textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Updated aviation discussion with the 18z TAF issuance.

Conditions are trending drier after Tuesday and into next weekend.

KEY MESSAGES

1. A few scattered showers and thunderstorms possible through this evening. Cooler and drier weather returns Sunday before rain chances increase Monday. 2. Drier and cooler than normal weather after Tuesday with slight rain chances possible toward the end of next week.

DISCUSSION

Key message 1: A few scattered showers and thunderstorms possible through this evening. Cooler and drier weather returns Sunday before rain chances increase Monday.

An area of high pressure off to the norther continues to expand southward, bringing a backdoor cold front through the area tonight and into Sunday. Ahead of it, a few showers and thunderstorms are expected, especially along the frontal boundary as it moves south/southwest. The overall environment ahead of the front is rather benign, but some instability during the afternoon hours around peak heating time could contribute to a few storms producing cloud to ground lightning. Model guidance shows very weak mid level and upper flow with the boundary layer almost calm. Additionally, DCAPE is expected to be low, less than 400 J/kg, indicating a rather low chance for any microbursts. Overall, anything that does manage to form this afternoon and evening ahead of the front should be short lived and produce minimal hazards.

As the front continues to move through tonight, drier and cooler air arrive for Sunday. Model guidance has the boundary stalling over the far southern locations of the CWA, making way for a slight chance (15-35%)of precipitation. Cannot rule out a brief shower Sunday, but confidence is low. By Monday, rain chances increase again as the airmass modifies. Expect temperatures to remain somewhat cooler than normal.

Key message 2: Drier and cooler than normal weather after Tuesday with slight rain chances possible toward the end of next week.

Once increased rain chances dissipate Monday night, the general pattern looks to keep the area in a drier pattern for the majority of next week and into the start of the weekend. High pressure returns from the north and spreads southward, shunting the majority of rain chances once again. Long range models suggest a spin up of a coastal low off the Carolinas toward mid week. At this time, the high pressure looks to dominate and it would not have any impact to this area. This will be monitored, mainly for rain concerns east of the mountains. Should high pressure weaken, it could allow for this area to shift westward into the eastern fringe of the CWA and increase rain chances. If high pressure remains steady, it would shunt rain chances. But either way, not looking at anything impactful at this time. Expect temperatures to remain cooler and slightly below normal.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

At KCLT and elsewhere: VFR conditions are expected to prevail through the majority of the TAF period. A few scattered showers and TSRA this afternoon and evening ahead of a cold front moving in from the N/NE. For this, a TEMPO for TSRA at KGSP/KGMU/KAND from 18z-22z as confidence is higher during that time. As the front moves through, expect a wind shift out of the N/NE at all sites. Low end gusts of 15-20kts are possible overnight at most sites east of the mountains, but should diminish after 12z-13z. Winds start to become more SE toward Sunday afternoon.

Outlook: Another round of showers and thunderstorms are possible Monday. A drier pattern should return for the rest of the workweek.

GSP WATCHES/WARNINGS/ADVISORIES

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