textproduct: Columbia

WHAT HAS CHANGED

Aviation discussion updated for 12z TAFs.

KEY MESSAGES

- 1. Above normal temperatures continue today, causing an elevated risk of heat-related illness.

- 2. Thunderstorm chances increase today, a few of which could be strong. Unsettled weather continuing into the work week.

DISCUSSION

Key Message 1: Above normal temperatures continue today, causing an elevated risk of heat-related illness.

Above normal temperatures are expected to persist across the region again today as an upper-level ridge remains over the Southeast. The ridge is expected to gradually weaken over the next several days as troughing advances eastward. 850-mb temperatures are forecast near the 90th percentile Sunday ahead of an approaching front. Breezy conditions in the afternoon are expected to help mix down some lower dew points, so lowered them a few degrees from the previous forecast. Despite lowering the dew points, heat index values on Sunday are forecast to be in the 100F-105F range once again, remaining below than our Heat Advisory criteria of 108F. Additionally, increasing chances for afternoon/evening convection Sunday during peak heating should help limit max temps and reduce the duration of the most intense heat. Even though our Heat Advisory criteria is not expected to be met today, it is important to exercise caution if spending time outdoors to reduce the risk of dealing with a heat-related illness. Temperatures after today drop some due to the ridge breaking down, then hover around normal for much of the week ahead.

Key Message 2: Thunderstorm chances increase today, a few of which could be strong. Unsettled weather continuing into the work week.

The overall environment appears somewhat more favorable for organized convection for this afternoon and evening, with improved forcing and increased shear due to an approaching front. 0-6 km bulk shear values of 20-30 kt, combined with increased instability could support a few strong thunderstorms. Storm mode is expected to consist of a few linear segments and multicell clusters ahead of the front, with damaging wind gusts as the primary threat, mainly in the late afternoon and into the evening hours. After the front passes today/tonight, Monday looks to have lower coverage in showers or storms. Beyond that, persistently high IVT (90th percentile per NAEFS) should aid in keeping things unsettled through mid week. By the end of this upcoming week, it appears that another front may make it into the area & another focus for showers and storms.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

VFR conditions expected through the TAF period outside of afternoon convection.

Scattered high clouds continue over the area with another hot and humid day expected. Diurnal cumulus should develop and scattered afternoon thunderstorms expected, some possible severe. Carrying a PROB30 group for convection 18z-00z. Surface winds expected to be stronger today as the pressure gradient increases ahead of an approaching upper trough with southwesterly winds picking up to around 10-12 knots with gusts around 20 knots after 15z. Winds should subside with sunset at around 5 to 6 knots.

EXTENDED AVIATION OUTLOOK...Greater rain chances are expected early next week along with possible associated restrictions with a stalled frontal boundary.

CAE WATCHES/WARNINGS/ADVISORIES

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