Excerpt - A severe weather outbreak is likely tonight through tomorrow from the eastern Southern Plains east to the Mississippi River Valley (Southern IL southward). The models have been trending slower and slower with this system with each consecutive run, with the WRF now forecasting the dryline to cross the I-35 corridor late tomorrow (Tuesday) morning. Therefore, the severe weather threat for today will hold off until after dark when the upper-level support arrives. Beginning early tomorrow afternoon, or even late tonight, the threat for tornadoes will increase dramatically over Northeast TX, East OK, and AR as supercells become surface-based....