A tornado watch is in effect for counties west of Springfield in Missouri and for the northwest portion of Arkansas.
Two threats tonight. First, severe supercells have developed out ahead of the cluster of stronger, better organized cells now travelling over northern Oklahoma and southern Kansas. These cells are in northeast Oklahoma and southeast Kansas. One cell in Nowata County OK has been tornado warned for about an hour with initial tornado reports west and northwest of Nowata. These storms are moving northeast at about 15-20 mph. As of this writing, the tornado warning has been dropped on this storm.
The question is how much tornadic potential will these cells hold on to as they start to approach the western tier of counties of Missouri in a few hours? The slow movement might be a blessing and a curse. The slower they go, the more the stabilizing effects of the later nighttime hours will have to take effect on these storms. But the slower movement might help them to stay on a warm front advancing northward though the area. This would serve to enhance the tornado potential. They will be eyed carefully.
The other threat is the overall formation of a larger cluster of storms into a bowing echo system which would travel toward southwest Missouri after midnight. A band of heavy rain usually forms on the northern end of such weather systems which would put southern Missouri in the heavy rain area.