Apr 04 | Climate Review and Weather Forecast

The transition from March to April brought very active weather in Illinois. Average temperatures this week ranged from the low 40s in northern Illinois to the low 60s in southern Illinois, between 2 and 8 degrees above normal. March ended between 2 and 4 degrees warmer than normal as well, which helped accelerate bloom and leafoutacross the state.

The big story this week, though, was the active storm track that brought multiple rounds – and multiple types – of severe weather across the state. The first round came on Sunday as storms brought strong wind, hail, and a couple of confirmed tornadoes across central and south-central Illinois. This included an EF-1 tornado that caused significant damage in southern Champaign County. Quick aside: there were 58 tornado warnings issued across Illinois last month, which is the highest number on record for March. Not to be outdone, April began with its own round of severe weather on Wednesday, including multiple confirmed tornadoes and dozens of reports of wind damage and 1-2” hail across central and southern Illinois. One of the stronger tornadoes caused significant damage and a few injuries in Bond County, and Logan County emergency management reported estimated 90 mph wind gusts on Wednesday evening, and corresponding damage to trees, homes, and power lines.

Perhaps the largest threat from this week’s weather is the flooding from very heavy rainfall in southern Illinois. As of Friday morning, most areas south of Interstate 64 have received at least 2 inches, with totals approaching 5 inches closer to the Ohio River. Unfortunately, more is to come. The southern half of the state is expected to pick up an additional 2 to 6 inches of rain between Friday morning and Sunday morning, with some parts of far southern Illinois possibly getting an additional 8 inches of rain. Flash flooding will be an immediate threat in parts of southern Illinois, and most rivers in the area are expected to rise above flood stage. In fact, the Mississippi River at Memphis is expected to rise over 25 feet between Friday morning and Monday morning, illustrating just how much water is falling across the mid-South right now.

So that’s the bad news, more rain and imminent flooding in southern Illinois. However, some good news comes next week as the entire region moves into a much drier weather pattern. A solid 5 to 7 days with little to no precipitation next week will be much welcomed to help the state dry out. That said, the dry weather will also usher in cooler air, as overnight temperatures between Monday night and Tuesday morning are expected to dip below freezing across the state, and may get down to the high 20s as far south as St. Louis and the low 20s in much of northern Illinois.