The Storm Prediction Center has included nearly all of our region in a high risk category for severe thunderstorms today and tonight, with a line from roughly Poplar Bluff to Carbondale and points northward still in a moderate risk.  This is a very rare situation in that the SPC only issues a high risk just a few times each year throughout the entire country.  Here is their definition of a high risk:  A HIGH risk area suggests a major severe weather outbreak is expected, with a high concentration of severe weather reports and an enhanced likelihood of extreme severe (i.e., violent tornadoes or very damaging convective wind events occurring across a large area). In a high risk, the potential exists for 20 or more tornadoes, some possibly F2 or stronger, or an extreme derecho potentially causing widespread wind damage and higher end wind gusts (80+ mph) that may result in structural damage.

Tornado Threat:.

We're expecting storms to begin firing up as early as mid afternoon, especially across NW TN and the MO Bootheel, then spread north and east across the rest of the area.  During the first part of the event, the main threat will isolated supercells, which could produce large hail and potential long-track, violent tornadoes.  With some sunshine breaking through early this afternoon, as well as temperatures in the mid-70's and dewpoints in the 60's, there is ample energy available for strong storms.  Also, the wind fields in the atmosphere are tremendously strong, and with lots of vorcity (spin) extending throughout the atmosphere, any storms that form will also spin, which enhances the tornado threat.

As we head into later tonight/overnight, a cold front will push eastward through the area, bringing an end to the threat.  But as it does, we're expecting the storms to evolve into a more organized line.  As this line of storms presses through, the main threat will shift to damaging straight-line winds, with the potential for some bowing segments to form in the line.....and that is where the threat of damaging winds and isolated tornadoes will be greatest.

This has the potential to be a widespread and significant event, and to make matter worse, the majority of the threat will be present tonight after dark.  Make sure that your weather radios are turned on and programmed properly, and also make sure to have your severe weather plan in place.  We'll be updating you on the situation all afternoon and evening, and of course, you can check us out at wpsdtv.com, our 24/7 weather channel, at 87.7 FM, and of course on NewsChannel 6.

-Meteorologist Trent Okerson