WFO Pueblo received reports of a funnel cloud observed near Leadville, Colorado (elevation around 10,000 feet), Sunday morning at around 10:30 am MDT. This photo was sent to us courtesy of Channel 9, KUSA, Denver.
National Weather Service Doppler radar at the time showed what appeared to be an innocuous line of showers associated with cumulonimbus clouds.
This appears to have been an impressive case of a cold air funnel. A cold air funnel cloud, which can rarely develop into a small, relatively weak tornado, can develop from a shower or weak thunderstorm when the air aloft is unusually cold (hence the name). In this case, a cold upper-level low pressure system was located over northwest Colorado, resulting in increasing atmospheric instability. The upper level winds over southwest Colorado were quite strong, while they were much weaker over northwest Colorado. This resulted in a great deal of wind shear and vorticity (the tendency for the atmosphere to spin). The resulting combination of atmospheric conditions was a good recipe for cold air funnel cloud development. The atmosphere never ceases to amaze!