Fri-Sat, Dec 10-11th Severe T'Storm And High Wind Event Update #3

(11:45AM - 12/10/21) A storm system moving through the region will bring severe t'storm and high wind potential to portions of the state, this afternoon through Saturday afternoon.

Summary...
A storm system will move from the Plains today on into the Great Lakes on Saturday. This storm system will bring severe t'storm potential to much of the state this afternoon through early Saturday morning, and high wind potential to much of the state tonight through Saturday afternoon.

With this update we have pulled severe t'storm probabilities a bit further north across the state once again, and have introduced a level 4/numerous severe t'storm threat across Southern Illinois. This changes was based on increasing confidence in the scenario expected to unfold. It now is looking increasing likely that this will be a significant regional severe weather event. No changes were needed to the previous high wind forecast.

​Forecast...
Severe T'Storm Potential...
A strong storm system and associated cold front will push across the state, this evening through Saturday morning. Along and ahead of this cold front, a few rounds scattered showers and t'storms will develop across Illinois, Missouri and Arkansas this afternoon into tonight. This activity will push northeastward, moving across much of the state later this afternoon and evening through early Saturday morning. Ahead of this activity, the environment across much of the state will be supportive of a severe t'storm threat. This environment will feature low instability of 500-2,000J/KG, dew points in the mid 50's to mid 60's, strong forcing, high shear and lapse rates of 5.0-7.0C. This environment will be supportive of upwards of a level 1/isolated to level 4/numerous severe t'storm risk across the state. Damaging winds, tornadoes and small hail will be the severe weather threats. Across Southern Illinois, the environment will be supportive of several tornadoes, as well as the potential for a strong and/or long track tornado.

High Wind Potential...
A storm system moving through the region today and Saturday will bring a period of high winds to a large portion of the state, tonight through Saturday afternoon. The combination of the following will lead to the period of high winds... An amplifying/phasing disturbance, strengthening/deepening storm system, strong pressure rise couplet and strengthening jet with high winds aloft. Wind gusts of 35-50MPH will be likely tonight through Saturday afternoon across much of the state.

​Below are the severe t'storm and high wind forecasts for this event.

JP