Even though the calendar says the middle of April, Mother Nature could not care less and she is going to show why beginning tomorrow evening across portions of the state. Numerical model guidance continues to come into good agreement on a weather system bringing a swath of accumulating snow into portions of the state later Thursday into Friday morning. An update follows below...
Our system of interest has come down from British Columbia early this morning and is now moving south and southeast across the Pacific Northwest. It will then turn more to the southeast over today and tonight, eventually crossing the Rockies and emerging out in the plains by Thursday morning with a rough track shown below in blue.
As the system crosses into the plains, a widespread area of precipitation will develop north of the developing surface low across the central plains before eventually streaking eastward into the Midwest and Illinois, as shown below. Model agreement on this general scenario is quite good but there remains differences in the exact location of the swath of accumulating snow into Illinois. The animation loop below runs from 4am on Thursday to 10am on Friday morning.
Periods of moderate to heavy snow will be possible Thursday evening into Friday morning across portions of northern and central Illinois as things stand now. Not surprisingly given it's mid-April, temperatures will be marginal, thus meaning the greatest snowfall accumulation will be on colder surfaces. The favorable thing going for this event is that the snow will be falling mostly at night and overnight, allowing for maximum accumulating potential vs the snow falling during the day. This can mean a big difference in mid-late April regarding snow accumulations.
We will continue to ride with this current thinking for expected snowfall totals for now but this is subject to change over the next 36 hours ahead of this incoming system so stay tuned for further updates.