Saturday, June 20th, marks the official first day of summer with the summer solstice occurring 4:43 PM CDT on Saturday. This means Saturday is also the “longest day” of the year when the city of Rockford will receive 15 hours, 16 minutes, and 26 seconds on sunlight. Unfortunately, the Stateline won’t see too much of that sunlight with cloudy skies and a good amount of rainfall in the forecast.
Through Friday, a stationary front had parked itself over central Iowa bringing plenty of rain and a several thunderstorms to the eastern half of the state. The rain failed to sustain itself long enough to stretch very far into the Stateline due to a much drier lower and middle atmosphere. Although, as the front slowly inches eastward and approaches the Mississippi, conditions will become more suitable for the rain here in northern Illinois. Rain chances are expected to gradually increase through the overnight and into Saturday morning. The rain coverage will become more widespread as the morning transitions into the afternoon. A localized low pressure system embedded within the front will strengthen through the day and begin to propagate northeastward into southern Wisconsin by midday. The front will then reorganize into a cold front as it picks up speed and is dragged across northern Illinois through the second half of Saturday. This will allow for the development of scattered thunderstorms across the region from the midafternoon through most of the evening. A few storms may be on the stronger side with brief heavy downpours and strong gusts accompanying them. The greatest probability for stronger thunderstorms occurs from the early to middle evening. As of Friday evening, the Storm Prediction Center has a marginal risk for severe weather over the Stateline for Saturday.
The rain will gradually taper off overnight and into Sunday morning. There is a chance of waking up to a few light, spotty showers on Sunday but by late morning, just about all the rain should as a plume of dry air moves over trailing the cold front. Skies should clear up to partly cloudy by the afternoon. Therefore, we’re expecting a good amount of sunshine and little to no rain for most of Father’s Day. Another system moving in from the west will likely bring some showers back to the Stateline overnight. This system of low pressure will push across northern Iowa and move through southern Wisconsin through the day on Monday. This will result in widespread rain for most of Monday with a good chance for a few embedded thunderstorms as well before conditions mostly dry out for much of the upcoming week.