Mon-Wed, Jan. 14-16th Mixed Precip Event

​(6:00PM - 1/14/19) A period of light mixed precipitation is likely from later this evening on into Wednesday, across portions of Northern and Central Illinois.

Sounding from Chicago/O'Hare for Tuesday morning, showing the shallow moist layer and surface temps below freezing.

A complex scenario is setting up for this period, which will likely result in multiple precip types and fog being likely across Northern and Central Illinois. The environment will feature a shallow moist layer from the surface up to around 3KFT. This will allow the collection of moisture above to eventually fall to the surface as light precip. Deeper moisture content throughout the atmosphere will prevent anything more than periods of very light and scattered precip, along with some fog. The shallow nature of the deeper moisture and warmer temps aloft at times will also lead to precip type issues, as there will be a lack of ice crystal formation within the clouds. This is often seen within environments with shallow moisture depth, which usually leads to drizzle and/or freezing drizzle being the main precip types. In this case, surface temperatures likely for remain at or below freezing for most areas during the period, thus freezing rain will be the likely precip type. This will lead to icing concerns for many areas, with a  glaze of ice possible. It is possible for temps to reach at or slightly above freezing for some areas of Central Illinois and the Chicago metro on Wednesday, which may turn precip to drizzle for a time. A few areas may also turn to snow grains at times, where moisture depth gets deep enough and coincides with cloud ice crystal formation. 

Total ice accumulations of a glaze is likely for many areas, with any snow grain accumulation of a dusting expected for Northern and Central Illinois.

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JP