textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Updated the aviation discussion for the 12Z TAF issuance.

KEY MESSAGES

1. Hot and humid today with a return of showers and thunderstorms. Chances increase Saturday then diminish early next week. Temperatures fall to around normal Saturday with above normal temps returning next week.

DISCUSSION

Key message 1: Hot and humid today with a return of showers and thunderstorms. Chances increase Saturday then diminish early next week. Temperatures fall to around normal Saturday with above normal temps returning next week.

Hot and humid conditions continue today with low to mid 90s outside of the mountains and heat index values approaching 100 along and south of the I-85 corridor as a shortwave upper ridge builds over the area. Shower and thunderstorm chances return as a frontal boundary drops toward the area. Instability increases but shear remains weak. Still, steepening low level lapse rates will lead to the potential for a few strong to severe wet microbursts in storms that can grow tall enough. A shortwave trough moves into the area Saturday and a wave of low pressure moves into the area along the surface frontal boundary. This combined with deepening moisture will lead to an increase in convective chances into the evening. The deep moisture and increasing forcing will lead to some areas of heavy rainfall but diminishing severe storm chances.

An upper anticyclone builds just to our west with dry surface high pressure building into our area early next week. Mainly mountain isolated to scattered diurnal convection returns by the end of the week.

Temps cool Saturday with the increase in convection. Above normal temps return next week.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

At KCLT and elsewhere: VFR conditions will prevail through most of the forecast period with the exception of mountain valley fog/low stratus through daybreak. The mountain valley fog/low stratus did not make it to KAVL, so took out any mention of it in the 12Z update for this morning. Guidance has increased the coverage for showers and thunderstorms this afternoon and evening. As a result, placed a PROB30 for TSRA and associated restrictions at all Upstate TAF sites and KCLT. Lingering cloud debris through the evening and early portions of the overnight period is expected, with the potential for stratus to form and bring restrictions to portions of the area by daybreak Saturday.

Outlook: More widespread showers and thunderstorms expected across the area on Saturday, then scattered aftn/eve convection expected Sunday and Monday, mainly in the mountains. Morning fog/low stratus will be possible each day, especially in the mountain valleys.

GSP WATCHES/WARNINGS/ADVISORIES

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