The long advertised storm from last week will finally move over the Chicago metro area during the next 24 hours. This system has been tracked since my first article last Wednesday. Really amazing the long range computer models (ECMWF) can forecast these large systems so far out in time. Compare today's graphic of the surface low valid Friday at 6:00 a.m. CST compared to 7 days ago, same model. Considering we are looking at computer output over a week out, pretty darn close in my opinion.
The system has slowed down a little compared to earlier speeds. The result is a slower moving surface low pressure system. What this means for the metro area is a longer period of some freezing drizzle, or mixed very light snow and freezing drizzle from late tonight to roughly midday Friday. A slower moving low pressure means a longer wait for the above freezing surface temperatures to move in. The freezing drizzle will add a little glaze on top of any surface that is not treated.
It looks like the snow will spread over the metro area from southwest to northeast from roughly 9:00 p.m. - midnight CST. The southwest suburbs around 9:00 p.m., O'Hare 10:00 p.m., and the toward the Wisconsin border toward midnight. Snowfall amounts will range from 1-3 inches far southeast to a general 3-5 inches, heaviest southwest. For our snow deprived winter so far, this will be the largest snow for south and central sections. Far north sections had up to 7 inches last week.
When one considers that portions of the Plains will have received local snow amounts of up to 18 inches with thundersnow, temperatures after the storm will rise above freezing, our official snow so far this winter is only 10.9 inches, and the bulk of the snow will fall overnight, not a big deal in my opinion. We certainly have experienced a lot worse. At the south end of the storm there will be severe storms with possible tornadoes.
Weather for the weekend will not be bad, highs will be in the low to mid 30s. Our normal high is now up to 37, so we will be "normal." Another weaker system will move through the Midwest and Chicago area early next week. This will provide much lighter rain and snow.
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