317
FXUS62 KGSP 181054
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
654 AM EDT THU JUN 18 2026
WHAT HAS CHANGED
CONFIDENCE INCREASING THAT THE REMNANTS OF ARTHUR WILL TRACK
THROUGH THE FORECAST AREA TONIGHT.
THE QPF AMOUNTS FOR TONIGHT HAVE TRENDED UP SLIGHTLY.
THE AVIATION DISCUSSION WAS UPDATED FOR THE 12Z TAF ISSUANCE.
KEY MESSAGES
1. RAIN CHANCES INCREASE THIS AFTERNOON THROUGH TONIGHT AS THE
REMNANTS OF TROPICAL STORM ARTHUR CROSS THE AREA. WIDESPREAD
RAINFALL AND EMBEDDED THUNDER ARE EXPECTED; INSTANCES OF LOCALLY
HEAVY RAINFALL AND DAMAGING WIND CANNOT BE RULED OUT. A COLD
FRONT WILL BRING AN END TO THE RAIN BY LATE FRIDAY.
2. DRY CONDITIONS BRIEFLY SETTLE OVER THE AREA SATURDAY, THEN
DIURNAL RAIN CHANCES RETURN SUNDAY AND CONTINUE THROUGH THE MIDDLE
OF NEXT WEEK.
3. INCREASED FIRE DANGER THIS AFTERNOON ACROSS THE NC PIEDMONT,
AS STRONG GUSTY WINDS AND HOT TEMPERATURES OVERLAP WITH CRITICALLY
DRY FUELS.
DISCUSSION
KEY MESSAGE 1: RAIN CHANCES INCREASE THIS AFTERNOON THROUGH TONIGHT
AS THE REMNANTS OF TROPICAL STORM ARTHUR CROSS THE AREA. WIDESPREAD
RAINFALL AND EMBEDDED THUNDER ARE EXPECTED; INSTANCES OF LOCALLY
HEAVY RAINFALL AND DAMAGING WIND CANNOT BE RULED OUT. A COLD FRONT
WILL BRING AN END TO THE RAIN BY LATE FRIDAY.
POST-TROPICAL CYCLONE ARTHUR IS NOW BEGINNING TO GET STEERED
BY WESTERLY FLOW OVER THE LOWER MS VALLEY. THE LATEST GUIDANCE
IS IN DECENT AGREEMENT THAT THE REMNANTS OF THIS SYSTEM WILL
TRACK EAST-NORTHEAST TODAY AND CROSS THE SOUTHERN PART OF THE
FORECAST AREA TONIGHT. AHEAD OF THE SYSTEM, STRATUS IS EXPECTED TO
DEVELOP ACROSS THE SOUTHERN HALF OR SO OF THE AREA, THEN SCATTER
OUT LATER THIS MORNING, LEAVING PARTLY CLOUDY SKIES. UNUSUALLY
STRONG LOW-LEVEL FLOW FOR THIS TIME OF YEAR WILL BE IN PLACE. EVEN
SHALLOW MIXING WILL TAP INTO WINDS AROUND 25-30 KT THIS MORNING
THRU THE AFTN. THE WINDY CONDITIONS COMBINED WITH ONGOING DROUGHT
WILL RESULT IN INCREASED FIRE DANGER FOR THE NC PIEDMONT (SEE KEY
MESSAGE 3). TEMPS WILL TOP OUT IN THE UPPER 80S TO LOWER 90S AND
WILL COMBINE WITH INCREASING DEWPTS TO MAKE IT FEEL MORE HUMID
TODAY. HEAT INDEX VALUES ARE EXPECTED TO STAY BELOW 105, BUT COULD
FLIRT WITH 100-102 ACROSS THE I-77 CORRIDOR THIS AFTN.
