602  
FXUS62 KGSP 181451  
AFDGSP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC  
951 AM EST WED JAN 18 2017  
   
SYNOPSIS
 
 
A WEAK COLD FRONT WILL CROSS THE CAROLINAS FROM THE WEST TODAY  
BRINGING INCREASED CHANCES FOR PRECIPITATION. A WARM FRONT WILL LIFT  
NORTHWARD OVER THE REGION ON THURSDAY AND FRIDAY, BRINGING MORE RAIN  
TO THE SOUTHEAST. A MORE SIGNIFICANT LOW PRESSURE SYSTEM IS EXPECTED  
TO DEVELOP OVER THE REGION ON SUNDAY, BRINGING MORE UNSETTLED  
WEATHER TO THE AREA.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 1000 AM EST WEDNESDAY: COLD FRONT IS JUST EAST OF THE BLUE  
RIDGE AT UPDATE TIME, WITH MOSTLY CLEAR SKIES. JUST USING GSP AS AN  
EXAMPLE, TEMPERATURE HERE IS ALREADY 67 (STRIKE THAT, JUST BUMPED UP  
TO 68 RIGHT BEFORE ISSUING THE UPDATE AFD) DEGREES. WHAT MEAGER CAA  
THERE IS WITH THE FRONT WILL COMPETE WITH THE UPPER RIDGE,  
DOWNSLOPING AND LOTS OF SUNSHINE. CURRENT HIGH TEMPERATURES ARE  
ABOVE PRETTY MUCH ALL GUIDANCE EXCEPT THE RAP WHICH IS ABOUT THE  
SAME. MANUALLY BUMPED UP TEMPERATURES A LITTLE ACROSS THE UPSTATE  
BUT WILL KEEP A CLOSE EYE ON IT IN CASE ADDITIONAL ADJUSTMENTS ARE  
NECESSARY. LOWERED POPS AND SKY COVER THROUGH THE DAY TO MATCH  
CURRENT RADAR/SATELLITE TRENDS. OTHER BIG NEWS IS THE WINDS AT THE  
HIGHEST ELEVATIONS OF THE NORTHERN NC MOUNTAINS - GRANDFATHER HAS  
BEEN GUSTING >80MPH SINCE 8AM (84MPH NOW). MT. MITCHELL GUSTING TO  
56MPH. THESE WINDS AREN'T GETTING LOW ENOUGH TO CONSIDER ISSUING ANY  
PRODUCTS BUT WILL ALSO BE MONITORING THEM.  
 
OTHERWISE, A POTENT SHORT WAVE TROUGH, SHOWN RATHER PROMINENTLY IN  
THE LATEST WATER VAPOR IMAGERY APPROACHING THE CENTRAL APPALACHIANS  
WILL CONTINUE TO DIG E/SE THROUGH THE MORNING, AND SHOULD EXIT THE  
MID-ATLANTIC COAST THIS AFTERNOON. SURFACE HIGH PRESSURE SPREADING  
INTO THE TN VALLEY IN THE WAKE OF THIS FEATURE WILL PUSH THE COLD  
FRONT SOUTH OF THE AREA BY THE END OF THE DAY. HOWEVER, WITH THE  
FRONT TAKING ON AN INCREASINGLY ZONAL ORIENTATION, AND PREDOMINANT  
W/NW LOW LEVEL FLOW EXPECTED ACROSS THE REGION, THE FRONTAL  
CIRCULATION WILL CONTINUE TO WEAKEN, AND NOTHING MORE THAN TOKEN  
SMALL CHANCE POPS (MAINLY ACROSS THE MTNS AND SOUTHERN PIEDMONT)  
APPEAR WARRANTED THIS MORNING.  
 
TODAY'S MAIN HIGHLIGHT WILL BE WARM TEMPS EAST OF THE MTNS,  
ESP ALONG AND SOUTH OF THE I-85 CORRIDOR, WHERE THE FRONT IS  
UNLIKELY TO COMPLETELY CLEAR THE AREA UNTIL THIS AFTERNOON, WHILE  
STRONG COMPRESSIONAL/DOWNSLOPE WARMING WILL OFFSET THE RELATIVELY  
WEAK COLD AIR ADVECTION IN AREAS THAT DO SEE FROPA EARLIER IN THE  
DAY. MAXES ARE EXPECTED TO RANGE FROM 10-15 DEGREES ABOVE CLIMO  
(I.E., MID 60S) ACROSS THE NORTHERN PIEDMONT AND FOOTHILLS, AS WELL  
AS THE MTN VALLEYS, TO AS MUCH AS 20 DEGREES ABOVE NORMAL ACROSS THE  
SC FOOTHILLS AND PIEDMONT, WHERE TEMPS IN THE 70S APPEAR TO BE A  
GOOD BET. RECORD HIGHS WILL BE FLIRTED WITH AT KGSP AND KCLT.  
 
