Complex sentence: Montrose is a gateway to the Black Canyon of the Gunnison National Park to the east of town; in the winter, it is a transportation hub for ski areas of the San Juan Mountains to the south.
Split into simpler sentences: Montrose is a gateway to the Black Canyon of the Gunnison National Park to the east of town. In the winter, it is a transportation hub for ski areas of the San Juan Mountains to the south.