Tuesday is shaping up to be one of the more concerning severe weather days we’ve seen in quite some time across the Foothills and western North Carolina. While scattered summertime thunderstorms are common this time of year, tomorrow’s setup is much different. The atmosphere will be unusually favorable for organized severe thunderstorms capable of producing widespread damaging winds, large hail, and locally dangerous conditions.

The greatest concern will be between 2 PM and 8 PM Tuesday, when a cold front sweeps east across the region. Ahead of that front, hot and humid air will build across the Foothills and Piedmont, providing the fuel storms need to rapidly intensify. At the same time, much stronger winds higher in the atmosphere will create an environment capable of supporting well-organized thunderstorms rather than the typical hit-or-miss afternoon storms we often experience in late July.

Why Tomorrow Is Different

Several ingredients are expected to come together Tuesday afternoon that we look for when forecasting more significant severe weather.

The atmosphere will become extremely unstable as temperatures climb into the lower and middle 90s with heat index values pushing into the upper 90s and lower 100s. At the same time, wind speeds will increase dramatically with height, creating enough wind shear to organize thunderstorms into long-lived supercells and organized storm clusters.

This combination of very high instability and 30 to 40 knots of deep-layer wind shear is not something we see very often during the middle of summer. When these ingredients overlap, thunderstorms become much more efficient at producing severe weather.

Main Threats

Damaging Wind Gusts

This is expected to be the primary hazard. Thunderstorms could produce wind gusts over 60 mph capable of bringing down trees, causing scattered power outages, and producing damage to roofs and other structures.

Large Hail

Unlike most summertime storms that produce only pea or dime-sized hail, tomorrow’s stronger storms may generate hail as large as golf balls. The stronger rotating updrafts expected within some storms will allow hailstones to grow much larger before falling to the ground.

Heavy Rain and Frequent Lightning

While storms should move faster than recent flooding events, any thunderstorm will still produce torrential rainfall and dangerous cloud-to-ground lightning.

****One Important Uncertainty****

There is one factor we’ll be watching closely Tuesday morning.

A cluster of thunderstorms may move through the area during the overnight and early morning hours. If extensive cloud cover lingers well into the afternoon, it could limit daytime heating and reduce how unstable the atmosphere becomes. That would lower the overall severe weather threat somewhat.

However, if skies recover during late morning or early afternoon, the atmosphere should become primed for rapid thunderstorm development. Even with some morning clouds, enough instability may still develop for severe storms.

Greatest Areas of Concern

At this time, the highest confidence for severe weather includes:

• The North Carolina mountains
• The Foothills
• Western and central Piedmont of North Carolina
• Northern portions of the South Carolina Upstate

Our Foothills Weather Network coverage area sits squarely within the region where the ingredients appear most favorable for severe thunderstorms.

Timing

• Morning: Warm and increasingly humid with the possibility of leftover clouds or a few showers.
• Early Afternoon (2 PM): Thunderstorms begin developing.
• Mid to Late Afternoon (2 PM – 8 PM): Highest risk for severe weather.
• Evening: Storms move east as the cold front pushes through.

Be Ready Before Storms Develop

Tomorrow is not the day to rely solely on outdoor warning sirens or social media for severe weather information.

Make sure you have multiple ways to receive warnings, including Wireless Emergency Alerts on your phone, NOAA Weather Radio, trusted weather apps, and local media. If a Severe Thunderstorm Warning is issued for your location, move indoors immediately and stay away from windows until the storm passes.

Looking Ahead

The good news is this active pattern will not last long. Behind Tuesday’s cold front, much drier air arrives Wednesday through Friday, bringing noticeably lower humidity, cooler temperatures, and a welcome break from the oppressive heat. High temperatures will return to near seasonal levels before another chance of showers and thunderstorms develops over the upcoming weekend.