434
FXUS62 KGSP 142352
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
752 PM EDT WED APR 14 2021
SYNOPSIS
CONTINUED THREAT OF SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
LATE THIS AFTERNOON INTO TONIGHT AS A RELATIVELY DRY COLD FRONT
PASSES THROUGH WITH MUCH COOLER AND DRIER AIR BEHIND IT TO WRAP UP
THE WORK WEEK. UNSETTLED WEATHER MAY RETURN THIS WEEKEND AS BETTER
MOISTURE PUSHES IN FRIDAY NIGHT.
NEAR TERM /THROUGH THURSDAY/
AS OF 743 PM EDT WEDNESDAY: SOME PATCHES OF LIGHT RAIN WERE MOVING
EAST ACROSS THE MTNS AND UPSTATE, BUT MOST LOCATIONS WERE PROBABLY
ONLY GETTING LITTLE MORE THAN SPRINKLES. THIS TREND SHOULD CONTINUE
AS THE FRONT MOVES IN FROM THE WEST, SO THE PASSAGE OF THE FRONT
LOOKS TO BE UNIMPRESSIVE. A FEW CHANGES WERE MADE TO PRECIP PROBS
TO ACCOUNT FOR THE MODEL/RADAR TRENDS. AT THIS POINT, ONLY A
SMALL AREA NORTH OF I-40 AND EAST OF THE MTNS HAS ANY CHANCE FOR
A THUNDERSTORM.
OTHERWISE...MOST OF THE SHOWER ACTIVITY WITH THE PASSING UPPER WAVE
WILL MOVE EAST OF THE FORECAST AREA BY MIDNIGHT TONIGHT. HOWEVER,
LOWER-LEVEL MOISTURE WILL INCREASE POST-FROPA, WITH RESIDUAL
WESTERLY FLOW UPSLOPE SHOWERS LIKELY NEAR THE SPINE OF THE SOUTHERN
APPALACHIANS OVERNIGHT. AFTER SOME MORNING LINGERING CLOUDS,
POST-FROPA DRYING WILL WORK IN FROM THE WEST ON THURSDAY. DESPITE
MODEST DOWNSLOPE FLOW EAST OF THE MOUNTAINS, TEMPERATURES SHOULD
BE ABOUT 10 DEGREES COOLER THURSDAY AFTERNOON GIVEN THE FALLING
THICKNESSES WITH THE FROPA. EXPECT BREEZY CONDITIONS WITH MIXING
AS WELL.
SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/
AS OF 215 PM WEDNESDAY: CANADIAN HIGH PRESSURE BUILDS IN BEHIND THE
DEPARTING FROPA THURSDAY NIGHT INTO FRIDAY LEADING TO DRIER WEATHER
ACROSS THE REGION WHILE A LOW PRESSURE SYSTEM TO OUR NORTH TRACKS
EAST ACROSS THE NORTHEASTERN CONUS. BREEZY WINDS WILL CONTINUE
THURSDAY EVENING INTO THE OVERNIGHT HOURS WITH THE HIGHEST GUSTS
OCCURRING IN THE MOUNTAINS. PATCHY FROST REMAINS POSSIBLE ACROSS THE
NC MTNS EARLY FRIDAY MORNING DUE TO LOWS DROPPING INTO THE MID TO
UPPER 30S. SOME LOCATIONS COULD SEE SLIGHTY LOWER TEMPS RANGING FROM
THE UPPER 20S TO LOWER 30S. IT IS IMPORTANT TO NOTE THAT LOW
DEWPOINTS ALONG WITH INCREASING CLOUD COVER AND BREEZY WINDS COULD
LIMIT FROST FORMATION. LOWS ELSEWHERE FRIDAY MORNING SHOULD RANGE
FROM THE UPPER 30S TO MID 40S. THE MAIN STORY FOR FRIDAY WILL BE
CONCERNS FOR FIRE WX AS RH VALUES IN MOST LOCATIONS WILL BE IN THE
MID TO UPPER 20S. WINDS SHOULD REMAIN FAIRLY BREEZY FRIDAY MORNING,
HOWEVER THEY SHOULD GRADUALLY RELAX THROUGHOUT THE DAY. HIGH TEMPS
FRIDAY SHOULD BE A FEW DEGREES BELOW CLIMATOLOGY.
