Severe Thunderstorms

A Severe Thunderstorm Is . . .

National Weather Service (NWS) Defines:

A Severe Thunderstorm:

One that 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

Thunderstorms may occur singly

In Clusters

In Lines

Thunderstorms

Some of the most severe weather occurs when a single thunderstorm affects one location for an extended time.

Risks Posed by Thunderstorms

Lightning Hail Downbursts and straight-line winds Flash floods Tornadoes

Lightning

Most victims of lightning strikes survive

75 – 100 people are killed each year in U.S.

$ 5 Billion economic loss each year. In U.S.

HAIL

Hail can be as small as a tear drop or as large as a softball

Can cause damage to automobiles, glass, roofs, plants and crops

Pets and livestock are particularly vulnerable

Winds

Thunderstorms can produce winds up to 150 mph

Strong enough to flip cars, vans, trucks and do damage to structures

Flash Floods

Heavy rain from Thunderstorms can cause flash flooding

Flash Flood – A sudden rise in water

Tornado

Some severe thunderstorms can cause tornadoes

Severe Thunderstorms

The National Weather Service (NWS) issues watches and warnings

What is a Thunderstorm Watch and Warning?

Thunderstorm Watch

A watch is issued when severe thunderstorms are possible in and near the watch area.

People should be alert for approaching storms!

Thunderstorm Warning

A warning is issued when severe weather has been reported by spotters or indicated by radar.

You are within striking distance. 6-10 miles

Warnings indicate imminent danger to life a property

Severe Thunderstorms

How are Warning and Watches issued?

Warning & Watches

National Weather Service (NWS) will issue Warning and Watches over EAS (Emergency Alert System)

Varies in areas, TV & Radios

Sirens

Lightning

Lightning often strikes outside areas of heavy rain

Lightning strikes can occur as far as 10 miles

People are in danger if you can hear the thunder!

50 % of lightning deaths occur after the storm passes

Lightning

NWS 30/30 Rule

If the times delay between seeing lightning and hearing thunder is less than 30 seconds, there is a risk of lightning strike.

Stay indoors after hearing the last clap of thunder.

Question?

How can you prepare for a severe thunderstorm?

Thunderstorm Preparedness

Understand the Risk Can occur anytime!

Know your Area!

SW Florida – Lightning Capital of the World

Thunderstorm Preparedness

Learn to make a small target Squat low to the

ground, making the smallest target while minimizing ground contact.

Thunderstorm Preparedness

Pay attention to warnings EAS and 30/30 Rule Never Ignore

Warnings

Question?

What should you avoid doing during a severe thunderstorm?

During a Thunderstorm

Avoid: Water sources.

If Boating or swimming, get to land. Stay away from water and wet sand

Stay away from running water

During a Thunderstorm

Avoid: The telephone and appliances.

Stay off phone line and computers – Lightning can travel through wires and cables.

Don’t use appliances Surge protectors do not stop lightning

During a Thunderstorm

Avoid: The outdoors.

Go inside a sturdy structure

If You Are Outdoors . . .

Get away from water sources. Seek shelter in a substantial building. If necessary:

Take shelter in a car or. Go to low-lying area and make a small target.

Avoid natural lightning rods.

Severe Thunderstorms

What should you do if you are caught driving in a severe storm?

Driving in Severe Thunderstorm

Pull safely to side of road. Away from trees or other tall objects.

Avoid contact with metal objects. Don’t lean on inside metal of car

Avoid flooded roadways. Flash flooding may occur

Question?

What should you do following a severe thunderstorm?

After the storm

Listen to EAS – additional warning or inaccessible areas

Avoid storm damaged areas – damaged structures and possible flooding

Watch for fallen power lines and trees – report immediately