THE FRONT SHOULD BE SOUTH OF THE FORECAST AREA BY THIS EVENING, AND  
LOWERING THICKNESS VALUES, WHILE A WEAKENING GRADIENT AND INITIALLY  
CLEAR SKIES WILL YIELD DECENT RADIATIONAL COOLING CONDITIONS, AT  
LEAST PRIOR TO THE ANTICIPATED ARRIVAL OF HIGH CLOUDS TOWARDS  
DAYBREAK. THIS WILL ALLOW FOR MIN TEMPS THAT WILL BE AS MUCH AS 20  
DEGREES COOLER THAN WEDNESDAY MORNING'S READINGS, BUT STILL 5-10  
DEGREES ABOVE CLIMO.  
 

 
   
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
 
 
AS OF 300 AM EST WEDNESDAY...THE SHORT RANGE BEGINS WITH AN H5 RIDGE  
AXIS OVERHEAD AND A RELATIVELY WARM SFC HIGH ENCOMPASSING THE  
CAROLINAS. THIS RIDGE AND HIGH WILL MIGRATE TO THE ATL COAST THRU  
THE DAY WHILE MOISTURE FLUX AND LAYERED CLOUDS INCREASE FROM THE  
WEST. AN OCCLUDED FRONTAL ZONE WILL WORK IT/S WAY INTO THE CWFA  
OVERNIGHT BRINGING -SHRA TO MOST AREAS BY DAYBREAK. MEANWHILE...THE  
PRECIP WILL INTERACT WITH THE PREVAILING SFC RIDGING AND PRODUCE A  
HYBRID-WEDGE WITH A DISTINCT BNDRY GENERALLY BISECTING THE I-85  
CORRIDOR.  
 
MODEL SOUNDINGS SHOW HIGH 0-3 KM HELICITY ALONG THIS ZONE...
ARND 300  
M2/S2...AND A DEVELOPING STRONG H85 JET ALIGNED WITHIN WAA BTW 06Z  
AND 15Z. INSTABILITY SHUD REMAIN QUITE LOW WITH THE NAM ONLY SHOWING  
ABOUT 150 J/KG PEAKING ARND 12Z AND THE GFS REMAINING STABLE. ALSO  
THERE WILL BE A NICE SLUG OF H7-H5 DPVA CROSSING DURING THIS  
TIME-FRAME. SO...THERE WILL BE SIGFNT ELEMENTS IN PLAY FOR STRONG  
SEMI-ORGANIZED AND POSSIBLY ROTATING LINE SEGMENTS THROUGH THE  
MORNING HRS ALONG AND SOUTH OF I-85. TOO MUCH UNCERTAINTY IS HAD  
WITH INSTABILITY FOR INCLUSION OF THUNDER IN THE GRIDS AND THE TIME  
OF DAY IS A NEG FACTOR FOR A MENTION IN TODAY/S HWO...BUT THIS  
SITUATION WILL BE WATCHED CLOSELY OVER THE NEXT COUPLE DAYS. MAX  
TEMPS WLLL GENERALLY REMAIN ARND 10 DEGREES ABOVE NORMAL EVEN WITH  
INCREASING CLOUDS AS LLVL WAA MIXES INTO THE BNDRY LAYER.  
 