SATURDAY A WARM FRONT WILL BE OVER THE FLORIDA PANHANDLE WHILE AN
AREA OF LOW PRESSURE TRACKS EASTWARD ACROSS THE MIDWEST. THESE TWO
SYSTEMS WILL INTERACT WITH EACH OTHER LEADING TO AN INCREASE IN RAIN
CHANCES ACROSS THE FORECAST AREA. BOTH INSTABILITY AND MOISTURE LOOK
LIMITED AGAIN WITH THIS EVENT. MODELS ARE NOT IN GOOD AGREEMENT IN
REGARDS TO THE OVERALL COVERAGE OF RAIN ACROSS THE CWA; HOWEVER, THE
MAJORITY OF MODELS SHOW POPS OCCURRING OVER THE REGION WITH THE
EXCEPTION OF THE CANADIAN WHICH LOOKS TO BE THE OUTLIER. HIGHS ON
SATURDAY WILL BE ROUGHLY 6 TO 8 DEGREES BELOW CLIMATOLOGY.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
AS OF 2PM EDT WEDNESDAY: EXTENDED FORECAST IS MOSTLY DRY AND A
LITTLE ON THE COOL SIDE FOR THIS TIME OF YEAR. BROAD LONG WAVE
UPPER PATTERN HAS A MEAN TROUGH OVER THE EASTERN CONUS SATURDAY
NIGHT THAT GENERALLY DEEPENS THROUGH MID-WEEK, INTERRUPTED BY
OCCASIONAL EMBEDDED SHORTWAVES AND ASSOCIATED WEAK FRONTAL PASSAGES.
MOISTURE NEVER RECOVERS VERY MUCH AND CHANCES FOR ANY SIGNIFICANT
PRECIPITATION ARE LOW. BEST CHANCES FOR RAIN APPEARS TO BE SUNDAY
OR MONDAY (DEPENDING ON WHICH MODEL IS CONSULTED) AS A FAIRLY POTENT
SHORTWAVE CROSSES THE SOUTHERN APPALACHIA, WITH LITTLE MOISTURE TO
WORK WITH, AND NO CONVECTIVE INSTABILITY. WINDS WILL GENERALLY BE
LIGHT THROUGH THE EXTENDED AS WELL, AND MORE GENERALLY LIGHT
NORTHERLY TO NORTHWESTERLY.
AVIATION /00Z THURSDAY THROUGH MONDAY/
AT KCLT AND ELSEWHERE: VFR AT ALL TERMINALS THROUGH THE
PERIOD. LIGHT PRECIP MOVING IN FROM THE WEST MAY AFFECT ALL
SITES THROUGH THE MID/LATE EVENING, BUT WITH LITTLE CHANCE OF A
VISIBILITY OR CEILING RESTRICTION. INSTEAD, A MID-LEVEL CEILING IS
EXPECTED. WIND WILL BE SW OR SSW UNTIL THE BOUNDARY PASSES LATE THIS
EVENING AND THE WIND COMES AROUND TO W OR WNW. THE MID-LEVEL CLOUDS
WILL PERSIST INTO THURSDAY BEFORE DRYING OCCURS AND THE CLOUD DECK
MOVES EAST. ONCE THAT HAPPENS, IN THE MIDDLE PART OF THE AFTERNOON,
WE SHOULD SEE OCCASIONAL WIND GUSTS AS MIXING BECOMES DEEP ENOUGH TO
TAP INTO STRONGER WINDS ALOFT. SKY SHOULD CLEAR LATE IN THE PERIOD.
OUTLOOK: DRY/VFR CONDITIONS CONTINUE INTO FRIDAY NIGHT. A LOW
PRESSURE SYSTEM PASSING SOUTH OF THE AREA COULD BRING A ROUND OF
PRECIPITATION AND RESTRICTIONS OVER THE WEEKEND, BUT CONFIDENCE
IN THIS SCENARIO IS VERY LOW AT THIS TIME, WITH LOW CONFIDENCE
CONTINUING INTO EARLY NEXT WEEK.
CONFIDENCE TABLE...
00-06Z 06-12Z 12-18Z 18-00Z
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAVL HIGH 96% HIGH 93% 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 99% 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 ARE AVAILABLE AT
THE FOLLOWING LINK:
WWW.WEATHER.GOV/GSP/AVIATION
FIRE WEATHER
WITH DEWPOINT MIXING OCCURRING THIS AFTERNOON, THE RH MAY BRIEFLY
TOUCH 25% IN A FEW LOCATIONS LATE THIS AFTERNOON. IN ADDITION,
MIXING WILL PERMIT GUSTS IN THE UPPER TEENS TO NEAR 20 MPH TO
DEVELOP AT TIMES. DRY AND BREEZY CONDITIONS WILL CONTINUE THURSDAY
AND FRIDAY. CONDITIONS SHOULD REMAIN JUST SHORT OF FIRE DANGER OR
RED FLAG LEVELS.
EQUIPMENT
THE RADAR AT WFO GSP IS CURRENTLY DOWN DUE TO EQUIPMENT FAILURE.
TECHNICIANS ARE WORKING ON THE ISSUE BUT PARTS MAY NEED TO BE
ORDERED AND THE RADAR MAY REMAIN DOWN FOR 1 TO 3 DAYS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...MPR
NEAR TERM...HG/PM
SHORT TERM...AP
LONG TERM...WJM
AVIATION...PM
FIRE WEATHER...
EQUIPMENT...
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