Big changes coming to tornado warnings

There's no severe weather threat today, but April 1st is the start of a new way of doing things when it comes to the way tornado warnings are issued.

From now on, when the National Weather Service issues a tornado warning, they will use a new approach called "impact based warnings".

The change came about after intensive study of the Joplin, Missouri tornado on May 27, 2011 which killed more than 150 people there.  Research found that most people only took cover after verifying that there was an actual threat from a tornado on the ground and did not heed initial weather service warnings.

The new approach is designed to communicate more clearly and more precisely what and how severe the tornado threat is.

For example, tornado warnings will be tagged with the likely damage threat, with the terms  "considerable" or "catastrophic" used.

"Possible" will be used in severe thunderstorm warnings when a thunderstorm has the possibility of producing a tornado, but confidence is not high enough to issue a tornado warning.

Tornado warnings will begin to use the phrases such as "Considerable" when a tornado is likely on the ground and will cause significant damage, and "Catastrophic" will be used rarely and only when a large tornado is occurring and will almost certainly cause major damage, such as the Joplin tornado.

"Radar indicated" and "observed" will also be used when tornado warnings are issued to differentiate between when a storm could spawn a tornado and one that is and has been observed by spotters or other strong evidence, such as a debris ball showing up on radar.

Impact based warnings will also spell out specific calls of action that the public should take to protect property and lives.