Breakdown: What is a tornado emergency & how it differs from a tornado warning
MEMPHIS, Tenn. (WMC) -A tornado emergency is an enhanced version of a tornado warning according to the National Weather Service. A tornado emergency is used during significant tornado events in highly populated areas. A tornado emergency generally means that significant, widespread damage is expected to occur and a high chance of numerous fatalities is expected with a large, strong to violent tornado.
A tornado emergency is intended to convey the urgency of the weather situation the public, who are then advised to take precautions immediately if they are in the warned area. Tornado emergencies are usually identified through visual confirmation or radar confirmation of “a large and extremely dangerous tornado that is ongoing. People in the storm’s path are also advised to seek shelter in an underground shelter to stay safe from the storm, if available.
Many twisters that are larger than ¼-mile in width have produced catastrophic damage falling under the “strong” or “violent” categories (EF2–EF5) of the Enhanced Fujita Scale. However, some tornadoes of this intensity have resulted in very few to no fatalities.
With the national implementation of Impact-Based tornado warnings in 2016, common criteria were established for the use of tornado emergency. [12] National guidance requires the confirmation of a tornado via radar or spotter confirmation, with evidence the ongoing tornado is strong to violent. [17]
Before usage, the following criteria must be met according to the National Weather Service:
- A large and catastrophic tornado has been confirmed and will continue
- The tornado will have a high impact
- The tornado is expected to cause numerous fatalities.
Local offices established criteria for tornado emergencies such as:
The National Weather Service Weather Forecast Office in Jackson, Mississippi defines a tornado emergency as “an enhanced Tornado Warning that will be issued by NWS Jackson when there is a heightened risk for a killer or violent tornado of EF3 rating or greater. Their criteria for issuing a tornado emergency are:
- Radar indication of a strong tornado
- Reliable reports of significant damage or a large tornado
- Environmental conditions supportive of strong tornadoes, which is usually the case when a Particularly Dangerous Situation Tornado Watch is in effect.
The National Weather Service office in Nashville, Tennessee also created criteria to declare a tornado emergency within a tornado warning statement effective January 1, 2011. It states, “Tornado Emergency can be inserted in the third bulletin of the initial tornado warning (TOR) or in a severe weather statement (SVS).” Before the phrase can be used:
- A confirmed large tornado doing significant damage must be going through a highly populated area
- Radar must indicate tornadic debris
- The tornado must be expected to cause significant, widespread damage and loss of life.
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