textproduct: Columbia

WHAT HAS CHANGED

Minor adjustments made to key message, hot and mainly dry conditions are expected this afternoon and on Thursday with heat index values as high as 105 degrees. Aviation discussion updated for 18z TAFs.

KEY MESSAGES

- 1. Hot conditions continue across the area, with limited chances for thunderstorms this afternoon and on Thursday. Higher chances of rain return this weekend with a slow moving front.

DISCUSSION

Key Message 1: Hot conditions continue across the area, with limited chances for thunderstorms this afternoon and on Thursday. Higher chances of rain return this weekend with a slow moving front.

Latest 500mb analysis shows a mid-level ridge axis centered across the eastern forecast area this afternoon. This feature, combined with stable conditions in the 700-500mb layer, suggests that any thunderstorm coverage this afternoon will be isolated in nature. Any convection that does form should struggle to have significant vertical development therefore the threat for strong to severe thunderstorms is low but non-zero given the ample CAPE and DCAPE available. Based on current satellite imagery, it appears southern and eastern portions of the CWA would be most likely to see isolated showers and thunderstorms and this is reflected in the PoP forecast. In terms of the heat threat for today, MaxT was bumped down by a few degrees in most spots based on current trends in the observations, but values should still top out in the mid-90s with a few spots in the upper 90s. Heat Index values will generally be between 100 and 105 degrees.

The aforementioned trough over the lower Mississippi Valley is expected to move eastward tomorrow and lift northward around the ridge over the area. As it does, the latest guidance stretches it out some. So, while the chances for thunderstorms are a bit higher tomorrow due to this, they do remain on the low side (up to ~20%) suggesting similar weather conditions to today. The latest model guidance for Friday suggests a higher risk for thunderstorms, mainly across the northern and western counties. An approaching front for the weekend brings a greater chance for shower and thunderstorm activity to the region. Flow aloft is also forecast to become more zonal, which could lead to the front and associated precipitation chances lingering into next week.

As has been emphasized over the past week, the ongoing heat remains a concern. Temperatures are expected to remain 3-6 degrees above normal through Saturday, with heat indices reaching the low to mid-100s. Most locations should remain below Heat Advisory criteria (108F), so no Heat Advisories are anticipated at this time. Continue to practice heat safety, especially with prolonged heat expected to persist. Please remain diligent if you have outdoor activities planned.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

VFR conditions expected through the TAF period.

VFR conditions in place at all the terminals with cumulus clouds developing around 5kft this afternoon. Latest satellite observations shows these clouds are remaining flat as the upper ridge is over the area with limited upscale growth expected through the afternoon. While isolated storms remain possible, probability remains around 10 percent or less for impacts to the terminals with upper ridging over the area. Westerly winds with gusts between 15 to 20 knots expected through the afternoon with winds becoming light tonight and diminishing cumulus clouds. Breezy westerly winds expected once again tomorrow with convection not expected through 18z.

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

CAE WATCHES/WARNINGS/ADVISORIES

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