Mon-Wed, April 6-8th Severe T'Storm Threat Update #3

(12:00PM - 4/7/20) Multiple disturbances will move through the region through Wednesday, bringing a daily chance of severe t'storms to the state.

Monday morning - Monday night recap...
Scattered showers and isolated t'storms occurred across portions of Northern Illinois Monday afternoon and evening, near a warm front that lifted northward into Northern Illinois through the day. As a main disturbance moved through the area, additional scattered showers and t'storms developed and spread across Northern Illinois Tuesday night...some of which were strong, producing small hail.

This afternoon - tonight...
Isolated to scattered showers and t'storms are expected to develop in the vicinity of a advancing cold front later this afternoon...across Southern/Eastern Wisconsin, Northern Illinois and Eastern Iowa. This activity will then sweep southeastward across Northern and portions of Central Illinois, from late this afternoon into early tonight. An environment featuring low to moderate instability, decent moisture, decent forcing and decent shear will be in place. This will help support a minimal to limited severe t'storm threat across Northern and portions of Central Illinois. Large hail and damaging winds will be the main threats, though an isolated tornado cannot be ruled out.It should be noted that there is a spread among model guidance regarding possible scenarios for today...Ranging from little in the way of t'storm/severe potential, with stronger capping in place, to more widespread t'storm/severe potential. However, given a good chunk of consistent guidance favoring a more active scenario and a favorable t'storm/severe environment in place, we have held steadfast through updates with a minimal to limited severe t'storm threat for aforementioned areas...But will note there is some potential for a dry frontal passage should the other solutions come to fruition.

It is possible that some activity may also back-build and develop along the cold front down into Central/Southern Illinois and Missouri, which would then push across Central and Southern Illinois this evening into tonight. However, this scenario is highly in question given stronger capping in place with southward extent... Thus, will maintain general t'storm area and a conditional minimal severe t'storm risk, as the environment will be favorable for the potential for a few severe t'storms, should t'storms develop.

Wednesday morning - Wednesday night...
Areas of showers and t'storms will be ongoing across Iowa and vicinity Wednesday morning into afternoon, associated with the next disturbance moving through the region. Additional scattered showers and t'storms are expected to develop in the vicinity of a advancing cold front, from Iowa down into Missouri Wednesday afternoon. This activity will then sweep eastward across Central and Southern Illinois, from Wednesday afternoon into Wednesday night. An environment featuring low to moderate instability, mediocre moisture, good forcing and good shear will be in place. This will help support a minimal to limited severe t'storm threat across much of Central and Southern. Large hail and damaging winds will be the main threats, though an isolated tornado cannot be ruled out.

Below is the severe t'storm forecasts for this afternoon - tonight and Wednesday morning - Wednesday night.

​JP

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