Area Forecast Discussion
Issued by NWS Greer, SC
Issued by NWS Greer, SC
482 FXUS62 KGSP 191042 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 642 AM EDT Sun Jul 19 2026 .WHAT HAS CHANGED... Updated the aviation discussion for the 12z TAFs. && .KEY MESSAGES... 1. Hot and humid conditions with heat index values ranging from 100 to 105 degrees this afternoon. Elevated heat index values continue through Wednesday. Cooler temperatures later in the week should keep heat indices below 100 degrees. 2. Increased convective coverage expected today with some severe thunderstorms. Damaging winds are likely to be the main hazard. Elevated convective coverage continues Monday with a few severe storms. Typical diurnal shower and thunderstorm chances Tuesday, before a cold front brings increased coverage and the potential for more severe weather on Wednesday. && .DISCUSSION... Key message 1: Hot and humid conditions with heat index values ranging from 100 to 105 degrees this afternoon. Elevated heat index values continue through Wednesday. Cooler temperatures later in the week should keep heat indices below 100 degrees. Despite better convective coverage and associated cloud debris, along with lower thickness values, highs will reach the low to mid 90 today. With elevated dewpoints, heat index values over 100 are expected for much of the area. A few locations may briefly reach 105, but should be isolated enough to preclude a Heat Advisory. Highs cool further on Monday but spike back up a few degrees Tuesday and Wednesday. Heat index values will mostly be 100 or less Monday, but with the increased temps and lingering elevated dewpoints Tuesday and Wednesday, heat index increases back over 100 for many locations along and south of the I-85 corridor. Spotty 105 values are possible Tuesday, but the probability of needing a Heat Advisory looks low at this time. The heat and humidity finally break by Thursday with an air mass chance behind a cold front. Until then, stay hydrated, take frequent breaks in air-conditioned or shaded areas, and never leave children or pets unattended in vehicles. Key message 2: Increased convective coverage expected today with some severe thunderstorms. Damaging winds are likely to be the main hazard. Elevated convective coverage continues Monday with a few severe storms. Typical diurnal shower and thunderstorm chances Tuesday, before a cold front brings increased coverage and the potential for more severe weather on Wednesday. An upper trof digging into the northeast will push a weak front into the area from the north. The atmosphere will again become very unstable with an increase in bulk shear due to the trof and front. High PW values and steep low level lapse rates will create the threat for damaging downbursts. The increase in shear could bring some organization to the convection which could increase the severe storm potential. SPC has introduced a Slight Rise of severe storms as a result. The front stalls over the area Monday, but the shear weakens. However, the atmos remains very unstable with high PW values and steep low level lapse rates. SPC has a Marginal Risk for much of the area. Diurnal convective chances linger Tuesday but overall coverage should be lower. The chance ramps back up Wednesday as another trof digs into the eastern CONUS pushing yet another front into the area. The chance of strong to severe storms may ramp back up as well with a moist and unstable air mass and some organization possible. More typical diurnal convective trends return through the rest of the forecast period. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... At KCLT and elsewhere: Mountain valley fog/stratus has floated around KAVL this morning. Have a short TEMPO in place for this. Diurnal cumulus may form at MVFR to low VFR level in the morning before lifting, but chance too low for any cigs in the TAF for now. Similar coverage of showers/storms expected this afternoon, and all sites get a PROB30 for diurnal SHRA/TSRA. Mountain valley fog expected once again overnight. Light SW wind picks up speed by afternoon. KAVL sees NW wind. Outlook: Good coverage of afternoon/evening SHRA/TSRA continues Monday with less coverage expected on Tuesday before increasing again on Wednesday then lowering again Thursday. Low stratus and/or fog will be possible each morning, mainly in the mtn valleys. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ RWH