textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Updated aviation discussion for the 12z TAF issuance.

KEY MESSAGES

1. A few thunderstorms for isolated locations in the mountains and showers elsewhere through tonight. Rain chances remain in place for the majority of the area through Thursday. 2. Much cooler temperatures through next week with a drier pattern emerging by the weekend.

DISCUSSION

Key message 1: A few thunderstorms for isolated locations in the mountains and showers elsewhere through tonight. Rain chances remain in place for the majority of the area through Thursday.

The upper pattern parks a ridge to the west and a trough to the northeast, with the CWA sandwiched in the middle for the next several days. At the surface, a strong area of high pressure over Canada and a strong area of low pressure off the east coast, classic rex block. What this means for the CWA is a strong cold air damming event through at least Friday. Northeast surface winds and lingering moisture means a couple days with on and off showers. Some guidance still wants to develop a small amount of elevated instability over the wedge and contribute to a few rumbles of thunder, but confidence is low. Guidance also keeps instability over the mountains, where to CAD is less influential. Cannot rule out a thunderstorms in the far western NC mountains. Any storm that does develop could produce strong winds and locally heavy rainfall. Locations east of the mountains are expected to have more non-convective rainfall, reducing rain rates and the flooding risk. But the risk is nonzero. Still could have something pop up, especially along the Escarpment. As with any CAD event, air being pushed up against the terrain could create locally rooted showers that persist a while. This has the potential to create a very low flood risk, but again, confidence is still low due to the non-convective nature of these showers. Will continue to monitor.

Key message 2: Much cooler temperatures through next week with a drier pattern emerging by the weekend.

Daily highs are going to be a chef's kiss for autumn lovers. Daily highs in the 60s for the NC Piedmont and low 70s in parts of the Upstate/Northeast Georgia. These cooler temps look to remain in place with the CAD through at least Friday. Once the area of low pressure off the east coast lifts further north, warmer temps trend through the middle of next week. However, these look to be closer to normal and not the oppressive heat from the summer. Also, with the northerly winds, drier air remains locked in through at least Tuesday, meaning humidity should be lower. As for the overnight lows, these are trending cooler, into the 50s and even 40s for the mountains and NC Piedmont into the weekend. The cooler temps stick around until at least Tuesday.

AVIATION /10Z WEDNESDAY THROUGH SUNDAY/

At KCLT and elsewhere: Though brief periods of MVFR could occur, IFR is expected to prevail at all sites through the end of the TAF period. Expect BKN/OVC with 006-009 cigs. Stronger northeast winds should maintain mostly VFR/MVFR vsby for low stratus. -DZ and -SHRA prevail at all sites as well. Gusts of 15-25kts remain in place for all sites except KAVL through the end of the period as well.

Outlook: Restrictions may improve Thursday afternoon/evening with VFR returning by Friday. Drier conditions return Friday into the weekend, though mountain/river valley fog/stratus could still develop near daybreak each day.

GSP WATCHES/WARNINGS/ADVISORIES

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