A storm system over northern Colorado will intensify later today and push into the southeast corner of the Cowboy state tonight.   Mountain snow and wind are likely over the southern Snowy and Sierra Madre Ranges.   Thickening clouds and snow showers will push into the southeast tonight, extending north to the Casper area overnight.   Snowfall will accumulate enough (2 to 5 inches) to create slick and icy road conditions tonight into Wednesday.   Travelers will need to use extra caution while driving through mid-week.  Temperatures will become colder, with highs tomorrow only rising into the 20's.  Snow showers will linger across the far southeast corner through Wednesday afternoon.