EXPLAINED: A team is surveying the damage in Onalaska. This is how they will classify the tornado.

National Weather Service in Onalaska Surveying Damage After an Extremely Destructive Tornado on April 22nd. Here is a Deeper Look at how Tornadoes are Classified.

Enhanced Fujita Scale measures intensity of tornadoes.

The National Weather Service is sending a small survey team to survey the damage in Onalaska where at least 20 people were injured and three people were killed after a tornado ripped through multiple neighborhoods on Wednesday evening.

Tornadoes are different animals

Southeast Texas is very familiar with hurricanes. Days before the storm we watch the monster storms ramp up from a Category 1 storm to a Category 5.

Residents prepare for a storm with a rough idea of the strength of the hurricane. This also gives the public time to make their communities as safe as possible.

Tornadoes are different animals. Although we know in advance that conditions are prime and residents should listen for possible warnings the touch down of a confirmed tornado happens quickly and the duration of the storm is short compared to a hurricane.

This leaves little time for folks that could be in the sometimes unpredictable path of a tornado to seek shelter. With such a short time frame tornadoes are not classified ahead of time but rather are classified by the damage they left behind.

After a tornado rips through a town evidence is left behind that a trained team of meteorologists decode to determine how strong a tornado actually was. A piece of sheet metal wrapped around a tree, a car tossed like a toy even a home that is half way untouched and completely flattened on the other side give meteorologists information on how strong a tornado’s winds were.

What a survey team does

The survey team is tasked with decoding the tornado’s life cycle. Where did it start? Did the tornado stay on the ground or make multiple touch downs? How long did it last? How wide and long was the damage path? All of theses questions are important for classifying the tornado.

When all the evidence is collected the survey team matches the damage they see to what wind speed is required to produce that damage and classify the tornado using the Enhanced Fujita Scale.

Enhanced Fujita Scale measures intensity of tornadoes.

About Southeast Texas destructive tornadoes

Southeast Texas is not know for large destructive tornadoes.

We typically encounter EF0 to EF2 tornadoes. An EFO tornado would cause minor tree damage, maybe damage to gutters while an EF2 would could cause significant roof damage. EF5 tornadoes are the most destructive where homes are completely flattened leaving only foundations left behind. An EF5 has never been recorded in Southeast Texas and EF4 tornadoes are historic and very rare. One rare EF4 tornado was recorded in Galveston on September 12 1961 during Hurricane Carla.