Quick-hitting tornadoes test the limits of local forecasters
Apr. 18—This week was an active one for severe weather across the Central Plains and Midwest, as not one, but two low-pressure systems swept west to east across the heartland. Each produced episodes of damaging winds and hail across parts of Northwest Missouri and Northeast Kansas — one system spawning a small outbreak of "weak" tornadoes.
The first and worst severe weather event of the week arrived on Tuesday morning, as a potent spring storm system tracked west to east across the plains. Just before 6 a.m., a supercell thunderstorm dropped a brief EF1 tornado in Osage County, Kansas, followed by a second EF1 tornado a few minutes later, which crossed into parts of Shawnee County injuring two. A tornado warning had been issued for the area when the funnels touched down southeast of Topeka, giving residents notice of the threat as it materialized.
A few hours later, two small tornadoes touched down here in the Show Me State, striking northern Nodaway County. An EF0 touched down just before 9 a.m. two miles east of Maryville, followed by an EF1 minutes later west of Hopkins, resulting in one injury. Similar to the Kansas tornadoes earlier in the morning, the Nodaway County twisters were weak and short-lived, but this time, they came without the notice of a tornado warning.
There are many factors that could have contributed to the lack of warning ahead of the Nodaway County tornadoes, something the National Weather Service works diligently to avoid. With that being said, two explanations stick out the most.
One is the type or "mode" of thunderstorm that spawned the twisters. Different from the supercell thunderstorm that dropped the Kansas tornadoes, a line of storms known as a QLCS (quasi-linear convective system) was responsible for the Nodaway County event. QLCS tornadoes are known to form quickly and without much lead time, as their rotational signature tends to be more obscure, taking the form of a "kink" within the line of storms. The more prevalent threat from QLCS-type storms is often damaging straight-line winds, which were accounted for with a severe thunderstorm warning when the tornadoes struck.
The second possible reason the Nodaway County tornadoes "flew under the radar" is literally because they flew under the radar. To expand a bit on this point, much of far Northwest and North Central Missouri lies within the outer bounds of Doppler radar coverage between Topeka, Kansas City, Omaha and Des Moines. Because Doppler radar works using a beam of radio waves that shoots at an upward angle from the ground-based instrument, radar returns are sampled from higher in the atmosphere with greater distance from the radar site. This likely played a factor in the Nodaway County instance, where rotation was most defined closer to the surface.
Another EF1 tornado spawned by a QLCS-type thunderstorm struck the Smithville Lake area just after 10 a.m. Tuesday, no injuries were sustained despite homes and a campground being significantly impacted. In this case, the National Weather Service Kansas City/Pleasant Hill office issued a tornado warning just in time, a testament to the skill and timeliness of forecasters who make it their duty to sort through the chaos behind the scenes when seconds count.
Jared Shelton can be reached at jared.shelton@newspressnow.com.
