Discussion: A Tornado Watch was in effect for Northern Missouri until midnight September 21st. This watch was issued at 6:25 P.M. CDT September 20th due to a small cluster of thunderstorms with embedded supercell structures moving into Northern Missouri, these strong to severe storms created the threat for a few tornadoes, isolated damaging wind gusts, and isolated large hail. The watch area is smaller than usual, though this can be attributed to the cells being small in both size and quantity.
As of 7:28 CDT September 20th, only a single supercell remained, tracking south-southwest close to an axis of strong instability in Northern Missouri. The focus for lift (one of the important factors for thunderstorms thunderstorms) isn’t very strong, but adequate enough for the storm to linger for a little while longer before the boundary layer starts to stabilize. At approximately 10:50 P.M. September 20th, the Tornado Watch was allowed to expire, as the storm which prompted the watch and warnings, had weakened below severe limits. Interesting to note was the unusual south-southwesterly direction of the storm, since most storms in the Northern Hemisphere move east or northeast due to the Coriolis effect deflecting objects (in this case, wind) from left to right, or west to east.
At this time it is important to take a moment to show some appreciation to the National Weather Service for informing the public of severe weather through its system of watches and warnings. It is also a good opportunity to encourage the public to continue to heed watches and warnings when issued, as these watches and warnings can save lives.