All the ingredients are coming together for a severe weather outbreak this afternoon and evening.
Tornadoes, hail, wind and flash flooding are all possibilities, but damaging winds are far and away the biggest threat.
Winds in the upper levels of the atmosphere are clipping along above the states of Nebraska, Iowa, Missouri and western Illinois. These strong, upper-level winds paired with the proper ingredients at the surface are the makings of a widespread severe wind event, possibly a derecho.
Forecast models are showing especially high probabilities for derecho development over southern Nebraska by this afternoon.
On radar, these events looks like a large bow echo, or multiple smaller bow echoes along a larger arc.
A derecho, by definition, is a large severe wind event. The damage must extend for more than 240 miles, include wind gusts of at least 58 miles per hour along most of its length, and several gusts of 75 mph or more.
These are large events covering multiple states and usually do more damage than most single tornadoes.
Luckily, this type of severe weather doesn't occur often. The criteria is so specific, it's difficult to meet all of them.
The last derecho in the U.S. hit almost a year ago, affecting states from Minnesota and Iowa all the way to New Jersey.
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