Threats & Emergencies

Thunderstorms

Thunderstorm Basics • Responding to Thunderstorms

Though thunderstorms can occur anytime, they are most common in the summer months, during the late afternoon and evening hours.
The National Weather Service considers a thunderstorm severe if it produces hail at least three-quarters of an inch in diameter, has winds of 58 miles per hour or higher or produces a tornado.
Thunderstorms always include lightning and might also produce large hail and violent downbursts of rain.
Be alert to the signs of changing weather, including darkening skies, a sudden wind shift and drop in temperature. Thunderstorms can develop in less than half an hour.
The NWS does not issue warnings for ordinary thunderstorms, but they do highlight the potential for those conditions in their local forecasts and statements.
When your daily weather forecast calls for the possibility of thunderstorms, stay tuned to your local radio or television station for updated weather reports, or listen to a NOAA weather radio for more detailed information.

A severe thunderstorm watch means that conditions are favorable for the formation of a severe thunderstorm.

A severe thunderstorm warning means that a severe thunderstorm has been sighted or has been indicated on NWS Doppler radar.

Close windows and doors.
Listen to a battery-operated radio, NOAA Weather Radio or television for the latest storm information.
Do not handle any electrical or telephone equipment.
Avoid bathtubs, water faucets and sinks. Metal pipes can conduct electricity.
Stay inside until 30 minutes have passed since the last clap of thunder.

Try to get to a building or car.
If no structure is nearby, go to an open space.
Squat low to the ground, making yourself as small as possible. Do not lie flat on the ground.
Be aware of the potential for flooding.
Avoid tall structures, such as towers, telephone poles, fences and power lines.
Stay away from rivers, lakes or other bodies of water.

Pull onto the shoulder of the road away from trees that could fall on the vehicle.
Stay in the car with the windows up and turn on the hazard lights until the heavy rains subside.
Avoid touching any metal in the car.
Avoid flooded roadways.
Drive only if necessary.

A person who has been struck by lightning does not carry an electrical charge that can shock others.
Call emergency medical assistance immediately.
Check the victim for injuries.
If the victim is burned, provide first aid. Look for burns where lightning entered and exited the body.
If the person’s heart and breathing have stopped, give cardiopulmonary resuscitation (if trained to do so) until medical professionals arrive.

When it’s safe to do so, take photos of any damage to your organization’s property for use in filing insurance claims.
Report downed utility wires.