A high risk for severe weather is in place for the Midwest this evening as a life-threatening severe weather outbreak unfolds. Meteorologists issued the highest risk possible as they are now expecting a derecho, or a dangerous line of thunderstorms that produces destructive hurricane-force winds over hundreds of miles.
The Storm Prediction Center is calling for a 60% chance for damaging winds in excess of 75 MPH, which is the highest category of damaging winds they issue and is only reserved for derechos. This means that the threat for intense damaging winds is 60 times higher than one would normally see on any given day.
At 3:45PM CDT, the line of storms in eastern Nebraska is rapidly organizing into a bow echo, with winds exceeding 100 MPH just 1,500 feet above ground level. The downdrafts in the thunderstorms could easily translate these winds to the surface.
The left image shows precipitation while the right image shows the winds within the storms.
Most meteorologists try to use the term "derecho" sparingly because it can cause people to panic, so the fact that the Storm Prediction Center uses the word three times in their latest forecast indicates a high confidence in the potential for this type of violent windstorm.
This is a life-threatening situation for those in the path of the severe storms today. If you know someone who lives in the area or if you live there yourself, please make sure that all loose items outside are secured or brought inside now before the storms threaten. The derecho will approach fast and hit with a sudden fury rather than gradually building up like storms normally do. Make sure you are in a sturdy building away from windows and tall trees when the storm hits.
It's worth mentioning that the threat for tornadoes still exists, especially over Nebraska and Kansas where the potential for rotation is the highest. The SPC is maintaining a 10 times higher-than-normal risk for significant (EF-2 or stronger) tornadoes across these areas.
If you live in the areas threatened by severe weather, please keep a close watch on the weather today as conditions can change with little notice. You can follow severe weather forecasts with the Storm Prediction Center, and view the latest warnings and local forecasts from your local National Weather Service office. The best (free) radar imagery for you load online is offered on Wunderground's website.
[Images via SPC and Gibson Ridge]