textproduct: Columbia

WHAT HAS CHANGED

Added a second key message to discuss the increased rain chances and potential for cooler temperatures associated with a frontal boundary. Aviation discussion updated for 06z TAFs.

KEY MESSAGES

- 1. Hot and breezy conditions continue through the end of the week with isolated thunderstorms possible today and tomorrow.

- 2. A frontal boundary brings higher rain chances for the weekend followed by increasingly likely cooler temps.

DISCUSSION

Key Message 1: Hot and breezy conditions continue through the end of the week with isolated thunderstorms possible today and tomorrow.

An mid to upper level trough over the Tennessee Valley continues to slowly trek eastward today, gradually flattening out the ridge overhead. As the trough moves eastward, it is expected to absorbed into a larger scale trough in the northern stream. A weak surface trough is anticipated to develop through the end of the week in response, leading to breezy conditions and the chance for isolated thunderstorms both today and Friday. Despite the trough moving overhead, 850mb temps are forecast to be around 21-23C, which should lead to surface temps in the upper 90s today and tomorrow. Dew points are forecast to be in the upper 60s to around 70F, resulting in heat indices in the 100-105F range both afternoons. Continue to take precautions if you need to spend prolonged time outdoors the next couple of days.

Thunderstorm coverage the next couple of days doesn't look to be very high due to weak forcing mechanisms. However, forecast soundings show an inverted V profile, indicating the potential for some stronger winds with and storms that are able to develop.

Key Message 2: A frontal boundary brings higher rain chances for the weekend followed by increasingly likely cooler temps.

A frontal boundary draped over the Upper Midwest early this morning is forecast to get pushed southward from a shortwave moving from the Great Lakes into the Southeast through the weekend. As the front and associated upper trough approach the area, more widespread shower and thunderstorm activity can be anticipated for the weekend. This activity could linger into early next week as latest guidance indicates that the front stalls out near the area. In addition to the increased rain chances, it looks increasingly likely that we'll see cooler temps. The NBM interquartile range (IQR) on Monday ranges from the low to mid 80s to around 90F for the area. Given the recent hot temps, the NBM takes that into account and will likely have a warm bias. So, I would not be surprised if we end up toward the cooler end of the IQR.

AVIATION /06Z THURSDAY THROUGH MONDAY/

VFR conditions expected through the TAF period.

Mostly clear skies expected through mid morning then diurnal cumulus expected to develop with strong heating again today. A 20 knot low level jet is supporting surface winds around 5 knots which should increase to around 10 knots by 15z. Gusty winds are again expected by midday with southwesterly winds increasing to around 12-13 knots with gusts to 20-25 knots through the afternoon. Hi-res guidance suggesting some convection impacting the CSRA late afternoon so have included a PROB30 group there. Winds should subside after sunset but remain up around 5 to 7 knots overnight with a strong low level jet forecast. Otherwise VFR conditions expected.

EXTENDED AVIATION OUTLOOK...Increasing chances for afternoon storms this weekend and into early next week.

CAE WATCHES/WARNINGS/ADVISORIES

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