 
   
LONG TERM /SATURDAY THROUGH TUESDAY/
 
 
AS OF 350 AM EST WEDNESDAY: THE EXT RANGE REMAINS PRETTY INTERESTING  
WITH THE EXPECTED SYNOPTIC PATTERN. ON SAT...THE RECENTLY DOMINANT  
SUBTROP HIGH WILL GET NUDGED EAST AS FRI/S ELONGATED H5 TROF SWINGS  
TOWARD THE MIDWEST AND INCREASES THE OVERALL BROADNESS OF THE WRN  
CONUS TROF. MEANWHILE...STRONG ENERGY ORIGINATING FROM THE PAC NW  
WILL HAVE MADE IT ACROSS THE SRN ROCKIES AND WILL INSTIGATE QUICK  
CYCLOGENESIS ACROSS THE TX/OK PANHANDLE REGION. THIS SYSTEM WILL  
BECOME OCCLUDED QUICKLY AS WELL...AND WILL SERVE TO DEEPEN AND  
STRENGTHEN THE OVERALL PARENT L/W TROF AS IT MOVES INTO THE DEEP  
SOUTH THROUGH SUN.  
 
WITH THE SUBTROP RIDGE BREAKING DOWN SAT...A LLVL BNDRY ACROSS THE  
NRN GOM WILL MOISTEN UP SIGFNT/LY AND BEGIN TO INTERACT WITH THE  
INCOMING OCCLUDED SYSTEM WHILE ADVANCING TOWARD THE CWFA AS A WARM  
FRONT. NOT EXPECTING MUCH PRECIP DURING THE DAY SAT WITH GENERALLY  
MECH LIFT -SHRA ACROSS THE MTN ZONES SPREADING EAST...BUT BY SAT  
NIGHT ULVL DIFL INCREASES ALONG WITH STEEPENING MLVL LAPSE RATES.  
GOOD MOIST GOM FLUX WILL ENSUE AS WELL INCREASING THE MODERATE TO  
HEAVY RAIN POTENTIAL...WITH GOOD RAINFALL AMOUNTS LIKELY CONTINUING  
THRU SUN NIGHT AS THE OCCLUDED FRONT CROSSES THE REGION. THE  
NORMALLY STINGY WITH INSTABILITY GFS HAS INCREASING SBCAPE VALUES  
ACROSS THE SRN HALF OF THE CWFA BEGINNING AFT MIDNIGHT  
SAT...REACHING NEAR 750 J/KG BY MID-DAY SUN. SOUNDINGS ARE ALSO  
SHOWING HIGH END AMOUNTS OF LLVL HELICITY AS THE WARM FRONT BNDRY  
MEANDERS OVER THE AREA. THUS...THE PERIOD SAT NIGHT THRU SUN NIGHT  
WILL HAVE THE POTENTIAL FOR CONVECTIVE HEAVY PRECIP ALONG WITH  
STG/SVR TSTMS. WILL KEEP THE HAZARD WORDAGE SIMILAR IN THE HWO.  
 
ON MON...THE UPPER LOW CROSSES THE AREA AND WILL MAINTAIN ISOL/SCT  
-SHRA/TSTMS WITH RATHER LIGHT ADDITIONAL RAIN AMOUNTS EXPECTED. SOME  
BELOW FREEZING AIR DOES MAKE IT TO THE HIGHER MTN PEAKS MON NIGHT  
AND ENOUGH LIFT AND MOISTURE SHUD BE AVAILABLE FOR PERIODS OF LIGHT  
SNOW WITH LITTLE OR NO ACCUMS. A RELATIVELY WARM SRN STREAM HIGH  
BUILDS IN TUES AND GENERALLY MAX TEMPS OVER THE EXT RANGE WILL  
REMAIN ARND 10 DEGREES ABOVE NORMAL WITH NO SIGFNT CP AIRMASS MIXING  
IN.  
 

 
   
AVIATION /15Z WEDNESDAY THROUGH SUNDAY/
 
 
AT KCLT AND ELSEWHERE: NO CHANGES TO THE KCLT TAF FOR THE 15Z AMD.  
ITWS AND 5-MIN ASOS OBS INDICATING THAT WINDS CONTINUE TO FLIRT WITH  
270 DEGREES BUT ENOUGH OBS ON THE N SIDE TO GO AHEAD AND START WNW.  
OTHERWISE, VFR CONDITIONS WILL PERSIST THROUGH THE NEXT 24 HOURS.  
W/NW WINDS WILL DEVELOP AT ALL TERMINALS BY 15Z. SOME GUSTS IN THE  
MID TEENS WILL BE POSSIBLE AT THE FOOTHILLS AND PIEDMONT TERMINALS,  
WHILE GUSTS OF AROUND 20 KTS ARE EXPECTED TO DEVELOP WITHIN THE NEXT  
COUPLE OF HOURS AT KAVL. OTHERWISE, SCT/BKN CLOUDS IN THE 045-070  
RANGE WILL DISSIPATE BY LATE MORNING, AND MOST TERMINALS WILL SEE  
SKC CONDITIONS BY EARLY AFTERNOON, CONTINUING THROUGH THE EVENING,  
BEFORE HIGH CLOUDS BEGIN TO INCREASE TOWARD DAYBREAK THURSDAY.  
 
