(NBC) - It's May and in Colorado they are still shoveling snow.

By the time the weather system moves through later tonight there could be up to 18 inches of snow in some areas.

The heaviest snow is in southern Wyoming and northern Colorado.

In Denver the accumulation could be between five and eight inches.

When you combine the falling snow with wind gusts of 10 to 20 miles an hour, it causes some visibility problems along the highways.

Power outages have also been reported.