Temperatures over the weekend warmed back into the low to mid 60s, right where they should for mid-April. But the chill will once again return during the first half of the work week following a rather strong cold front Monday morning.
Skies turned partly to mostly cloudy Sunday as a weak disturbance passed to the south. A few light rain showers developed as a result, but with a dry air mass in place those showers had a hard time reaching the surface, producing only a few sprinkles or brief light rain showers. Skies will turn partly cloudy following sunset before filling back in with cloud cover, becoming mostly cloudy, overnight. Those clouds will be ahead of a cold front that is expected to move through Monday morning. Behind the front lies a much cooler air mass which will bring temperatures back down below average for the beginning of the week.
Winds will then shift around to the west and northwest Monday holding high temperatures in the low 50s. A light shower or two will be possible around daybreak Monday, with lightly scattered rain showers throughout the morning and afternoon, especially south of Rockford. The cold front will quickly pass into southern Illinois Monday night and Tuesday morning, pushing highs in the low 40s Tuesday.
Another disturbance lifting up from the southwest will ride along the cold front, moving into central and southern Illinois Tuesday afternoon. Moisture pulling up from the south will interact with the cold air mass in place bringing a slight chance for light snow, or at least a light rain/snow mix, to portions of the area as early as Tuesday morning. As it stands right now, the most likely location to receive accumulating snow – a couple of slushy inches on both grassy and road surfaces – looks to be from central Illinois back west towards the Plains. Further north, while some light snow could come down, at this point doesn’t look like it will amount to much more than an inch – and mostly on grassy/elevated surfaces.
By Wednesday another weak low will be moving through which will bring a few light rain showers, possibly mixed in with a few snow flurries, to parts of the Stateline during the afternoon. Highs on Wednesday will only warm into the mid 40s.