The California Zephyr runs through the aspen trees in Tolland, Colorado as it heads west on the Moffat Tunnel Sub.

Amtrak engine #76 leads the California Zephyr west towards Tolland, Colorado on the Moffat Tunnel Sub.

Snow falls in the Colorado Rocky Mountains as UP 9088 (SD70ACe) leads a freight through Tolland, Colorado on the Moffat Tunnel Sub.

Heavy snow falls in the Colorado High Country as UP 5306 (ES44AC) leads a freight through Tolland, Colorado on the Moffat Tunnel Sub.

Snow flurries fall over the Tolland Valley as BNSF 5146 (Dash9) leads a freight east on the Moffat Tunnel Sub towards Rollinsville, Colorado.

Light snow greets BNSF 8419 (SD70ACe) as it runs past the signals in Tolland, Colorado on the Moffat Tunnel Sub.

Light snow has iced the rocks in Tolland, Colorado as BNSF 5919 (ES44AC) shoves a freight east on the Moffat Tunnel Sub.

BNSF 5919 (ES44AC) muscles a freight past a snowy, fast-flowing Boulder Creek at Tolland, Colorado.

Snow is falling on the valley at Tolland, Colorado as BNSF 8419 (SD70ACe) leads an eastbound freight on the Moffat Tunnel Sub.

BNSF 6086 (ES44C4) swaps lead engines after a problem with the train in Tolland, Colorado.

BNSF 5146 (Dash9) emerges from the east portal of the Moffat Tunnel and into snow as it heads through Tolland, Colorado.

Heavy snow falls on UP 7789 (C45ACCTE) as it leads a freight west on the Moffat Tunnel Sub through Tolland, Colorado.

A spring snowstorm in the Colorado High Country drop snow on UP 5306 (ES44AC) as it runs through Tolland on the Moffat Tunnel Sub.

Light snow falls in Tolland, Colorado as BNSF 7073 (ES44AC) shoves the Provo-to-Denver train into the Winter Wonderland of flocked pine trees on the Moffat Tunnel Sub.

Snow is falling in Tolland, Colorado as UP 7789 (C45ACCTE) leads a freight west on the Moffat Tunnel Sub.