Extremely unstable air has built up again on the northern periphery of a heat wave affecting the Midwest and Plains. High wind shear will combine with the instability to produce a significant severe storm risk. Storms are already developing over Nebraska and will expand quickly northeast towards the Upper Midwest this evening.
Storms in a similar location and environment on Thursday produced hail up to three inches (7.5 cm) in diameter, damaging wind gusts to 80 mph (130 kph) and several tornadoes. Similar hazards are likely with the strongest cells this evening. After midnight, the severe storm threat should slowly diminish, although a localized strong wind threat could persist well into Sunday morning as the storms approach the western Great Lakes.
