Dense Fog in San Juan River Basin, Colorado

Patches of dense fog developed over portions of the San Juan River Basin following a round of snow showers in the early morning hours on November 21. The KPSO AWOS at the Stevens-Pagosa Springs Airfield reported two brief periods of 1/4-mile visibility from freezing fog before sunset. No reports of injuries, damages, or fatalities were received.

A zone of deformation set up over the region ahead of a closed low, but a deep moist layer remained across the west slope of the Rockies. Overcast skies during the afternoon of November 20 kept the cool temperatures and near-saturated environment in place. This supported another round of snow showers early in the night of the 20th and the subsequent development of widespread dense fog.