In general, it’s about 10 to 15 minutes now. The lead time for warnings has also improved. About 87% of deadly tornadoes from 2003 to 2017 had an advance warning. The percentage of tornadoes that trigger a warning has increased over recent decades, due to Doppler radar, improved modeling and better understanding of the storm environment. What radar showed as a tornado headed toward Rolling Fork, Mississippi, on March 24, 2023. Those offer more clues that a storm is likely to produce a significant tornado. Some research suggests that a wider mesocyclone is more likely to create a stronger, longer-lasting tornado than other storms.įorecasters also look at the storm’s environmental conditions – temperature, humidity and wind shear. If you have a supercell on radar and it has strong rotation above the ground, that’s often a precursor to a tornado. The vast majority of violent tornadoes form from supercells, thunderstorms with a deep rotating updraft, called a “mesocyclone.” Vertical wind shear can enable the midlevels of the storm to rotate, and upward suction from this mesocyclone can intensify the rotation within the storm’s outflow into a tornado. How far in advance can you know if a tornado is likely to be large and powerful? The characteristics of that cold air outflow are important to whether a tornado can form, because tornadoes typically form in that cooler portion of the storm. If you’ve ever been in a thunderstorm, you know that right before it starts to rain, you often get a gust of cold air surging out from the storm. How wind shear interacts with rain-cooled air within storms, which we call “outflow,” and how much precipitation evaporates can influence whether a tornado forms. One of the strongest predictors of whether a thunderstorm produces a tornado relates to vertical wind shear, which is how the wind changes direction or speed with height in the atmosphere. One way scientists gather data for understanding tornadoes is by chasing storms. These small changes in the storm environment can have large impacts on the processes within storms that can make or break a tornado. Even changes in the land surface conditions – fields, forested regions or urban environments – could affect whether a tornado forms. The differences between them could be due to small differences in meteorological variables that aren’t resolved by our current observing networks or computer models.

Often, you’ll have a line of thunderstorms in an environment that looks favorable for tornadoes, and one storm might produce a tornado but the others don’t. But predicting exactly which thunderstorms will produce a tornado and when is harder, and that’s where a lot of severe weather research is focused today. Meteorologists have gotten a lot better at forecasting the conditions that make tornadoes more likely. Why are tornadoes still so difficult to forecast? Chris Nowotarski, an atmospheric scientist, explains why, and how forecast technology is improving. But pinpointing exactly where a tornado will touch down – like the tornadoes that hit Rolling Fork, Mississippi, on March 24, and towns in Arkansas, Illinois and multiple other states on March 31 – still relies heavily on seeing the storms developing on radar. At one point, more than 28 million people were under a tornado watch.

Meteorologists began warning about severe weather with the potential for tornadoes several days before storms tore across the Southeast and the Central U.S.

United states doppler radar