Widespread severe weather is expected tomorrow from the Great Lakes region into the middle Mississippi Valley as a potent upper level trough digs into the northern Plains; a trailing cold front will sweep across the southern Plains tomorrow evening, sparking additional severe thunderstorms in Kansas and Oklahoma. Moderate to strong instability will be in place across most of Oklahoma and a large part of Missouri and central Illinois, with CAPE >1,000 J/kg stretching all the way into southern Wisconsin. Combined with strong shear, this will set the stage for what may become a large-scale severe weather outbreak.  The Storm Prediction Center has issued a Day-2 Moderate Risk for portions of Illinois and Missouri, where strong tornadoes, very large hail and widespread damaging wind will be possible. This is a developing situation and those in the "hatched" area should monitor the conditions, as a dangerous weather situation may be unfolding this time tomorrow.