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Quick Forecast Check (Southern Middle Tennessee)

We’re continuing a stretch of warm, spring-like weather across Southern Middle Tennessee. Highs today and Wednesday will run 15–20 degrees above normal, with many locations climbing into the upper 60s and low 70s. Skies stay mostly dry today, but rain and storm chances increase Wednesday night into Thursday as a cold front approaches.

A few thunderstorms are possible Wednesday night and again Thursday afternoon and evening. While the overall severe risk remains low, gusty winds and lightning will be the primary concerns with any storms that develop. The best chance for any stronger storms will be north of our area along Interstate 40.

Today’s Severe Weather Awareness Topic: Lightning

Lightning is often underestimated, but it is one of the leading weather-related killers in the United States. You don’t need a tornado or damaging winds for lightning to be deadly. Understanding how lightning forms (and how far it can strike) is key to staying safe. Our region sees frequent thunderstorms, especially in spring and summer. Lightning doesn’t need a severe warning to be dangerous. Many lightning injuries happen on “just a stormy day” when people don’t think the threat is serious!

How Lightning Forms (The Science)

Thunderstorms begin when warm, moist air rises rapidly into the atmosphere. As this air rises, it cools and forms a tall storm cloud. Strong updrafts inside the storm allow the cloud to grow vertically.

Inside the storm, ice crystals, hail, and water droplets collide. These collisions cause electrons to be knocked loose, beginning the process of electrical separation.

As collisions continue:

Negative charges collect near the bottom of the cloud
Positive charges gather near the top
The ground below the storm becomes positively charged

This sets up a powerful electrical imbalance.

When the difference in charge becomes strong enough, electricity looks for a way to equalize.

A lightning strike occurs when a stepped leader from the cloud meets a positive charge rising from the ground, producing the bright flash we see. This process happens in milliseconds, but the energy released is immense.

Why Lightning Is So Dangerous

Lightning can heat the surrounding air to around 50,000°F, which is hotter than the surface of the Sun. This rapid heating causes explosive expansion of air, which we hear as thunder.

Lightning can:

Strike miles away from the parent storm
Travel through metal, plumbing, and wiring
Occur before rain starts or after storms appear to weaken

Lightning Safety Rules That Save Lives

When thunder roars, go indoors.
If you can hear thunder, you are close enough to be struck.
Stay indoors for at least 30 minutes after the last thunder.

Get out of lakes, rivers, pools, and creeks immediately

Avoid wet areas, metal fences, poles, and bridges
Never shelter under trees or open structures

If You’re Indoors:

Avoid using corded electronics
Stay away from plumbing (sinks, showers, washing machines)
Lightning can travel through wiring and pipes

The Bottom Line 🧾

• Lightning can strike miles away from a storm
• Thunder means you are within striking distance
• Lightning is hotter than the surface of the Sun
• Stay away from water, metal, and open areas
• When thunder roars, go indoors — every time

📰 This week is Tennessee Severe Weather Awareness Week. Each day, we will focus on a different hazard that impacts Southern Middle Tennessee, with practical information to help you stay prepared and informed. The Southern Tennessee Weather Blog, presented by Heritage South Community Credit Union, is updated daily with local forecasts and safety information you can trust.

Severe Weather Awareness 2026: Lightning