At an altitude nearly two miles high, one would not expect a funnel cloud to appear in the sky over a town like Leadville, Colorado. On Sunday however, Mother Nature treated visitors and residents to a rare ‘cold air funnel’ over the town high in Colorado’s Rocky Mountains.
At approximately 10:30 a.m. on Sunday, the funnel was spotted over Leadville where it continued to rotate for nearly 20 minutes, according to observers. The funnel never touched down, thus never becoming a tornado, but it serves as a reminder that twisters can occur just about anywhere on earth.
Funnel clouds and tornadoes typically need four conditions to form – Shear, Lift, Instability and Moisture (SLIM as famed storm chaser Roger Hill calls it). With a cold air funnel, those conditions also exist, although they aren’t associated with a supercell thunderstorm like is seen on the plains.
According to the National Weather Service’s Pueblo office, a cold low pressure system over northwestern Colorado provided the instability part of the equation. Strong upper level winds over the southwestern part of the state and slower winds over the northwest provided shear. The difference in lower and upper level temperatures and a passing thunderstorm provided the lift and moisture for the funnel.
One Denver-area television station is incorrectly reporting on its website that “Leadville was never in any danger because he says cold-air funnels do not turn into tornadoes.”
This is wholly inaccurate. While cold air funnels do not typically touch down, they can reach the ground and as the National Weather Service states, they “can bring damage in a small area.”