textproduct: Columbia

WHAT HAS CHANGED

Aviation discussion updated for 00Z TAF issuance.

KEY MESSAGES

- 1. Thunderstorms expected each day through the weekend with seasonable temperatures. Drier conditions and above normal temperatures are expected to start next week.

DISCUSSION

KEY MESSAGE 1: Thunderstorms expected each day through the weekend with seasonable temperatures. Drier conditions and above normal temperatures are expected to start next week.

A slow moving batch of convection remains in the Pee Dee this evening with impressive rainfall rates exceeding 2-3"/hr. This comes as lingering instability coupled with slow storm motions and PWAT's near 2.20" bring the locally heavy rainfall threat. This threat could persist for the coming 1-2 hours before mostly dry conditions are expected tonight. Cannot fully rule out a couple stray showers overnight into Friday morning, but impactful weather is not likely tonight.

The persistent trough is forecast to hang around through about Saturday, with a deep plume of moisture atop the area on Friday and Saturday still. As a result, scattered to numerous showers and thunderstorms are expected both days across the forecast area. High PWs can and should result in continued heavy rainfall across the area, which has result in parts of the area being included in a Marginal and Slight Risk for Excessive Rainfall through Saturday. Flash flooding likely won't be a widespread issue but storms should be efficient enough at producing rainfall to make any training or slow movers capable of flash flooding.

As we get later into the weekend and early next week, confidence continues to increase in anomalous upper level ridging building overhead and persisting. This 500 hPa ridge should yield above normal temperatures beginning Monday and persisting through the end of the forecast period. It is unlikely that we will see widespread precipitation to help keep temps down during this period as upper level subsidence beneath the ridge center should hold convection mostly at bay. Given this, the potential for anomalous heat is rising. Highs in the mid to upper 90s appear possible, as signaled by a pretty robust EFI signal at this timeframe. Given consistent dewpoints in the 70s, dangerous heat index values are again forecast to return to the forecast area during this period, especially Tuesday through Thursday of next week.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

Convection diminishes this evening with VFR conditions. Another round of stratus and patchy fog is expected tonight with cig/vsby restrictions before more showers/storms are possible Friday afternoon and evening.

Convection is decreasing in coverage this evening with light winds and debris cloudiness in place. A few stray showers overnight cannot be ruled out, but confidence in this is low. High low level moisture is expected to yield another round of stratus and patchy fog, especially where rain fell this afternoon. The latest HRRR runs are fairly aggressive in terms of timing, having stratus development as early as 03-06z, while LAMP guidance is a bit slower. Considering stratus developed in this earlier window last night with similar conditions expected tonight, leaned a bit more toward the earlier timeframe for onset. Overall, IFR to periods of LIFR cig and/or vsby restrictions will be possible mainly after 06z, continuing through 12-14z before gradually lifting through the morning and into the early afternoon. Winds late Friday morning pick up around 5-8 kts out of the south and another round of scattered convection is expected after 17-19z, which has been addressed with a PROB30 group at all sites for now.

EXTENDED AVIATION OUTLOOK... Restrictions possible from showers and thunderstorms into this weekend. Drier conditions expected early next week.

CAE WATCHES/WARNINGS/ADVISORIES

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