Favorable area for severe thunderstorm development is the triple point of the surface low, warm front, and dry line. Numerical models typically forecast limited precipitation with a large upper level ridge to the west of the forecast area. However, short waves, especially at 500 mb come off the front side of the ridge and produce large clusters of thunderstorms. 500 mb flow over the geographical midpoint is 280 degrees or greater. Troughs approaching the apex of the upper level ridge from 600- 400 mb.
Optimum time is late afternoon to early morning hours.
Outbreaks usually last 8 to 10 hours. This includes damaging winds, large hail, and tornadoes, but the most pronounced feature is torrential rainfall. Since heavy rain and flash flooding is the biggest culprit of these enormous features, an in depth discussion will not be included. Additional reading should include Rochette et al.