BNSF 5756 (ES44AC) muscles a freight through a frosty east Rollinsville, Colorado on the Moffat Tunnel Sub. Heavy fog and snow has covered the valley and nearby mountains.

Heavy snow is falling at Tolland, Colorado, obscuring the east portal of the Moffat Tunnel from which UP 6864 (ES44AC) has just emerged.

A large herd of elk greets BNSF 6295 (ES44AC) as it runs a freight through a foggy and snowy Rollinsville, Colorado on the Moffat Tunnel Sub.

BNSF 6295 (ES44AC) leads the Provo to Denver train out of the east portal of the Moffat Tunnel and into light snow falling over Tolland, Colorado.

Snow and flocked the trees and fog shrouds Coal Creek Canyon as the California Zephyr runs through the cut leading to the climb towards Tunnel #1.

AMTK 198 (P42DC) skirts the base of Blue Mountain as it heads into Coal Creek Canyon on the Moffat Tunnel Sub.

UP 7801 (ES44AC) leads a train through Little Ten Curve at Rocky, Colorado.

UP 1507 (GP40M) passes the Union Pacific's operations building at the North Yard in Denver, Colorado.

UP 9581 runs into light snow showers as it exits the east portal of the Moffat Tunnel with an oil can train.

As a passenger watches out the rear window, the California Zephyr 5 train gets ready to enter the east portal of the Moffat Tunnel.

As light snow falls over Denver, Colorado, the California Zephyr 5 train gets ready to back into Union Station, which sits amongst the high-rise buildings.

It seems the California Zephyr is destined to be led by a pair of Phase VII P42's. This colorful consist is a welcomed addition for photographs along the Moffat Route.

The California Zephyr 5 train has left Denver and is running towards Rocky, Colorado on the Moffat Tunnel Sub.

Long live the Warbonnet! BNSF 704 (Dash9) pulls up for service at the engine facility in Denver, Colorado.

UP 8714 (SD70ACe) exits the Hermosa Tunnels hauling a heavy transformer towards Laramie, Wyoming.