Tornado Threat Expanded Across All of Western North Carolina Today. Ensure Wireless Emergeny Alerts Are Enabled on Cell Phones

The severe weather threat has increased across our area this afternoon and evening. The Storm Prediction Center has expanded the tornado risk to include all of western North Carolina, the northern South Carolina Upstate, and extreme northeast Georgia.

Damaging winds and large hail remain the primary threats, but the environment will also support an isolated tornado risk. This does not mean widespread tornadoes are expected. It means a storm that remains isolated and develops persistent rotation could produce a tornado with relatively little warning.

The atmosphere will be complicated today. A cluster of storms approaching from Kentucky, West Virginia, and northeast Tennessee will bring clouds and possibly a few showers or storms into the region this morning. What happens with that activity will play an important role in how the afternoon unfolds.

If clouds and morning storms linger and keep temperatures down, they could reduce the amount of instability available later today. However, if the atmosphere can recover and we get several hours of heating, conditions could become increasingly favorable for organized severe thunderstorms by late afternoon. A few western areas received roughly an hour of heating this morning, though the sun angle was lower, and it did not amount to a significant amount of heating.

We could see surface-based instability climb into the 2,000–4,000 J/kg range while winds strengthen and turn with height. Deep-layer wind shear may exceed 40 knots, which is more than enough to organize storms and support rotating supercells. That combination is why the tornado threat has been expanded.

Storms farther east across the Piedmont—including areas toward Charlotte—may have a better opportunity to remain discrete. A discrete storm is one that stays separated from surrounding storms, allowing it to pull in warm, unstable air without interference. Those storms would have the greatest potential to produce very large hail, damaging winds, and an isolated tornado.

Across the foothills and mountains, storms may organize more quickly into broken lines or clusters as the cold front approaches. That could lower the tornado potential somewhat, but rotating structures may still become embedded within those lines. Damaging straight-line winds would be the primary concern in this part of the area, although large hail and an isolated tornado will remain possible.

Some of the strongest storms may produce:

• Damaging wind gusts capable of bringing down trees and power lines
• Large hail, potentially approaching two inches in diameter in the most intense storms
• Frequent lightning and torrential rainfall
• An isolated tornado, especially with any storm that remains separated and develops persistent rotation

The most likely window for severe weather appears to be from midafternoon through this evening, although we will be watching the morning activity closely. The exact timing and coverage will depend heavily on how quickly the atmosphere recovers behind the early clouds and storms.

It will also be extremely hot and humid ahead of the front. Temperatures should reach the lower and middle 90s east of the mountains, with heat-index values generally in the upper 90s to lower 100s. Parts of northeast Georgia and the western South Carolina Upstate could experience heat indices between 105 and 108 degrees.

Today is not a day to rely only on an outdoor warning siren. Make sure Wireless Emergency Alerts are enabled on your phone and have another dependable way to receive warnings. If a warning is issued, move immediately into a small interior room on the lowest floor of a sturdy building, away from windows.

We will be watching radar, satellite trends, surface observations, and the recovery of the atmosphere throughout the day. Any clearing and rapid temperature increase behind the morning activity would be an important sign that the afternoon severe threat is becoming more likely.

Once the cold front moves through, much more comfortable weather arrives. Wednesday through Friday will be less humid, mainly dry, and cooler. Temperatures could turn even cooler this weekend, although shower and thunderstorm chances are expected to return.