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 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