
THAN I-85. SHOULD SEE HIGHS ON MONDAY A GOOD 5-8 DEGREES COOLER (BUT  
STILL 10 OR SO DEGREES ABOVE NORMAL) THAN ON SUNDAY, BUT THIS WILL  
BE HIGHLY DEPENDENT ON HOW QUICKLY THE FRONT MOVES THROUGH. ALL POPS  
SHOULD BE PRETTY MUCH OUT OF THE AREA BY 00Z TUESDAY.  
 

 
   
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
 
 
AS OF 130 PM EST FRIDAY: DRY HIGH PRESSURE WILL BUILD IN ON TUESDAY  
IN THE WAKE OF THE FRONTAL PASSAGE, WITH HIGHS STILL ABOVE SEASONAL  
NORMALS BUT AT LEAST TRENDING IN THE RIGHT DIRECTION. A BROAD LOW-  
AMPLITUDE RIDGE WILL BUILD ACROSS THE SOUTHEAST, WHILE A CUTOFF  
MIDLEVEL LOW FORMS OVER CA. SPLIT FLOW PATTERN WILL COME TOGETHER  
OVER THE NORTHERN PLAINS, AND AS THE CUTOFF LOW SLOWLY MOVES EAST,  
SURFACE LOW FORMATION OVER THE CENTRAL PLAINS WILL BEGIN TO DRAG  
ANOTHER SLUG OF MOISTURE OUT OF THE GULF AND INTO THE LOWER MS  
VALLEY. OUR SURFACE HIGH WILL MOVE OFF THE NC/VA COASTS BY TUESDAY  
NIGHT, WITH THE MOISTURE ADVECTION REALLY PICKING UP SHORTLY  
THEREAFTER. EXPECT SOME SHOWERY ACTIVITY TO BEGIN TUESDAY NIGHT  
ACROSS THE TYPICAL UPSLOPE AREAS, SPREADING EAST AND NORTH WEDNESDAY  
AS THE WARM FRONT SURGES; HOWEVER, INDICATIONS ARE THAT THE  
PRECIPITATION INTO THE DRY SURFACE LAYER MAY RESULT IN SOME INSITU  
DAMMING WEDNESDAY, WHICH WILL STALL THE WARM FRONTAL SURGE INTO THE  
CAROLINAS AND KEEP HIGHS WEDNESDAY PRETTY CLOSE TO SEASONAL NORMALS.  
GFS IS QUITE A BIT STRONGER WITH THE DEVELOPMENT OF THE SURFACE LOW,  
AND ALSO A BIT FASTER, BUT ENOUGH SIMILARITIES IN THE GENERAL TREND  
TO LEND SOME CONFIDENCE TO PRECIP PUSHING OUT ON THURSDAY NIGHT.  
DAMMING WILL ERODE (PER CURRENT GUIDANCE) ON THURSDAY LEAVING OUR  
AREA AGAIN IN THE WARM SECTOR AND HIGHS THU ABOUT 10 DEGREES ABOVE  
NORMAL. LINGERING NW FLOW SHOWERS CAN BE EXPECTED ACROSS THE  
MOUNTAINS WITH THE UPPER SYSTEM, AND BEHIND THE FRONT (WHENEVER IT  
ENDS UP PASSING) WE MIGHT ACTUALLY GET SOME CAA TO WORK WITH, BUT  
TOO FAR OUT TO GET INTO DETAILS AT THIS TIME.  
 

 
   
