Tornado Alley does not live up to its name with near record silent activity in April


Not even a dozen tornadoes were reported in Texas, Oklahoma, Kansas and Nebraska during the month of April. This is only 16% of all preliminary April tornadoes in the United States, down from the average of 28%. Only 2018 has seen weaker tornado activity since 2000, according to the Storm Prediction Center database.

This part of the country has generally not seen many tornadoes so far this year either. In the second week of May, 60 tornadoes were reported, compared to the 2012-2021 average of 80 tornadoes. Most of these tornadoes were reported in Texas and produced by only a few storm systems.

Tornado Alley encompasses much of the central plains. The region of Texas in South Dakota is where the frequency of tornadoes is highest, especially from April to June.

Tornado alley is generally a common area for tornado formation.

This is where storm systems form when air passes over the Rocky Mountains and the ingredients necessary for tornadoes to develop meet. This includes strong and variable winds in the upper levels of the atmosphere, warm temperatures at ground level, and high humidity flowing north of the Gulf of Mexico.

“The decline in tornado activity was largely the result of an unfavorable tornado pattern with sometimes strong cold fronts diverting the deep, rich, high-quality moisture from the Gulf of Mexico to the south of the region. Says Matt Elliott, coordinating warning meteorologist with the National Oceanic and Atmospheric Administration’s Storm Prediction Center.

The entire country experienced a relatively calm April in terms of tornado activity this year, with 63 reports, which is below the average of 192 preliminary tornadoes. The state with the most tornadoes was Louisiana.

Tornadoes are most common in the Southeast, such as Louisiana, Mississippi, Alabama, and Georgia, during the first half of the year. From April, the risk of activity shifts to the plains, or tornado alley, and becomes very likely there.

Indeed, these areas are usually the first to receive the warm, humid spring air – and since the plains have been colder than normal, we did not see this humid air mass spread much to the surface. ‘outside the southeast so far this year.

The majority of this year’s tornado reports have been in the south

But those four southeastern states reported 26 tornadoes in April, more than Tornado Alley’s 10. Last year, that difference was even more dramatic when 195 tornadoes were reported in those southern states, compared to 42 in the southern plains.
Here's why the United States has more tornadoes than any other country

“This year, the persistent weather pattern which has been generally unfavorable to severe storms on the plains has been more favorable for the southeast,” Elliott told CNN.

Aside from tornado counting, the number of tornado watches issued and their placement by the Storm Prediction Center illustrate where forecasters believed to be the best chance of thunderstorms producing tornadoes.

Most of the watches issued so far this year have been issued in Mississippi, Alabama, Tennessee and Georgia, while Kansas, where several watches are expected to be issued, do had only one.

Climate change could move tornadoes southeast

Global warming could move tornadoes to the densely populated southeast.

Several studies, including a 2018 study by Victor Gensini and Harold Brooks, a researcher at NOAA’s Severe Storms Lab, have observed a significant increase in southeast tornadoes and tornado environments since 1979. They also noted a significant increase in southeastern tornadoes and tornado environments since 1979. downward trend of tornadoes in the more traditional tornado aisle. ‘of the great plains.

“While there is one big thing to take away from future tornadoes, it looks like overall they are going to become more frequent, especially in the southeastern United States,” said Gensini of Northern Illinois University. .

His research has shown that severe storms and tornadoes will become more frequent east of the Mississippi River as the climate warms.

This spring’s tornado data aligns with that science for tornado reduction in Tornado Alley, although the frequent outbreaks of cold air this spring are likely the biggest culprit.

Ocean temperatures could be to blame

Another hypothesis of this low activity is the ocean temperature in the Pacific Ocean. La Niña is the phenomenon involving the long-term cooling of sea surface temperatures near the equator.

The current sea surface temperature is deviating from normal, highlighting cooler-than-normal temperatures in most of the equatorial waters of the Pacific Ocean.
Some years when there is a strong La Niña, this could impact the increase in tornado activity, such as in 2011 when Oklahoma and Texas had a 100 tornadoes in April.

But not all events are the same, says Elliott: “While strong La Niña years may offer a little greater potential for more tornado activity, it certainly doesn’t guarantee it.”

A La Niña is currently present in the Pacific, according to the Climate Prediction Center, but tornado activity has been dismal on the plains this year.

Don’t count Tornado Alley yet

The weather can change drastically in an instant. Even though tornado activity this spring has been rather calm in the plains, a change in weather patterns can trigger a tornado outbreak and even increase activity to above-average levels in a single day.

In 2010, Oklahoma only experienced a few tornadoes in early May, but 53 tornadoes affected the state in a single day, according to coordinating meteorologist of alerts Rick Smith at the National Weather Service office in Norman, Oklahoma.

It is important to stay abreast of weather conditions and monitor the weather forecast throughout the year for any changes in this pattern.

“We are now entering (or soon will be for Nebraska) peak tornado season in these areas, so it is important to be alert when thunderstorms are forecast and to be prepared to take action if threatening weather conditions occur.” are approaching your area, ”says Elliott.

Cooler-than-normal temperatures in the eastern two-thirds of the country this week are expected to keep extreme weather conditions to a minimum in most of the United States. Highs will be up to 30 degrees below average in the southern plains on Wednesday.

Forecast of temperature deviations from normal Wednesday.

Warmer temperatures are expected to gradually return by this weekend, which could increase the chances of intense thunderstorms, including tornadoes.

CNN’s Judson Jones contributed to this report.


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