Abnormal Tornado Activity

[Clayton k Cross]

I was just thinking about it and I noticed that this years tornado season is not like it has been in the past recent years. In early spring the most of the storms have been in Dixie Alley and Southern Hoosier Alley, Southern Illinois and Southern Indiana. Most of the storms this year have been in the upper Midwest and through the "tornado alley" area which is usually active more towards late May and early June. Does anyone have any thoughts or answers why this trend is looking like this and what could it mean to later season activity?

 

[Evan Hawkins]

could be the fact that tornado alley is shifting towards the west?

 

[Clayton k Cross]

That could be the case, but also it is the same zone that is active right now is usually more active during later season and usually early season is super calm compared to years in the past

 

[Evan Hawkins]

could be the "global warming" everyone's talking about lol. Nah, in all reality if not the tornado alley thing, it could be the fact that one day its 80, 90 degrees out, the next its 34 degrees, but I doubt that. not sure what it is, I can do some research if you'd like

 

[Warren Faidley]

I don't have time, but there are ways to produce (or find) a semi-scientific map to illustrate this theory.

 

[Evan Hawkins]

I don't have time, but there are ways to produce (or find) a semi-scientific map to illustrate this theory.

when you do have time would you be able to share it with me?

 

[Evan Hawkins]

from the NWS:
A study published recently in npj Climate and Atmospheric Science, by Vittorio A. Gensini of Northern Illinois University and Harold E. Brooks of the National Severe Storms Laboratory, looked into the possibility that tornado frequencies are changing across the United States. Their findings include a decrease in the traditional "Tornado Alley" of the Great Plains and an increase in the Southeast's "Dixie Alley". This study generated a fair amount of buzz, so we thought we'd briefly list out a few of the more important points mentioned in the study:

• After removing non-meteorological factors, the annual frequency of U.S. tornadoes through the most reliable portions of the historical record has remained relatively constant.
• Detecting spatial shifts in tornado frequency is challenging. Tornadoes are short-lived and affect very small geographical areas. Also, tornado reporting procedures have varied dramatically over the years and from one region to another.
• The study used the Significant Tornado Parameter (STP) to account for tornado frequency. STP is designed to highlight the existence of atmospheric ingredients favoring large storms capable of producing EF2-EF5 tornadoes, like what is typically seen in the Great Plains.
• It should be noted that even if the atmosphere is supportive of tornadoes with the right winds, moisture, and instability, thunderstorms won't form without a strong enough trigger to spark them (like a cold front). The STP does not account for whether or not a trigger is present.
• However, STP values correspond with tornado reports closely enough such that STP is a suitable index to use. STP is especially useful in January, February, March, May, and December.
• The period analyzed in this study was from 1979 to 2017.
• A significant upward trend in tornado frequency was found in portions of the Southeast, Midwest, and Northeast.
• Both tornado reports and tornado environments indicate an increasing trend in portions of Mississippi, Alabama, Arkansas, Missouri, Illinois, Indiana, Tennessee, and Kentucky.
• It should be kept in mind that STP is designed to evaluate environments favorable for large storms typical of the Great Plains, and not necessarily small spin-ups that we see in regions farther east.
• Unfortunately, increases in tornado frequency in the American South juxtapose with a population that is especially vulnerable to tornadoes. The Southeast already represents a maximum in the occurrence of tornado casualties.

Keep in mind that this study was not associated with nor is it necessarily endorsed by NOAA or the National Weather Service. This information is presented here simply because of public interest.

It should be noted that this is just one study. Nevertheless, it is important for residents of the Ohio Valley and southeast United States to always be prepared for severe weather, including tornadoes. Right now, when the weather is quiet, is an excellent time to put together a tornado safety plan for your family. Have a survival kit and your plan in place well before severe weather strikes!

 

[Mike Smith]

• The STP does not account for whether or not a trigger is present.
• However, STP values correspond with tornado reports closely enough such that STP is a suitable index to use. STP is especially useful in January, February, March, May, and December.

The STP is a significant stretch to actual tornadoes. And tornadoes do occur in the months of April and June!

A more likely explanation (although it, too, has holes) is that tornado alley migrates as Ted Fujita found: There Is Nothing New About the Hypothesis Tornado Alley Has Moved East .

 

[Evan Hawkins]

I didn't know Mr. Fujita was still alive, I thought he died a while ago

 

[Mike Smith]

I didn't know Mr. Fujita was still alive, I thought he died a while ago

Sadly, he passed away in November, 1998.

 

[Evan Hawkins]

oh, ok so I was right