AVIATION /19Z FRIDAY THROUGH WEDNESDAY/
 
 
AT KCLT AND ELSEWHERE: A MOIST PATTERN CONTINUES ACROSS THE REGION  
THIS FCST CYCLE AS A STALLED FRONT REMAINS WESTWARD KEEPING THE  
FCST AREA IN THE WARM SECTOR. WITH THAT, MOIST SWLY/SLY FLOW  
WILL PREVAIL THROUGH THE PERIOD WITH SAID MOISTURE SUPPORTIVE OF  
VARYING CIG HEIGHTS. WITH THAT, INITIALIZED MVFR AT KAND/KHKY  
GIVEN LINGERING STRATUS, WHILE LEADING OFF WITH LOW VFR AT ALL  
OTHER SITES. ALL SITES SHOULD GO VFR WITHIN THE NEXT HOUR/TWO.  
OTHERWISE, BRIEF RELIEF FROM THE LOW CIGS/VISB INTO THE OVERNIGHT  
BEFORE ANOTHER ROUND OF SAID RESTRICTIONS RETURNS AHEAD OF  
SUNRISE SATURDAY. MEANWHILE, A WEAK WAVE LOOKS TO TRAVERSE  
THE AFOREMENTIONED FRONTAL BOUNDARY, SLIDING INTO THE TN VALLEY  
OVERNIGHT. THUS, CANNOT RULE OUT SOME STRAY SHOWERS ACROSS THE  
WESTERN TIER OF THE FCST AREA TO AFFECT ALL SITES ASIDE FOR KCLT,  
THEREFORE PROB30S WERE INCLUDED. CONDITIONS WILL IMPROVE FROM  
MVFR/IFR AND POSSIBLY LIFR CIGS AND VISB INTO THE LATE MORNING  
HOURS AS HAS HAPPENED TODAY, THUS EACH SITE WILL EXPERIENCE  
IMPROVEMENT LATE. AS STATED, WINDS WILL REMAIN SWLY/SLY THROUGH THE  
PERIOD WITH SOME LOW END GUSTING POSSIBLE AT KAVL THIS AFTERNOON.  
OTHERWISE LOOK FOR WINDS IN THE 6-10KTS RANGE AT ALL SITES THIS  
AFTERNOON, WEAKENING OVERNIGHT WITH LOSS OF MIXING, INCREASING  
AGAIN ON SATURDAY.  
 
OUTLOOK: MOIST CONDITIONS WILL KEEP CHANCES FOR RESTRICTIONS  
ELEVATED THROUGH THE PERIOD, WITH THE BEST CHANCES FOR LOW CIGS/VISB  
TO OCCUR EACH MORNING. PRECIPITATION CHANCES ARE ALSO SLIGHTLY  
ELEVATED, MAINLY ACROSS THE HIGH TERRAIN.  
 
CONFIDENCE TABLE...  
 
19-01Z 01-07Z 07-13Z 13-18Z  
KCLT HIGH 100% HIGH 100% HIGH 92% HIGH 83%  
KGSP HIGH 98% HIGH 100% HIGH 89% HIGH 89%  
KAVL HIGH 100% HIGH 98% HIGH 82% HIGH 86%  
KHKY HIGH 92% HIGH 100% HIGH 85% HIGH 89%  
KGMU HIGH 100% HIGH 100% HIGH 86% HIGH 91%  
KAND HIGH 100% HIGH 100% HIGH 87% HIGH 84%  
 
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  
 

 
   
CLIMATE
 
 
RECORDS FOR 02-23  
 
MAX TEMPERATURE MIN TEMPERATURE  
STATION HIGH LOW HIGH LOW  
------- ---------- ---------- ---------- ----------  
KAVL 76 1982 29 1989 54 1922 10 1939  
KCLT 76 2012 29 1901 56 1944 19 2009  
1980 1978  
1962 1963  
KGSP 76 2012 36 1966 57 1922 15 1963  
1996 1939  
1980  
 
RECORDS FOR 02-24  
 
MAX TEMPERATURE MIN TEMPERATURE  
STATION HIGH LOW HIGH LOW  
------- ---------- ---------- ---------- ----------  
KAVL 77 1930 26 1947 50 1985 6 1967  
1979  
KCLT 80 1982 26 1889 56 1992 16 1967  
1930  
KGSP 79 1982 33 1901 57 1909 15 1967  
1901  
 
RECORDS FOR 02-25  
 
MAX TEMPERATURE MIN TEMPERATURE  
STATION HIGH LOW HIGH LOW  
------- ---------- ---------- ---------- ----------  
KAVL 78 1930 17 1967 51 1985 -2 1967  
KCLT 82 1930 27 1967 58 1890 7 1967  
1914  
KGSP 79 1930 30 1967 57 1985 8 1967  
 

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

 
 

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