Most of Wyoming is under a winter storm warning, advisory or watch from the National Weather Service as snow and frigid temperatures begin to descend upon the Cowboy State.

Casper will see about seven inches of snow, with a foot expected in the Jackson area and three inches or so for Laramie and Cheyenne from Wednesday through 5 p.m. Friday.

Casper's low temperature will be around 15 F Wednesday night, but it's expected to fall to -15 F on Saturday -- and that's without wind chill.

Conditions on Interstates 25, 80 and 90 are expected to be extremely poor, and travel will likely be hazardous.

The storm will first hit western Wyoming around noon Wednesday with heavy and wet snow  from mid-mountain areas to valley floors, according to the National Weather Service's storm impact index.

Areas east of the Continental Divide could see light snowfall for 3-6 hours Wednesday night into early Thursday morning.

Lower elevations, especially across southwest Wyoming, may see snow mix with or change to rain as warm air moves into the area Thursday.

The western part of the state could see a Pacific Storm moving east and combining with a system coming out of Canada to produce another round of heavy snow Thursday night through Friday night.

Significant snow will likely develop east of the Divide late Thursday night into Friday.

Conditions are expected to improve from northwest to southeast Friday night into Saturday morning -- but bitterly cold temperatures are expected early next week as an Arctic cold front pushes into the state.

Temperatures across Wyoming may not rise above zero in some places Saturday and Sunday.

The National Weather Service advises that people stay indoors if possible, and be sure to dress appropriately if they must go outside.

Travel will be difficult with the weather. But if you must drive, be sure to have a winter safety kit in your car.