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Scale of threat levels

for South Central and Southeast Wisconsin
Tornado Threat
Hazard Map Threat Levels Safety & Impact
The "Tornado Hazard Map" depicts the local threat of tornadoes for specified areas.  It is largely based on the likelihood that tornadoes will occur, combined with the anticipated strength of the most intense tornado.

Tornado Threat Level

Threat Level Descriptions

Extreme

"An Extreme Threat to Life and Property from Tornadoes."

Within 12 miles of a location, an extreme likelihood (36% or greater) of tornadoes, with storms capable of minor tornado damage (damage consistent with that caused by F0 tornadoes), to complete distruction in the worst situation.  See description of tornado damage below.

High

"A High Threat to Life and Property from Tornadoes."

Within 12 miles of a location, a high likelihood (26% to 35% probability) of tornadoes, with storms capable of minor tornado damage (damage consistent with that caused by F0 tornadoes), to complete distruction in the worst situation.  See description of tornado damage below.

Moderate

"A Moderate Threat to Life and Property from Tornadoes."

Within 12 miles of a location, a moderate likelihood (16% to 25% probability) of tornadoes, with storms capable of minor tornado damage (damage consistent with that caused by F0 tornadoes), to complete distruction in the worst situation.  See description of tornado damage below.

Low

"A Low Threat to Life and Property from Tornadoes."

Within 12 miles of a location, a low likelihood (6% to 15% probability) of tornadoes, with storms capable of minor tornado damage (damage consistent with that caused by F0 tornadoes), to complete distruction in the worst situation.  See description of tornado damage below.

Very Low
"A Very Low Threat to Life and Property from Tornadoes."

Within 12 miles of a location, a very low likelihood (2% to 5% probability) of tornadoes, with storms capable of minor tornado damage (damage consistent with that caused by F0 tornadoes), to complete distruction in the worst situation.  See description of F0 tornado damage below.

Non-Threatening
"No Discernable Threat to Life and Property from Tornadoes."

Within 12 miles of a location, environmental conditions do not support tornadoes.   

Note:   By a large majority, F0 & F1 tornadoes occur more often than F2 to F5 tornadoes.

F0 Tornado Damage - Minor tornado damage; damage to chimneys, a few downed trees and power lines, large signs blown over, damaged porches and screen houses, and damaged lighter-weight outbuildings.  Tornado wind speeds of 73 mph or less. 

F1 Tornado Damage - Moderate tornado damage; mobile homes moved off foundations or overturned, roof surfaces peeled off buildings, cars blown off roads, several large trees downed and some power outages.  Tornado wind speeds of 74 mph to 112 mph. 

F2 to F5 Tornado Damage - Major tornado damage (up to complete destruction); mobile homes completely demolished, numerous large trees snapped off or totally uprooted, small debris objects (lawn mowers, smaller sections of roofs) become airborne missiles.  Increasingly larger areas of power outages.  Structural damage to sturdy buildings becomes a concern, beginning with roof and wall failures.  In the worst situations, well-constructed walls fail or are even removed.  Large debris objects (cars, larger sections of roofs) become airborne missiles causing further structural failures.  Trees debarked.  Tornado wind speeds 113 mph or greater, but in worse case situations 260 mph or greater.   

Determining Likelihood

  • NOAA's National Weather Service
  • Milwaukee/Sullivan, WI Weather Forecast Office
  • N3533 Hardscrabble Road
  • Dousman, WI 53118
  • 414-744-8000
  • Page Author: MKX Webmaster
  • Web Master's E-mail: w-mkx.webmaster@noaa.gov
  • Page last modified: 2-Nov-2005 10:23 PM UTC
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