Slow Moving Systems

High pressure is sitting over the western end of the Upper Peninsula of Michigan this evening while low pressure is over Kansas with a warm front stretching into southwestern Missouri. A dying thunderstorm complex is moving across southern Illinois, while a new one develops over southeast Iowa and northeast Missouri, but it is being directed toward the southeast by the northwest flow across the area.  All the Stateline will get from this system will be some high thin blow off tops that have thinned out into cirrus clouds that will allow filtered starshine for the ovenight hours. The high pressure to our north will dominate weather through the overnight hours with high cirrus clouds and cool temperatures. The high pressure will slowly begin to ease off to the east as a Greenland block in the mid and upper atmosphere starts to weaken. That will allow the weather system over the southern and central plains to slowly move toward the east and northeast. So, it will become mostly cloudy on Tuesday with a slight chance of showers in the morning. By afternoon there may be enough instability for a thunderstorm or two to develop. On Tuesday night and Wednesday the system will advance into Illinois giving the area a good chance of showers and thunderstorms.