OUTLOOK: SURFACE LOW PRESSURE APPROACHING FROM THE SOUTHWEST WILL  
BRING CHANCES FOR WIDESPREAD PRECIP TO THE AREA THURSDAY AND FRIDAY.  
YET ANOTHER COLD FRONT WILL BRING CHANCES OF PRECIP AND RESTRICTIONS  
ON SUNDAY.  
 
CONFIDENCE TABLE...  
 
15-21Z 21-03Z 03-09Z 09-12Z  
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KAVL HIGH 100% HIGH 100% HIGH 100% HIGH 100%  
KHKY HIGH 100% HIGH 100% 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  
 

 
   
CLIMATE
 
 
ERATURE MIN TEMPERATURE  
STATION HIGH LOW HIGH LOW  
------- ---------- ---------- ---------- ----------  
KAVL 72 1933 20 1977 57 1943 0 1994  
KCLT 71 1937 23 1893 62 1943 10 2003  
KGSP 71 1928 30 1977 60 1943 5 1893  
 
RECORDS FOR 01-19  
 
MAX TEMPERATURE MIN TEMPERATURE  
STATION HIGH LOW HIGH LOW  
------- ---------- ---------- ---------- ----------  
KAVL 70 1974 21 1940 53 1907 -5 1994  
KCLT 69 1929 24 1994 54 1907 6 1994  
1907  
KGSP 72 1974 25 1994 54 1937 5 1994  
1907  
 
RECORDS FOR 01-20  
 
MAX TEMPERATURE MIN TEMPERATURE  
STATION HIGH LOW HIGH LOW  
------- ---------- ---------- ---------- ----------  
KAVL 69 1906 24 2009 53 1954 -13 1985  
1890  
KCLT 71 1951 30 1983 53 1890 -2 1985  
1929 1893  
1927  
KGSP 72 1933 30 1983 56 1922 1 1985  
 
RECORDS FOR 01-21  
 
MAX TEMPERATURE MIN TEMPERATURE  
STATION HIGH LOW HIGH LOW  
------- ---------- ---------- ---------- ----------  
KAVL 72 1927 8 1985 59 1927 -16 1985  
KCLT 73 1935 24 1985 58 1954 -5 1985  
KGSP 73 1927 26 1985 59 1933 -4 1985  
 
RECORDS FOR 01-22  
 
MAX TEMPERATURE MIN TEMPERATURE  
STATION HIGH LOW HIGH LOW  
------- ---------- ---------- ---------- ----------  
KAVL 73 1932 21 1960 59 1933 0 1970  
KCLT 74 1937 29 1970 60 1906 5 1970  
KGSP 72 1938 31 1970 58 1933 3 1893  
1921  
 
RECORDS FOR 01-23  
 
MAX TEMPERATURE MIN TEMPERATURE  
STATION HIGH LOW HIGH LOW  
------- ---------- ---------- ---------- ----------  
KAVL 73 1927 20 2005 54 1999 1 1936  
1936  
KCLT 75 1927 27 1970 59 1999 9 2003  
KGSP 73 1974 30 1970 58 1999 5 1893  
1927  
 
RECORDS FOR 01-24  
 
MAX TEMPERATURE MIN TEMPERATURE  
STATION HIGH LOW HIGH LOW  
------- ---------- ---------- ---------- ----------  
KAVL 74 1949 18 1963 54 1950 -7 1963  
KCLT 74 1967 26 1948 54 1909 7 1963  
KGSP 76 1967 26 1948 59 1974 9 2014  
1963  
 

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

 
 

 
SYNOPSIS...SBK  
NEAR TERM...JDL/TDP  
SHORT TERM...SBK  
LONG TERM...SBK  
AVIATION...JDL/TDP  
CLIMATE...  
 
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