(11:45AM - 12/31/21) A winter storm is expected to move through the region on Saturday. This winter storm is expected to produce a swath of accumulating snow across the northern half of the state.
A storm system will move from the Plains on Saturday morning, through the Mid-Mississippi Valley and Ohio Valley Saturday afternoon into Saturday night, and then into the Northeast by Sunday morning. This storm system is expected to bring a swath of accumulating snow across the northern half of the state, Saturday morning through Sunday morning. Additionally, lake enhancement/lake effect snow will be likely across Northeast Illinois during this time as well.
With this update no significant changes were needed, as the going forecast looks good based on current information. At this time there continues to be some disagreement within model guidance, which will be resolved in the next 18 to 24 hours leading up to the winter storm. Stay tuned for future updates.
Precipitation is expected to spread northeastward across Northern and Central Illinois Saturday morning. Across the northern half of the state, precipitation is expected be be all snow for the duration of this winter storm. Snow is expected across the northern half of the state from the onset Saturday morning, through Saturday afternoon and evening, before ending with time Saturday night or early Sunday morning. Snow will be moderate to heavy at times, with snowfall rates up to or in excess of 1" per hour at times, especially Saturday afternoon and evening. Lake enhanced/lake effect snow will also be possible across Northeast Illinois, which could add to snowfall totals for that area. Additionally, wind gusts of 20-40MPH can be expected as well, which could cause some blowing and drifting of snow.
Further south across Central Illinois, while portions of the area may stay as all snow for the duration of the winter storm, a transition zone is likely to set up across Central Illinois. Along this transition zone; a mix of snow, sleet, freezing rain and rain will be possible. Minor accumulations of each wintry precipitation type will be possible. Even further south across the southern half of the state, precipitation will come in the form of rain and t'storms...However, at this time no severe weather threat is expected.
Snowfall totals upwards of 2-5" to 4-7" are expected across much of the northern half of the state. Across Central Illinois, where the wintry precipitation transition zone will set-up, snowfall totals may vary greatly over short distances and be nonuniform...As well as there being the potential or minor freezing rain and sleet accumulation.
Below is the snowfall forecast for this winter storm.