Storm Week: Tornadogenesis - KAUZ-TV: Newschannel 6 Now | Wichita Falls, TX

Storm Week: Tornadogenesis

Everyday there are scientists working to save the lives of future generations who will be faced with one of the most destructive, unpredictable and fascinating things on earth, tornadoes.  On average well over 100 of them rip through Texas each year.

Tornadoes can form within multiple types of thunderstorms, but the most significant tornadoes are usually linked to supercell thunderstorms.

For supercells, or very tense storms to form, the atmosphere has to be favorable for strong rising motion.  However, for a tornado to spin out there needs to be wind shear.  Wind shear is the change in wind speed and direction with height.  When there is a lot of wind shear, horizontal rotation can be produced.  If that horizontal rotation is flipped into the vertical rotation, it creates a rotating thunderstorm.

"The process by which these supercells create tornadoes is something we are still trying to figure out.  We understand how it is tilted into the vertical in the mid levels within a storm, or a supercell, but how that storm generates rotation near the ground that is a slightly different process that involves the downdrafts within a storm," said Dr. Christopher Nowotarski, an associate professor for the Department of Atmospheric Sciences at Texas A & M University.

A downdraft is the downward motion of wind within a storm.  The downdraft is formed by falling precipitation and evaporative cooling.  If the precipitation falls through dry air in the atmosphere small amounts of water will evaporate.  This ultimately cools the air, making it sink and strengthening the downdraft.  Once that air hits the ground it spreads out creating an outflow.

"You will have this gust of wind and it becomes colder before you get into the meat of the thunderstorm.  That change in temperature can actually produce some rotation, but we really want to do research to understand why that happens in some storms and not in other storms," said Dr. Nowotarski.

From previous field research projects, Dr. Nowotarski said meteorologists are starting to pick up on some characteristic differences between tornadic and non-tornadic storms. 

"Tornadic storms tend to have warmer outflow.  If it is too cold that air is very dense and cannot be lifted again and that extra lifting or recycling of the air within the storm maybe very important towards tornadogenesis," said Dr. Nowotarski. 

Storms that also have more moisture near the ground tend to support tornadoes as well.

If we are able to tell exactly which storms would spin up a tornado many lives could be saved.  Until that happens scientists are going to continue to study them.

"The main tools we have in the field to study tornadoes are mobile doppler radars.  In addition to understanding or measuring or how much precipitation is in the air, it can also measure the direction that precipitation is moving," said Dr. Nowotarski.

Precipitation moves because the wind blows it.  So if you know what the precipitation is doing you can figure out how the wind is acting towards or away from the radar.

"We often have mobile soundings and a sounding is taking a weather balloon and launch those in close proximity to the storm in its environment and into air that the storm is ingesting," said Dr. Nowotarski.

Meteorologists not only study tornadoes outside in the their actual environment, but inside on computer models to simulate them.

"Some people are interested in looking in at real cases.  They are looking at storms that were tornadic in the past and then trying to model that," said Dr. Nowotarski.

By modeling past tornadoes researchers can get a more complete data set of weather observations.  In the field there is holes between each weather station and the computers help fill in those gaps.

"Taking an idealized representation of what a tornadic storm or a non-tornadic storm environment is and then slowly adjusting that in different simulations to see how slight changes in the storm's environment change the characteristics of the storm itself," Dr. Nowotarski. 

Changing the models environmental conditions of a storm can help meteorologists determine what is and isn't important to tornadogenesis.

Computer power is one of the problems holding meteorologists back.  Dr. Nowotarski said the short life-span of tornadoes and their size is what makes them so hard to forecast.

One day all this research is going to payoff.  Many years from now we are going to be able to forecast an exact tornado path hours if not days in advanced.

James Parish, Skywarn 6 Meteorologist


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