AccuWeather.com

By Jillian MacMath, AccuWeather.com Staff Writer

Apr 4, 2012; 10:03 AM ET

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Ken Weathers tweeted out this damage pic from Etowah (McMinn Co.) by Josh Ault

The National Weather Service implemented an experimental tornado warning policy change to offices that serve Missouri and Kansas on Monday, April 2, 2012.

The new policy will apply three distinct sub-categories of tornado warnings, as follows: an "ordinary" tornado warning, a warning of a "particularly dangerous situation," stating that a tornado has been sighted on the ground and a "Tornado Emergency", which will explicitly state that there is a tornado on the ground and will include words such as "mass devastation and "un-survivable" when necessary.

The warnings have been implemented to effectively communicate the severity of an approaching storm, and to encourage more people to take heed.

The policy is designed to help mitigate the frequency of which people ignore alarms for impending storms, especially people living in mobile homes who may need to travel to seek suitable shelter.

The May 22, 2011 devastation of Joplin, Mo., that killed 185 people and injured over a thousand residents is being used as the prime example by the National Oceanic and Atmospheric Administration (NOAA).

According to a NOAA survey report, "the perceived frequency of siren activation in Joplin led most survey participants to become desensitized or complacent to this method of warning."

In this report, the NOAA encourages that the National Weather Service "explore evolving the warning system to better support effective decision making."

"The majority of Joplin residents did not take protective action until processing additional credible confirmation of the threat and its magnitude from a non-routine, extraordinary risk trigger," the report explains.

A sample of the new warning released by the NWS reads:

"THIS IS A PARTICULARLY DANGEROUS SITUATION.

HAZARD...DEADLY TORNADO.

SOURCE... EMERGENCY MANAGEMENT CONFIRMED LARGE AND DESTRUCTIVE TORNADO

IMPACT... COMPLETE DESTRUCTION OF ENTIRE NEIGHBORHOODS IS LIKELY. MANY WELL-BUILT HOMES AND BUSINESSES WILL BE COMPLETELY SWEPT FROM THEIR FOUNDATIONS. DEBRIS WILL BLOCK MOST ROADWAYS. MASS DEVASTATIONS IS HIGHLY LIKELY, MAKING THE AREA UNRECOGNIZABLE TO SURVIVORS. TORNADO MAY BE UN-SURVIVABLE IF SHELTER IS NOT SOUGHT BELOW GROUND LEVEL."

The experimental policy change, which will run through late fall, will be analyzed by a North Carolina research team to determine if it is suitable for expansion to other parts of the country.