Weather System Hits The Midwest Tuesday
I am analyzing the storm system that will impact the Midwest on 28 October 2014 at 1500 UTC.
At 500 mb, there is a vorticity maximum in northern Wisconsin. Plus, there is strong negative vorticity advection over Minnesota and over southern Wisconsin and northern Illinois. There is also slight positive vorticity advection between the strong negative vorticity advection areas that have been mentioned. The height gradients are huge as well. They go from 5430 meters at the vorticity maximum to 5700 meters over southern Indiana as of the 27 October 2014 1200 UTC run by the GFS003 model.
The areas of strong negative vorticity advection by the thermal wind are evident across the Midwest. In areas of negative vorticity, there is cold air advection at 850 mb. It is vice versa for areas of positive vorticity advection.
Forcing will occur in areas of negative vorticity advection and cold air advection. Therefore, negative values of omega will be evident in those areas.