Hazard Map Threat Levels Safety & Impact
Graphical Hazardous Weather Outlook
Tornado Threat


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

  • Threat: An extreme threat to life and property.
  • Minimum Action: Preparations should be made for a very high likelihood (or a 45% probability or greater) of tornadoes; many tornadoes (even families) possible with scattered tornadoes of F2 to F5 intensity also possible.
  • Potential Impact: The potential for scattered locations to experience major tornado damage (see below), among many locations of minor to moderate tornado damage. Some tornadoes may have longer damage tracks

High

  • Threat: A high threat to life and property.
  • Minimum Action: Preparations should be made for a high likelihood (or a 30 to 44% probability) of tornadoes; scattered tornadoes possible with isolated tornadoes of F2 to F5 intensity also possible.
  • Potential Impact: The potential for isolated locations to experience major tornado damage (see below), among scattered locations of minor to moderate tornado damage. Some tornadoes may have longer damage tracks.

Moderate

  • Threat: A moderate threat to life and property.
  • Minimum Action: Preparations should be made for a moderate likelihood (or a 15 to 29% probability) of tornadoes; many tornadoes (even families) of F0 to F1 intensity possible.
  • Potential Impact: The potential for many locations to experience minor to moderate tornado damage (see below). Some tornadoes may have longer damage tracks.

Low

  • Threat: A low threat to life and property.
  • Minimum Action: Preparations should be made for a low likelihood (or a 5 to 14% probability) of tornadoes; scattered tornadoes of F0 to F1 intensity possible.
  • Potential Impact: The potential for scattered locations to experience minor to moderate tornado damage (see below).
Very Low
  • Threat: A very low threat to life and property.
  • Minimum Action: Preparations should be made for a very low likelihood (or a 2 to 4% probability) of tornadoes; isolated tornadoes of F0 to F1 intensity possible.
  • Potential Impact: The potential for isolated locations to experience minor to moderate tornado damage (see below).
Non-Threatening
  • Threat: No discernible threat to life and property.
  • Minimum Action: Listen for forecast changes; review tornado safety rules.
  • Potential Impact: None expected; strong wind gusts may still occur.
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


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