Spotter Information Page

Current Severe Weather Information

Reference Information

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Reference Information 

What makes a thunderstorm severe?

A severe thunderstorm is a thunderstorm that produces...

  • wind gusts of at least 58 mph (50 knots), and/or
  • hail at least 1 inch diameter (quarter size) and/or
  • a tornado

  Hail Size Chart: (diameter in inches) (visual chart)

  • Pea Size: 0.25 inches
  • Small Marble: 0.50 inches
  • Penny: 0.75 inches 
  • Nickel: 0.88 inches
  • Quarter: 1.00 inches <--Any hail this size or larger is severe thunderstorm criteria
  • Half Dollar: 1.25 inches
  • Ping Pong Ball: 1.50
  • Golf Ball: 1.75 inches
  • Hen Egg: 2.00 inches
  • Tennis Ball: 2.50 inches
  • Baseball: 2.75 inches
  • Grapefruit: 4.00 inches
  • Softball: 4.50 inches

Wind Speed Estimate:

  • 25-31 mph: Large branches in motion; whistling heard in telephone wires.
  • 32-38 mph: Whole trees in motion; inconveniencefelt walking against the wind.
  • 39-54 mph: Twigs break off trees; wind generally impedes progress.
  • 55-72 mph: Damage to chimneys and TV antennas; pushes over shallow rooted trees.
  • 73-112 mph: Peels surfaces off roofs; windows broken; light mobile homes pushed or overturned; moving cars pushed off road.
  • 113-157 mph: Roofs torn off houses; cars lifted off ground.



 Spotter Training Classes

Frequently Asked Questions about Spotter Training Sessions

  1. Do I need to preregister for these sessions? No. All you need to do is arrive at the proper time and location.

  2. About how long do the sessions last? Approximately 2 hours.

  3. Do I have to live / be a spotter in the county that I take the training session? No. The training sessions are identical.
  4. Is there online training I can review after attending the training course? Yes. You can find the online training at:

Below is a listing of upcoming severe weather spotter training sessions.


April, 2014 - Upcoming
Day City, State Time Location
17 Seymour, IN
(Jackson County)
6:30pm EDT Main Source Bank, 1130 E. Tipton St
19 Spencer, IN
(Owen County)
9:00am EDT Spencer Christian Church, Montgomery & Market St
19 Brazil, IN
(Clay County)
1:00pm EDT Library, 204 N. Walnut St
29 Switz City, IN
(Greene County)
6:30pm EDT Extension office (4H fairground), Highway 54 is the U.S. government's official web portal to all federal, state and local government web resources and services.