The weather analysis this evening showed a low pressure system over western Kansas with a warm front stretching east from the low...along a line from near Concordia, KS, to Kirksville, MO, to near Champaign, IL. That front is expected to reach the Wisconsin/Illinois border sometime between 6 and 8 AM Tuesday morning. Warm and moist air intercepting the front will result in more shower and thunderstorms along and north of it. With the front getting to our border by morning, we expect a round of showers and storms late tonight through tomorrow morning across southern Wisconsin. Some storms may produce heavy rainfall. The threat for severe weather looks very low at this point for this round of storms. See the image below that highlights the frontal position early in the morning.
Keep an eye on thunderstorm trends here:
By late afternoon or evening on Tuesday, a weak low pressure system will have moved northeast of the area, over northern Lower Michigan. A trailing frontal boundary will likely stretch across southern Wisconsin during the late afternoon. If we see enough sunshine and increased instability, another round of showers and storm are possible. A few of these storms could be severe. See the image below, along with the Storm Prediction Center's highlight of a slight risk for severe thunderstorms.
By Wednesday, the warm front will lift north of the area and we will see temperatures climb into the lower 80s! By Thursday and Friday, the risk for thunderstorms will increase, as a strong low pressure system and its frontal boundaries begin to move into the region. There is some uncertainty as to where exactly the storms will be during this time, and if there will be a severe weather risk. Keep up with the forecast for this period. High temperatures will be in the 80s again on Thursday, and the amount of moisture in the air will increase. There are indications that a severe weather risk will exist on Friday, as a cold front moves into the area and interacts with the warm, moist and unstable airmass. See image below:
Updated by Davis