An interesting set of case studies revolve around this type of zonal flow and the 1925 (Tri-State), 1965 (Palm Sunday), 1974 (Super) and 2011 (Southern States) tornado outbreaks.
At this time, the dynamics appear to be in proper place for another late March/early April significant event. To John's point...very limited polar maritime intrusion allowing for enhanced Gulf air returns into the Midwest and northeast areas of the country, with little in the way of mixing.