2006 Spotter Training Class Schedule
How To Become a Skywarn Spotter
If you are interested in becoming a Trained Skywarn Spotter ask your local Skywarn Chapter, Amateur Radio Group, or local National Weather Service Office, on how to become a member. Some organizations may require an Amateur Radio License to join. Please keep in mind that Weather Spotting can be a dangerous activity. Weather Spotting is not 'chasing'. Skywarn is a volunteer community service organization.
Severe Weather Reporting Criteria
 Tornadoes, Debris Clouds, or Funnels Aloft.
Wall Clouds (Especially if Rotation is
Present).
Hail 3/4 Inch or Larger.
Winds Greater than 58 MPH.
Rain Fall Greater than 1 Inch Per Hour
Measured.
 Flooding Which Poses a Hazard.
Wind or Other Storm Damage to Buildings,
Crops, etc.
Hail Accumulations Which pose a Hazard
or cause flooding.
Hail Size and Diameter
| Hail Diameter
| Size Description
|
|---|
| 1/4" | Pea Size
|
| 1/2" | Marble Size
|
| 3/4" (Severe Criteria)
| Dime Size |
| 7/8" | Nickel Size
|
| 1" | Quarter Size
|
| 1 1/4" | Half Dollar Size
|
| 1 1/2" | Walnut or Ping Pong Ball Size
|
| 1 3/4" | Golf Ball Size
|
| 2" | Hen Egg Size
|
| 2 1/2" | Tennis Ball Size
|
| 2 3/4" | Baseball Size
|
| 3" | Teacup Size
|
| 4" | Grapefruit Size
|
| 4 1/2" | Softball Size
|
Wind Speed Estimates and Descriptors
| Wind Speed Estimate
| Description |
|---|
| 25-31 mph | Large branches in motion;
whistling heard in telephone wires
|
| 32-38 mph | Whole trees in motion;
inconvenience felt 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
|
The Fujita Scale
| F-Scale Number |
Intensity Phrase |
Wind Speed |
Type of Damage Done |
|---|
| F0 |
Gale tornado |
40-72 mph |
Some damage to chimneys; breaks branches off trees; pushes over shallow-rooted trees; damages sign boards. |
| F1 |
Moderate tornado |
73-112 mph |
The lower limit is the beginning of hurricane wind speed; peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off the roads; attached garages may be destroyed. |
| F2 |
Significant tornado |
113-157 mph |
Considerable damage. Roofs torn off frame houses; mobile homes demolished; boxcars pushed over; large trees snapped or uprooted; light object missiles generated. |
| F3 |
Severe tornado |
158-206 mph |
Roof and some walls torn off well constructed houses; trains overturned; most trees in forest uprooted |
| F4 |
Devastating tornado |
207-260 mph> |
Well-constructed houses leveled; structures with weak foundations blown off some distance; cars thrown and large missiles generated. |
| F5 |
Incredible tornado |
261-318 mph |
Strong frame houses lifted off foundations and carried considerable distances to disintegrate; automobile sized missiles fly through the air in excess of 100 meters; trees debarked; steel re-inforced concrete structures badly damaged. |
| F6 |
Inconceivable tornado |
319-379 mph |
These winds are very unlikely. The small area of damage they might produce would probably not be recognizable along with the mess produced by F4 and F5 wind that would surround the F6 winds. Missiles, such as cars and refrigerators would do serious secondary damage that could not be directly identified as F6 damage. If this level is ever achieved, evidence for it might only be found in some manner of ground swirl pattern, for it may never be identifiable through engineering studies |
NOTE: The Fujita Scale is based on damage, not
the appearance of the funnel.
Spotter Guides and Weather Glossaries.
NOAA Storm Spotters Guide
NOAA Comprehensive Glossary Of Weather Terms For Storm Spotters.
The Weather Channel - Glossary of Weather Terms
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