textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Overall storm chances lower through this evening.

Heat index values trending slightly lower for Thursday but higher for Friday.

Updated the aviation discussion for the 18z TAFs.

KEY MESSAGES

1. Showers and thunderstorms possible through this evening, with a few possibly severe. Daily thunderstorms are also possible each afternoon through the end of the week. 2. Hot conditions continue into next week with triple digit heat index values expected.

DISCUSSION

Key message 1: Showers and thunderstorms possible through this evening, with a few possibly severe. Daily thunderstorms are also possible each afternoon through the end of the week.

Another round of thunderstorms are possible through the evening as the CWA remains downstream of the ridge out west. However, initiation will be later than usual due to the morning clouds slowing heating and developing instability. Can't rule out a few severe storms given the DCAPE values in place. As for the remainder of the week, the ridge starts to shift eastward and shuts off the MCS conveyer belt. Given the open warm sector remaining through Friday, daily chances for more typical summertime showers and thunderstorms are expected. The higher chances are as usual, over the mountains, with a few pop up showers possible outside the mountains. Chances increase Saturday as a weak boundary drops into the area. The probabilities return to more typical diurnal chances next week as the boundary dissipates.

Key message 2: Hot conditions continue into next week with triple digit heat index values expected.

Thursday and Friday, an upper ridge moves over the southeast and high pressure continues to build. With these height rises returning, hotter temperatures do as well. Current guidance shows low to mid 90s for most locations east of the mountains on Thursday and mid to upper 90s on Friday. Model blend dew points still look too high, but even going with the more likely numbers, heat index values over 100 are expected outside the mountains. A few locations may briefly reach 105. Friday will be the hotter of the two days with heat index values potentially 105 or higher along and south of the I-85 corridor. If these trends continue, then a Heat Advisory would be needed Friday. Highs may drop a few degrees with a weak boundary in the area Saturday, but humidity remains high. The heat returns next week with high humidity continuing. This keeps the potential for triple digit heat index values in play. Additional Heat Advisories may be needed should these trends continue.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

At KCLT and elsewhere: Upstream convection has dissipated with VFR clouds spreading across the area. Guidance still shows isolated to scattered coverage across the area late this afternoon into the early evening. Have retained PROB30s for all but KAVL but trended later than previously expected. Have also retained early morning MVFR TEMPO IFR restrictions at KAVL with VFR elsewhere. Gusty N wind at KAVL becomes light N by evening. Elsewhere W to NW wind becomes light and variable overnight. N to NW wind picks back up on Thursday.

Outlook: A few showers or thunderstorms possible each afternoon with flight restrictions possible for low stratus and fog each morning.

GSP WATCHES/WARNINGS/ADVISORIES

GA...None. NC...None. SC...None.