Tornado Outbreak In The Heartland: One Of Winter Storm Yona’s Many Tunes

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Winter storm Yona is on the Illinois-Wisconsin border Friday morning. The severe weather is along the trailing cold front. Image by NOAA

Tornadoes are the most violent storms that occur in the earth’s atmosphere.

Winter Storm Yona caused extreme weather — including tornadoes, in 19 states on Thursday.

Yona will move northeast on Friday, and its associated cold front will move east, but is not expected to cause as many severe storms.

Tornadoes: Where And When

The first tornado of the day was an EF1 that struck at 5:30 in the morning in University City, MO, northwest of St. Louis. Tornadoes rarely reach maximum strength at that time of day, but the twister damaged 100 homes and was a forewarning of a busy afternoon and evening, weatherwise.

Tornado activity increased during the day Thursday: four tornadoes were confirmed in Texas, three in Missouri, and one in Illinois. These tornadoes touched down only briefly, and none reached the EF2 level (winds over 110 miles per hour); damage was relatively minor. Four non-life-threatening injuries were reported in Texas.

Hail And Hearty Storms: Baseballs Made Of Ice

The turbulence that derives from conditional instability in the atmosphere (a state of stability that can be turned unstable by the lifting associated with a cold front or daytime heating) can produce many kinds of weather: Tornadoes are the most formidable, but thunderstorms with frequent lightning and hail are also dangerous.

Baseball-size hail was reported in Denton, Texas, and smaller but still-dangerous golfball-size hail fell in Missouri and Illinois. Auto body shops will be busy in those areas for some time fixing broken windshields.

Flooding A Concern Due to The Yona Choo-choo

Many of the areas hit by tornadoes and hail also received up to six inches of rain, causing local flash-flooding. In the Saint Louis area and eastward into Illinois, the storms ‘trained,’ — lined up and roared down the same track. Rainfall totals mounted in their paths.

And By The Way: A Foot Of Snow

The snowy side of Winter Storm Yona has been nearly overlooked because of the tornado outbreak. More than six inches of snow fell in the Minneapolis metropolitan area, and over a foot, with snow still falling, accumulated in northern Wisconsin.

Today’s Severe Weather Outlook

As the cold front sweeps east through the deep south and Ohio valley, some thunderstorm activity, with  an outside chance of a tornado will occur, especially in the afternoon and evening when the sun’s heating adds to the instability near the cold front. However, the vertical shear (change of wind speed and/or direction with height) has diminished, and with it the chance of tornadoes. By Saturday, the front will be off the coast, trailing back through Florida where a few strong thunderstorms could flare up.

The Next Severe Weather Outbreak

Forecasts show another front moving east from the plains to the deep south Sunday and Monday. The main area of activity should be farther south than that affected by Thursday’s wild weather, so the next severe weather outbreak could be whistling Dixie.

After that, forecasts show a break of at least several days in the stormy weather, as the warm, humid air over the Gulf of Mexico is kept at bay by dry westerly winds at the surface. But stay tuned, tornado season reaches its peak in May.

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