THE LATEST CAMS SEEM TO BE A LITTLE SLOWER IN CONVECTIVE INITIATION
AHEAD OF ARTHUR THIS AFTN. WHAT DOES DEVELOP DOESN'T LOOK ALL
THAT STRONG OR ORGANIZED, BUT WITH UP TO 2000 J/KG OF CAPE, CANNOT
RULE OUT A FEW STRONG TO SEVERE STORMS. DAMAGING WIND GUSTS WILL
BE THE MAIN THREAT
THE MAIN PRECIP ASSOCIATED WITH THE REMNANTS OF ARTHUR LOOK TO COME
IN LATE THIS EVENING. A CLOSED LOW AND CIRCULATION IS DEPICTED ON
MOST OF THE GUIDANCE, AND THE CENTER TRACKS NEAR THE I-85 CORRIDOR
OR JUST TO THE SOUTH OVERNIGHT. THE TROPICAL MOISTURE SHOULD MAKE
FOR EFFICIENT/HEAVY RAIN RATES, AND THERE STILL MAY BE A CORRIDOR
THAT LOCALLY SEES 2-3" OF RAINFALL IN A 3-6-HR PERIOD. THAT MAY
RESULT IN SOME EXCESSIVE RAINFALL, WITH A SLIGHT RISK NOW OUT
FOR THE ENTIRE AREA ON THE NEW DAY 1 OUTLOOK. THE SYSTEM WILL BE
MOVING STEADILY AND THE EXACT LOCATIONS OF ANY ENHANCED RAINFALL
ARE STILL TOO MUCH IN DOUBT TO WARRANT A FLASH FLOOD WATCH. THE
SYSTEM WILL PROVIDE ENHANCED LOW-LEVEL SHEAR THAT COULD RESULT IN
A NON-ZERO DAMAGING WIND AND TORNADO THREAT. BUT INSTABILITY WILL
BE WEAK AND THE CAMS SHOW LITTLE IN THE WAY OF UPDRAFT HELICITY
STREAKS OVER OUR AREA.
THE REMNANTS OF ARTHUR SHOULD EXIT TO THE EAST BY AROUND 12Z FRIDAY,
JUST AS A COLD FRONT DROPS IN FROM THE NW. THE LATEST CAMS, ALONG
WITH THE NAM AND CANADIAN DEVELOP A FEW SHOWERS AND POSSIBLY
THUNDERSTORMS ALONG THE FRONT ACROSS OUR FAR SOUTHEAST ZONES
FRIDAY AFTN BEFORE THE FRONT CLEAR THE FORECAST AREA. WHATEVER
DOES DEVELOP IS NOT EXPECTED TO BE SEVERE. LATER IN THE DAY,
CONDITIONS SHOULD COMPLETELY DRY OUT. MIN TEMPS WILL BE SLIGHTLY
ABOVE NORMAL WITH THE TROPICAL AIR MASS, BUT TOP OUT JUST AROUND
NORMAL FRIDAY WITH DECREASING HUMIDITY.
KEY MESSAGE 2: DRY CONDITIONS BRIEFLY SETTLE OVER THE AREA SATURDAY,
THEN DIURNAL RAIN CHANCES RETURN SUNDAY AND CONTINUE THROUGH THE
MIDDLE OF NEXT WEEK.
HIGH PRESSURE CROSSES THE AREA ON SATURDAY, RESULTING IN A DRY
DAY. BUT DIURNAL CONVECTIVE CHANCES LIKELY RETURN ON SUNDAY, AT
LEAST IN THE MOUNTAINS, AS THE PATTERN WILL REMAIN QUASI-ZONAL
WITH A SERIES OF SHORTWAVES TRACKING THRU THE MIDDLE AND EASTERN
PART OF THE CONUS. A STRONGER WAVE WILL CROSS THE AREA ON MONDAY
AND BRING A WEAK COLD FRONT IN FROM THE NW. THE FRONT WILL LIKELY
STALL OVER THE SOUTHEAST TUESDAY, AND GRADUALLY WASH OUT BY LATE
IN THE WEEK. POPS WILL BE NEAR TO SLIGHTLY ABOVE CLIMO IN THIS
PATTERN WITH TEMPS NEAR NORMAL. TYPICAL SUMMERTIME ISOLATED PULSE
SEVERE AND LOCALLY HEAVY RAIN THREAT WILL LIKELY EXIST TO SOME
EXTENT NEARLY EVERY DAY NEXT WEEK.
KEY MESSAGE 3: INCREASED FIRE DANGER THIS AFTERNOON ACROSS THE NC
PIEDMONT, AS STRONG GUSTY WINDS AND HOT TEMPERATURES OVERLAP WITH
CRITICALLY DRY FUELS.
