Cold front slows, gives a better chance of snow

Mild moist southerly flow will strengthen early this week, with cloudy skies and a slowly increasing chance of significant rain. If forecasts are accurate, highs the first four days of the week will average nearly 20 degrees above normal. Precipitation is in the forecast every day of the work week, probably peaking just in advance of and in the wake of a cold front Wednesday and Thursday. Latest atmospheric models indicate a cold frontal passage in the Chicago area sometime Wednesday night and a subsequent slow movement east, allowing time for a dynamic low pressure development in Ohio Thursday. The progress of colder temperatures into northern Illinois could slow, extending the period of post-frontal rains through a good portion of Thursday. If the low forms in Ohio by Thursday evening, cold northwest winds will strengthen, and rain will change over to wet snow in Chicago. Some snow accumulation could then occur in Chicago on Friday morning.
--By Paul Dailey, WGN Weather Center Meteorologist