A storm moistening as it crosses the central Rockies will tap enough cold airto drop heavy snow over a part of Colorado and Wyoming beginning lateTuesday.As the instigating storm tracks eastward over the Intermountain West, rain willbreak out in earnest over Wyoming Tuesday. At first, snow will keep to themountains, but the snow level will lower to the open plains and valley floorsTuesday night.

Rain and snow will also crank up southward over the northern half of Colorado.

The threat of heavy snow will last well into Wednesday between east-centralWyoming and the eastern slopes of northern and central Colorado.

Higher-end snowfall above 7,000 feet will reach 1 to 2 feet in areas crossed byhighways I-70 over the Colorado Divide, and I-80 through central and easternWyoming. Substantial snow will also cover stretches of I-25 from Cheyenne toCasper.

Needless to say, this storm will bring full-on winter driving conditions toparts of both states.

The weather will improve markedly on Thursday.

Story by AccuWeather.com Senior Meteorologist Jim Andrews.