textproduct: Columbia

WHAT HAS CHANGED

Heat Advisory issued for parts of the northern and eastern Midlands. Aviation Discussion updated for 06z TAFs.

KEY MESSAGES

- 1. Above normal temperatures through the weekend will increase the risk of heat-related illness.

- 2. Isolated thunderstorms Friday; rain chances increase over the weekend into early next week.

DISCUSSION

Key Message 1: Above normal temperatures through the weekend will increase the risk of heat-related illness.

90th+ percentile upper ridging and moist low level south-southwest flow over the state will persist through the upcoming weekend. High temperatures will be in the mid to upper 90s today through Sunday with dewpoints in the mid 60s to low 70s in the afternoon. This is expected to lead to Heat Index values peaking in the low 100s with some values in the 105-108F range possible. Given this will be some of the hottest temperatures and heat indices so far in 2026, decided to issue a Heat Advisory for the northern and eastern Midlands, where most of the hottest heat indices are expected this afternoon. Although there is still low confidence we will exceed criteria (HI of 108F-112F), these early season heat waves tend to contribute to a higher risk for heat-related illness, so we are messaging extreme caution. Additionally, the experimental Heat Risk category of Major (3 out of 4) will be in place for the entire forecast area today, with even some Extreme (4 out of 4) areas starting to show up over the weekend particularly in our concrete jungles of Columbia and Augusta. Additional headlines may need to be considered for the weekend with subsequent forecast packages.

Key Message 2: Isolated thunderstorms today; rain chances increase over the weekend into early next week.

A classic summertime convective pattern will be in place for the next few days. slightly above normal atmospheric moisture and strong daytime heating will allow conditions to destabilize each afternoon through the weekend. Offshore surface high pressure and upper ridging will generally work against convective initiation and keep our overall coverage low. As such, expect isolated to scattered showers and thunderstorms each afternoon/evening, with some enhancement closer to the coast along a sea breeze. Colliding outflow boundaries will also serve as additional sources of lift and new storm initiation, particularly into the evening. This pattern could support a few stronger pulse-type cells leading to damaging downburst winds but a widespread threat is unlikely. For today, SPC has issued a Marginal Risk (1/5) for severe thunderstorms mainly north of a McCormick-Columbia-Sumter line, with a Slight risk (2/5) in the northernmost portion of Lancaster County including the Charlotte Metro.

Moisture transport then increases early next week with NAEFS IVT percentiles over 90 percent of climatology, and remain elevated through at least the middle of next week. With this in mind, expect a more active pattern with above normal moisture (and subsequently lower temperatures given the higher rain chances) to kick in by Monday and last for several days.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

VFR conditions are expected to continue through the TAF period.

Clear skies are in place across the area again this evening as earlier convection (primarily near CAE/CUB) diminished several hours ago. Surface high pressure to our southeast is continuing to maintain westerly flow across the area. Surface moisture is quite robust but shouldn't result in ground fog or restrictions through sunrise. Sunny skies should give way to cumulus again this afternoon, with isolated convection again possible. Coverage should remain limited enough to keep convection out of TAFs at this point. However, we may need a TEMPO group or two later on to account for brief restrictions associated with any convection near TAF sites. By tonight, clear skies should again return.

EXTENDED AVIATION OUTLOOK...Isolated to widely scattered diurnal showers and storms possible into this weekend. Greater rain chances are expected early next week.

CAE WATCHES/WARNINGS/ADVISORIES

SC...Heat Advisory from 11 AM this morning to 8 PM EDT this evening for SCZ016-022-029-031-038-115-116. GA...None.