A rotating supercell thunderstorm formed in Kimball, Nebraska, caught a ride in the jet stream that evolved into a Derecho bringing winds of over 100 miles per hour barreling to the east across several states. Tropical force winds started in Kansas in the Midwest, turning into hurricane-force winds in Illinois and Indiana, narrowly missing Indianapolis and Cincinnati, Ohio; the wind ended at the Kentucky-Tennessee border. This resulted from the remarkable heat dome now centered in the United States. Australian scientists have now named them the Dome of Doom.
From the Capital Weather Gang:
The storms formed amid a “ring of fire” pattern, which features relentless waves of severe thunderstorms cresting up and over a stubborn high-pressure “heat dome.” Excessive heat warnings blanket the lower Mississippi Valley, where triple-digit temperatures will combine with tropical humidity to push heat indexes above 115 degrees.
That heat and moisture is fueling vicious thunderstorms, which remain in the forecast through the weekend. Thursday’s qualified as a derecho, since it produced damage over a continuous track more than 400 miles long and delivered winds to hurricane force.
The derecho began as a rotating supercell thunderstorm that spawned a tornado near Kimball, Neb., on Wednesday evening. It then progressed east along the Kansas-Nebraska border, surfing jet stream winds eastward. The storms began to tap into that jet stream momentum, mixing it to the surface in the form of damaging wind gusts.
Strong winds caused the squall line to fan outward in the middle, arcing and taking on a backward-C shape. By midmorning Thursday, it began producing hurricane-force winds. Then it accelerated east, with forward speeds surpassing 65 mph. The Storm Prediction Center added a Level 4 out of 5 red zone to their severe weather outlooks around lunchtime, racing to keep abreast of the rapidly evolving forecast.
Derechos can form in May or June but are rare events. The storms thrive on heat and humidity. That is why most derechos form and wreak damage in late summer. But this year, the ocean and atmosphere heat has been extraordinary. It will only get hotter.
Derecho-Indianapolis and Cinncinati dodge a bullett.
Category two hurricane-force winds in Illinois. Category one in other areas.
- 100 mph — Good Hope, Ill.
- 100 mph — Swan Creek, Ill.
- 100 mph — Kahoka, Mo.
- 100 mph — Adrian, Ill.
- 100 mph — Scotia, Ill.
- 100 mph — Roseville, Ill.
- 90 mph — Adrian, Ill.
- 88 mph — Good Hope, Ill.
- 82 mph — Holyoke, Colo.
- 82 — Lake of the Woods, Ill.
- 80 mph — Mooar, Iowa
- 80 mph — Lerna, Ill.
- 77 mph — Vermillion, Kan.
- 77 mph — Corning, Kan.
Edit 6:08 pm--I edited the diary as I forgot to link the body of the diary; many apologies.