Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
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441 FXUS62 KGSP 171743 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 143 PM EDT Tue Sep 17 2024 .SYNOPSIS... The remnants of the coastal low will meander over the region and keep elevated rain chances across the area into tonight. By Wednesday, the remnant low will stall out over the Mid-Atlantic, while high pressure begins to build into the region from the north and west late in the week giving our region a dry weekend. && .NEAR TERM /THROUGH TONIGHT/... Key Messages: 1) Remnants of Potential Tropical Cyclone Eight Continue Weakening as it Drifts Across the Western Carolinas 2) Additional Flooding is not Expected Due to Low Rain Rates As of 1200 PM EDT Tuesday: Made some minor tweaks to PoPs based on the latest KGSP radar loops. Otherwise, the forecast remains on track this afternoon. For the rest of today, the story will be a generally low overcast sky with spotty light rain/drizzle lingering across much of the forecast area. The remnants of PTC 8 will remain stalled over the Upstate this afternoon, then wobble east and then north tonight. Additional showers are progged to form mainly on the west and north sides of the circulation, which means highest PoPs will extend from the northern Upstate thru the Central and Northern NC Mountains. The southern Upstate and the Charlotte area should be on the drier side of the circulation, but still could see a few periods of light rain or drizzle. Highs will be well-below normal under the clouds. Tonight, with the low still wobbling over the area, continued cloudy skies and showery conditions expected. QPF should be light. Lows will be slightly above normal. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 135 AM EDT Tuesday: The leftovers from Potential Tropical Cyclone 8 will evolve into a weak closed upper low centered right over the CFWA and meander over the area through the day Wednesday into Wednesday night. The combination of the closed upper low and above-normal PWAT values (~1.50"-1.75") will support elevated coverage of showers, which is represented well with likely PoPs (55%-70%) over the NC mountains and chance PoPs (25%-54%) elsewhere. Model guidance suggests a few hundred joules per kilogram of instability may develop across the CFWA during peak heating Wednesday, which could lead to a few embedded thunderstorms as well. Rain chances will linger into the nighttime period Wednesday as the upper closed low begins to open up into a shortwave trough and gradually lift into the northeastern CONUS by late Thursday. Dry air entrainment will begin to take place as upper/mid-level north-northwesterly flow filtering in as the shortwave trough axis shifts east of the CFWA. Lingering showers may remain in place over the favorable upslope regions over the mountains late Thursday, but the expectation is that rest of the area will dry out by the end of the forecast period. Temperatures are expected to remain a few ticks below normal for afternoon highs both Wednesday and Thursday, while overnight lows run at or slightly above normal thanks to extensive cloud cover and increased rain chances. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 300 AM EDT Tuesday: Changes in the synoptic pattern becomes evident in the extended forecast period as any lingering upper troughiness begins to lift out the region and a stout upper anticyclone sets up shop over northern Mexico and the Southern Plains. Over the weekend, the upper anticyclone will pivot eastward and allow for gradual height rises to move into the southeastern CONUS. At the same time, weak surface ridging will result in a drier airmass and lead to much improved sensible weather conditions with afternoon highs and overnight lows at or slightly below normal for much of the medium range. The upper ridge over the central CONUS will begin to breakdown and large scale changes start to take place beyond D7, but the current D4-D7 deserves two thumbs up. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... At KCLT and elsewhere: Another messy 18Z TAF forecast can be expected thanks to the remnants of Potential Tropical Cyclone (PTC) Eight meandering over the western Carolinas. Seeing BKN to OVC IFR to MVFR clouds across the terminals this afternoon with -SHRA confined to the SC Upstate terminals and KAVL. Have TEMPOs through 22Z across the SC Upstate terminals for -SHRA and IFR cigs with prevailing -SHRA and MVFR cigs at KAVL through 00Z. Most terminals, except KAVL, will likely see a brief period of drier conditions this evening before moisture returns overnight. Both cigs and vsbys should gradually lower late this evening into the overnight hours with the return of -SHRA. Thus, have PROB30s across all terminals overnight to account for LIFR/IFR vsbys and cigs. -SHRA looks to linger through at least Wednesday morning, which will act to keep LIFR to IFR cigs and vsbys around so have TEMPOs during the morning hours on Wednesday for all terminals. Restrictions will once again be slow to improve on Wednesday, but by the afternoon and early evenings hours vsbys/cigs should gradually improve to MVFR to VFR levels. Wind direction will be primarily NE across the SC Upstate terminals through Wednesday while winds at KHKY and KCLT will generally be E/ESE. Winds at KAVL will generally have a N`ly component and will be VRB at times. Outlook: A weak upper low will lift northeast late Wednesday into Thursday. Restrictions return again Wednesday night into Thursday. On Friday, sfc high pressure builds into the area from the north allowing drier weather and VFR conditions to return. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...DEO NEAR TERM...AR/ARK SHORT TERM...CAC LONG TERM...CAC AVIATION...AR