New tornado outbreaks in the Midwest

Tornado and severe weather season in the central U.S. have ramped up this spring. Last week was especially tough as at least 50 twisters were reported from the Deep South northeastward into Michigan. According to Accuweather.com, there were at least three tornadoes that hit EF3 on the Enhanced Fujita Scale. These occurred in Arkansas, Tennessee and Missouri. There were also over 200 reports of damaging hail across this region.

The worst of the outbreak occurred last Wednesday. The National Weather Service issued nearly 730 severe thunderstorm and tornado warnings. This was the third highest number of severe weather warnings since records began in 1986.

This storm system slowed down as it moved eastward late last week. As of this writing, forecasters from the National Weather Service were predicting “life-threatening floods” from Arkansas into Kentucky. Some of these areas could see as much as a foot of rain from this system.

This year has been active thus far. The strongest twister in 2025 was an EF4 that ripped through Franklin and Diaz, Ark., on March 14, then through Tylertown, Miss., on March 15.

The most intense tornadoes are rated as an EF5, which is the highest. The last time the U.S. reported a twister that strong was May 20, 2013, in Moore, Okla. One of the most devastating seasons was back in 2011 when there were multiple EF5 twisters reported. Joplin, Mo., experienced devastating tornadoes in 2011, as that event was the deadliest in the United States since 1947.

In an average year, more than 60% of all U.S. tornadoes each year occur in what is called Tornado Alley, which stretches from Texas and Oklahoma northward through Kansas and eastern Colorado into Nebraska and Iowa. The state that has the highest average number of twisters each year is Texas, with a total of 135.

The formation of tornadoes, especially in the U.S. Midwest, is the result of very unique atmospheric conditions in this region. Although the formation of tornadoes is not completely understood, the most destructive ones will form from “supercells.” If conditions are right, the rotation within the cloud will tighten. These rotating thunderstorms can then spawn a funnel cloud or tornado.

The massive systems will form strong collisions of opposing air masses. When warm, humid air from the Gulf of America (Gulf of Mexico) collides with the cooler and drier air from Canada or the Rocky Mountains, the stage will be set for those supercell thunderstorms to form. With the flat terrain in the central U.S., there is little obstruction from mountains that helps the air masses mix more easily, which can help with the development of longer-lasting storms.

Here in Idaho, the average number of twisters each year is four. The Cascade Mountains to the west and the Rockies to the east usually protect us from the extremely powerful thunderstorm activity. But every spring season, and sometimes during the hot summer months, we do see an occasional period of extreme weather conditions.

One of the worst tornados in Idaho’s history, based on damage and intensity, occurred in the Magic Valley region near Jerome and Twin Falls in the southern part of the state. On May 31, 1990, an F2 size twister damaged dozens of homes and buildings. Some agricultural equipment was destroyed, and power poles were snapped. Fortunately, there were no injuries.

On May 31, 1997, there was another F2 tornado that developed near Athol and was also listed as one of the strongest in the state. No one was injured and most of the damage was to old trees in the area.

Other F2 twisters in Idaho occurred in Power, Nez Perce, Minidoka, Madison and Bonneville counties. There was an F2 twister that was reported in Bonner County on April 9, 1991.

In terms of our local weather, the overall pattern is expected to bring occasional rainfall to the lower elevations through at least the middle of the month. There’s also the chance of thunderstorm activity, which is typical for this time of year.

During the full moon cycle that begins April 12, there’s still the possibility of some snow in the lower elevations, but mainly during the overnight hours. Based on the long-term patterns, we’ll likely end up with the current snowfall total of 36.1 inches in Coeur d’Alene, which is only 52% of the normal for the season. We had the moisture, but it was too warm for many of the storms as snow levels were generally above 3,000 feet.

As I mentioned last week, with sea-surface temperatures showing signs of warming over the next several months, we believe that April and May will have moisture totals near to above normal across the Inland Northwest. The summer of 2025 is not expected to be as hot and dry as 2024, but moisture totals are forecast to once again be below normal levels. Stay tuned.

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Contact Randy Mann at randy@longrangeweather.com.