GUSTY SOUTHWEST WINDS, POSSIBLY 25-35 MPH AT TIMES, ARE EXPECTED
ACROSS WESTERN NC TODAY. WHILE RH VALUES ARE EXPECTED TO BE MOSTLY
OVER 40% AND THUS ABOVE TYPICAL CRITICAL THRESHOLDS, THE ONGOING
SEVERE-TO- EXTREME DROUGHT ACROSS THE NC PIEDMONT AND EXCEPTIONALLY
DRY FUELS COMBINED WITH THESE GUSTY WINDS WILL LEAD TO AN INCREASED
RISK OF FIRE IGNITION AND ADVERSE FIRE BEHAVIOR. THIS RISK WILL
BE AMPLIFIED BY ERRATIC AND SHIFTING WINDS AND GUSTS IN AND NEAR
THUNDERSTORMS LATE AFTN INTO THIS EVENING. AFTER COORDINATION WITH
WFO RAH, WHO COORDINATED WITH THE NC FOREST SERVICE AND THEIR
FIELD OPERATIONS STAFF, HAVE ISSUED A FIRE DANGER STATEMENT FOR
THE NC PIEDMONT FROM 10 AM TO 6 PM TODAY TO ADDRESS THE INCREASED
FIRE DANGER.
AVIATION /12Z THURSDAY THROUGH MONDAY/
AT KCLT AND ELSEWHERE: MVFR STRATUS HAS SPREAD IN ACROSS THE
PIEDMONT AS EXPECTED. THE CLOUDS MAY TAKE A LITTLE LONGER THAN
PREVIOUSLY FORECAST TO SCATTER OUT, AS GUIDANCE HAS TRENDED MORE
TOWARD 15Z. CANNOT RULE OUT IFR CIGS BRIEFLY, AS SOME METARS SHOW
CIGS NEAR 1000 FT IN SPOTS. WILL CONTINUE TO JUST MENTION A FEW
IFR CLOUDS IN THE TAFS.
SW WINDS EXPECTED TO BECOME GUSTY AT ALL SITES (IF THEY AREN'T
ALREADY) WITH GUSTS TO AROUND 25 KTS EXPECTED AT MOST SITES DURING
THE AFTERNOON. GUIDANCE CONTINUES TO TREND LATER WITH ARRIVAL/ONSET
OF CONVECTION LATE THIS AFTN. MINOR TWEAKS WERE MADE TO THE PROB30
GROUPS. CONFIDENCE MAY INCREASE ENOUGH FOR SOME OF THEM TO BE
CONVERTED TO TEMPOS LATER TODAY.
STILL EXPECTING THE REMNANTS OF T.S. ARTHUR TO CROSS THE
AREA OVERNIGHT TONIGHT. EXPECT CIGS LOWER TO MVFR AS LIGHT
TO MODERATE SHRA MOVE IN FROM THE WEST, AND LOWER FURTHER TO
IFR OVERNIGHT. WINDS WILL BE TRICKY, AS A CLOSED CIRCULATION IS
EXPECTED WITH THE SYSTEM AND MAY BRING WINDS AROUND THE DIAL FROM
SW TO SE TO NE, THEN FINALLY NW BEFORE 12Z FRIDAY. CANNOT RULE OUT
SOME EMBEDDED THUNDER, BUT WILL HOLD OFF ON PROB30S, SINCE WE HAVE
THEM FOR THE DIURNAL CONVECTION TODAY.
OUTLOOK: A COLD FRONT WILL PUSH THRU THE AREA ON FRIDAY, AND COULD
TRIGGER SOME CONVECTION AROUND KCLT, BUT OVERALL, MOSTLY SOUTH OF
THE AREA. THEN, DRY AND RELATIVELY INACTIVE WEATHER WILL RETURN
BY FRI NIGHT AND CONTINUE THROUGH AT LEAST SAT NIGHT. DIURNAL
CONVECTION IS EXPECTED TO RETURN EARLY NEXT WEEK.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...INCREASED FIRE DANGER FROM 10 AM THIS MORNING TO 6 PM EDT THIS
EVENING FOR NCZ036-037-056-057-068>072-082.
SC...NONE.
ARK
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