textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

No significant changes to the forecast package.

KEY MESSAGES

1. Mainly diurnal shower and thunderstorm chances expected through the the week.

DISCUSSION

Key message 1: Mainly diurnal shower and thunderstorm chances expected through the the week.

A sharp trough will slowly move east across the area through Wednesday knocking down the upper ridge over the area today. At the surface, a weak backdoor front drops south toward the area today, then stalls over the area on Tuesday. The front then washes out on Wednesday with weak high pressure near or to our east. These features will keep a moist and unstable airmass over the area, leading to mainly diurnal convection each day. High PW values and slow moving storms could lead to some heavy rainfall. The threat of flooding is low, but minor flooding could develop if training cells develop or high rain rates linger over one area. The threat of severe storms looks minimal at best with weak instability and lapse rates. With morning clouds and an earlier start to convection, highs over the western portion of the CWFA will see highs near to a few degrees below normal. With more sun and a later start to convection, highs over the I-77 corridor will be around 90. Highs Tuesday will be below normal across the forecast area with low clouds and a cooler airmass. Highs Wednesday rise back to around normal.

Weak ridging returns Thursday before a series of shortwaves bring more zonal flow to the area. The moist and unstable airmass remains over the area with high pressure over or near the area and no significant frontal systems. This leads to continued chances of mainly diurnal convection each day. Highs rise to around 90 for many locations outside of the mountains Thursday through Sunday. Muggy dewpoints could lead to the potential for heat index values near 100, mainly south of the I-85 corridor for the weekend.

AVIATION /06Z MONDAY THROUGH FRIDAY/

At KCLT and elsewhere: Mainly cirrus will continue to stream over the area this morning, along with some VFR stratocu over the mountains and altocu over the Upstate and NE GA. Can't rule out a spotty shower over the western sites, but no restrictions expected. Guidance has backed off on any morning restrictions but did bring low VFR cigs to KAND. PROB30s continue for each site with a moist and unstable airmass during the afternoon and early evening. Winds are tricky with a weak boundary dropping south into the area. For now, it appears that winds will only go NE at KHKY with S to SE winds elsewhere. Even the wind at KHKY goes SE for the afternoon. Winds go light overnight.

Outlook: Diurnal convection and associated restrictions are expected each day this week. Widespread IFR ceilings will be possible Tuesday. Otherwise, mtn valley fog and low stratus will be possible each morning.

GSP WATCHES/WARNINGS/ADVISORIES

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