Sun-Mon, Jan. 27-28th Winter Storm Update #8: Heavy snow expected late tonight into tomorrow morning across portions of Illinois

(10:00PM - 1/27/19) Our winter storm continues to slowly get its act together across the northern plains this evening and as mentioned in previous posts, it will continue southeast into the rest of the Midwest and portions of Illinois by late tonight/overnight. This will mean rapidly deteriorating conditions from west to east thanks to moderate to heavy snow and very cold temperatures, at least initially. ​

Taking a look at current radar to our west and northwest across the northern plains and into Iowa, we can see snow quickly organizing and pushing off to the southeast and east. It will continue in the direction of Illinois and Wisconsin over the next several hours as this winter storm really begins to get cranking. There is already an area of light snow out ahead of the main area that is moving through portions of northern Illinois already this evening, helping to saturate the atmosphere ahead of the main system. The area of low pressure will take a track through Iowa overnight and then through northern Illinois tomorrow morning. ​

Snow will quickly overspread all of northern Illinois by late tonight and overnight and this continues to be hit hard among high resolution model guidance this evening with a good amount of consistency and agreement. Expect continuous snow all night, possibly heavy at times overnight into the predawn hours with snowfall rates potentially reaching or exceeding 1"/hr in some locations. The loop below runs from this evening through the late afternoon and early evening hours tomorrow. The darker blues are indicative of moderate to heavy snow as strong warm air advection really helps lead to impressive snowfall rates ​

Another important aspect of this system will be the wind. High resolution model guidance (see loop below) continues to show strengthening southerly and southeasterly winds at the surface, potentially gusting over 30mph. This is going to lead to blowing and drifting snow, especially initially as snow will be more on the dry side. By the predawn hours, both temperatures aloft and at the surface will warm, making the snow more of the wet variety but still will cause big headaches for the Monday morning rush hour across all of northern Illinois. ​

As just mentioned, temperatures will warm by the early to mid morning hours across portions of northern Illinois as the surface low passes nearly overhead. This will allow temperatures to briefly warm into the upper 20's and low 30's across some of the area before cold air quickly returns from the northwest as the low passes to the east. ​

​We are continuing to monitor this evolving winter storm as it inches closer late tonight and with that, here is our latest thinking on expected snowfall accumulations across the state. This system remains just about on track so we've only made a few minor adjustments. Below is our latest TAM snowfall forecast for the winter storm.

​MP

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