Ask Heather - must have been a tornado?

KNOXVILLE, Tenn. (WVLT) -- Almost every time our region has storm damage, some think it must have been a tornado. Heather explains why a severe storm is something to pay attention to.

A light breeze can make a hot day comfortable, but a strong wind can cause damage.

When the National Weather Service assesses storm damage, there are several things they look for to determine if it was a tornado or straight-line wind damage, severe thunderstorm.

The direction(s) the of debris and damage, indicates if there was rotation. It's not the extent of damage. Meaning, major damage doesn't mean it had to be a tornado.

The threshold for the NWS to issue a severe thunderstorm warning is wind speeds of more than 57 miles per hour, and/or hail that's at least 1 inch. The hail and the wind speeds can cause damage, along with lightning and heavy rain.

Tornado damage is rated on an Enhance Fujita Scale, 0 to 5. The lowest tornado rating means the wind gusts are estimated to have been at least 65 miles per hour. They also have damage indicators based on the stability of the structure.

EF Scale:
http://www.spc.noaa.gov/faq/tornado/ef-scale.html

What I hope you'll see here is that the wind speeds are strong and potentially dangerous, when a tornado warning is issued AND when a severe thunderstorm warning is issued. Damage is possible under both warnings, and you should take cover when either one is issued.

Here are examples of wording from NWS warnings:

Severe Thunderstorm Warning:

FOR YOUR PROTECTION...MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE INTO AREAS WHERE WATER COVERS THE ROAD.

Tornado Warning:

TAKE COVER NOW. MOVE TO A BASEMENT OR AN INTERIOR ROOM ON THE LOWEST FLOOR OF A STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME OR OUTDOORS... MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT YOURSELF FROM FLYING DEBRIS.


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