Severe weather is possible across far southern/southeastern Illinois later this evening. The overall threat is low, but some damaging winds and/or a couple of tornadoes will be possible. Thunderstorms are expected to develop and continue moving east/northeast across the Middle Mississippi Valley into southern Illinois by the afternoon. The Storm Prediction Center has an enhanced risk of severe weather for portions of the region, and a slight risk across our state. The tornado risk [pictured to the left] is far greater just south of our local area.
At 2:30 P.M. we notice a wide area of showers and thunderstorms moving north-northeast across the Middle Mississippi Valley. Severe weather is occurring south and west of the state with damaging winds and a couple of tornadoes. The environment down there is far more conducive for severe weather than up in our state. You can see the photo above the numerical values are dew point temperatures. A very moist air mass characterized with dew points in the 60’s and near 70 support more than enough “juice” for thunderstorm development and maintenance. Outside of the severe weather risk, we will certainly see some thunderstorms and heavy rain. Flooding is going to be a major concern for portions of southern Illinois going through the next 48 hours.
One of the reasons why severe weather is not higher across our state is due to the expansive cloud cover [above, left] which is limiting instability [above, right]. Thunderstorms will be likely due to the amount of MUCAPE [among other factors, pictured below], but surface based severe weather will not be likely for areas of central or northern Illinois.
The main concern tonight for local weather will be the extremely heavy rains that areas along and south of I-70. Several inches of rain are likely which will further cause hydro issues. Severe weather aside, the flooding this region should receive will likely steal the head lines going forward. Please remember your flash flooding protocols and most importantly to turn around; don’t drown when coming across flooded roadways.
Overall, we are expecting a low end severe weather threat across primarily: Jackson, Williamson, Saline, Gallatin, Hardin, Pope, Massac, Pulaski, Alexander, Union, and Johnson Counties. This would include: Vienna, Harrisburg, Marion, Golconda, and Jonesboro. Isolated damaging winds and a few tornadoes could be possible after 6 P.M.