Tornadoes cause destruction in Nebraska and Iowa

Large, destructive tornadoes tore through eastern Nebraska and southwest Iowa Friday afternoon and evening, part of a multiday outbreak of severe storms expected to continue through the weekend.

Becky Kern, warning coordinating meteorologist with the National Weather Service in Omaha, said the first tornado report came in at 2:43 p.m., and twisters have since caused widespread and extensive damage.

Omaha Police Chief Todd Schmaderer said few injuries were reported. Two people in Omaha were transported to a hospital with injuries, he said.

At 3:41 p.m. local time, the Weather Service declared a tornado emergency for a “confirmed large and destructive tornado” near Elkhorn, just a few miles west of Omaha. “This is a PARTICULARLY DANGEROUS SITUATION. TAKE COVER NOW!,” the Weather Service warned.

At 3:51 p.m., the emergency warning was extended into Bennington, about seven miles to the northeast.

About 50 miles southwest of Omaha, the Lancaster County Sheriff’s Office said that at around 3 p.m. deputies went to a plastics manufacturer near Lincoln in response to a building being hit by a tornado. Upon arriving, they found the building had collapsed and several people were trapped inside. They evacuated the building, and three people were taken to the hospital with non-life-threatening injuries. About 70 employees were inside when the tornado hit.

At 4:15 p.m., the tornado emergency was extended to areas near the border with Iowa. The large twister was moving to the northeast at 30 mph into southwest Iowa. “Considerable damage to homes, businesses, and vehicles is likely and complete destruction is possible,” the Weather Service warned.

As the violent tornado swept into southwest Iowa over the next hour, the Weather Service declared additional tornado emergencies, including for Harlan and Minden where storm-chaser video revealed a massive wedge-shaped funnel. Storm chaser footage revealed severe damage in Minden.

Around this time, a separate tornado was also spotted at Omaha’s Eppley Airfield, which was closed at 5:37 p.m. One passenger obtained footage of the twister through the window of a plane on the airport’s tarmac.

The arcing band of rotating thunderstorms was expected to swing from Omaha to Des Moines into the evening and could extend as far south as Kansas City. All three major cities are encapsulated in a Level 3 out of 5 risk of severe weather drawn by the Weather Service’s Storm Prediction Center. The agency warns that “all hazards will be possible, including tornadoes with some potentially strong, very large hail over two inches in diameter, and wind damage.”

On Saturday, storms will be more widespread, with at least some risk of severe weather from northern Michigan to the Texas-Mexico border. A tornado is possible anywhere within that zone, but the risk is highest between roughly Kansas and Dallas, including Oklahoma City and Wichita, where a few intense tornadoes could form.

The active pattern doesn’t look to ease until the middle of next week, and even that is not a guarantee. Small disturbances in the jet stream could trigger additional rounds of storms, albeit more localized, over the Plains next week.

Friday’s storms

Zone 1 - Corn Belt and Missouri Valley

A Level 3 enhanced risk of severe weather covers northeastern Nebraska, southwestern Iowa, northeastern Kansas and northwestern Missouri. Omaha and Lincoln in Nebraska and Kansas City and St. Joseph in Missouri are within this zone. That is where the greatest potential for a strong tornado or two exists.

Storms will fire during the afternoon on the leading edge of a dry slot, or a wedge of cool, dry air filtering in on the backside of a low-pressure system in Nebraska. Ahead of that low, warm, humid air will waft north. The insurgence of dry air will kick that moisture upward into storms. Given proximity to the surface low, meanwhile, the atmosphere will be replete with spin.

It is expected that a band of rotating storms will form around midafternoon near or west of Omaha, then travel east along Interstate 80 toward Des Moines before weakening. Thunderstorm coverage may decrease as one heads south, but a few rotating south with an attendant tornado risk are possible all the way to Kansas City.

Storms will weaken by about 10 p.m. in eastern areas as they outrun the instability, or storm fuel, that gave rise to them.

Zone 2 - South of Kansas City to around Dallas

In this zone, storms may not be as widespread because the rising air required to incite them will be more concentrated to the north. However, a cold front trailing through the area could trigger scattered severe storms. The Storm Prediction Center warns that some storms will be “capable of all severe hazards, including very large hail and strong tornadoes.”

There are some signs that storms could be more numerous in Texas, including around Dallas, than originally anticipated. While spin won’t be overly impressive, plentiful storm fuel could foster clusters of storms capable of producing large hail, tornadoes and damaging winds. Those storms could fire as early as 1 p.m. Central time.

Looking ahead

A second storm system is already brewing in the wake of the first, and some meteorologists expect it to be stronger. A low-pressure system will garner strength in eastern Colorado and will eject onto the Plains on Saturday.

Southerly winds ahead of it will rapidly scoop warm and moist air northward. That will help the atmosphere to reload, with a return of thunderstorm fuel in some cases just 12 to 18 hours after Friday’s storms depart.

The low will also drag a dry line eastward, where storms are expected to erupt in the afternoon. Storms that sprout will probably grow tall enough to begin to rotate because of a strong jet stream roaring overhead.

A limiting factor may be morning storms. If they prove widespread, they could gobble up some of the storm fuel that otherwise would have been utilized by stronger afternoon storms. Likewise, morning storms would cut back on sunshine. Sunshine is integral to heating the ground and helping cook up more storm fuel.

Nonetheless, the Storm Prediction Center has outlined a Level 3 risk of severe weather from Des Moines all the way south to Highway 287 northwest of Dallas on Saturday. Kansas City, Wichita, Tulsa and Oklahoma City are in that zone.

“The greatest threat is currently anticipated across parts of the central and southern Plains, where very large hail, damaging winds, and a few strong tornadoes will be possible,” the center wrote. “A larger area of potential threat will extend from south-central Texas north-northeastward into the Great Lakes.”

More storms are expected Sunday, but the timing and placement remain uncertain and depend heavily on how Saturday’s storms evolve. For now, expect scattered severe storms with the potential for damaging winds and hail from the Corn Belt to East Texas.