Spring and fall in Colorado are known for rapid weather changes, snow one day and sunshine the next. But there’s another atmospheric oddity that occasionally spins through our skies — the cold air funnel cloud.
What Are Cold Air Funnels?
Cold air funnels are slender, rope-like funnel clouds that form beneath showers or weak thunderstorms when the air high above us is especially cold — typically between 15,000 and 20,000 feet up. These funnels usually don’t touch down, and they’re far weaker than the tornadoes we associate with severe thunderstorms. Sometimes (rare), they can reach the ground and cause EF-0 level damage (winds up to 85 mph).
Why Do They Happen in Colorado?
Colorado’s mix of elevation, mountain-enhanced weather, and seasonal cold air aloft makes it a prime location for cold air funnels — especially in the spring and fall. During these seasons, the sun can heat the ground enough to create rising air pockets (called convection), even as very chilly air lingers above. This contrast creates the perfect environment for cold air funnels to form, especially behind passing low-pressure systems or weak surface troughs.
Are Cold Air Funnels Dangerous?
Most of the time, cold air funnels are harmless — more of a curiosity than a threat. They rarely touch down and usually don’t last long. In fact, the National Weather Service (NWS) often won’t issue a tornado warning unless a funnel is confirmed to be reaching the ground. Instead, they might release a Special Weather Statement to let the public know what’s going on.
Still, if you see a funnel cloud, treat it seriously. If you’re unsure whether it’s a cold air funnel or something more intense, it’s always best to take shelter and report what you saw to the NWS. These types of funnels are difficult to detect on radar because they’re so weak — that’s where your observations become essential.
What to Look For
- Thin, rope-like funnels descending from high-based clouds
- Calm or lightly rainy weather nearby — not a severe thunderstorm
- No strong rotation signature on radar
- Often seen on clear, breezy days following a cold front
Colorado’s Reminder: Stay Weather-Aware
Cold air funnels are just one of many unique weather phenomena Coloradans get to experience. While they don’t pose the same threat as typical tornadoes, they’re a great reminder of how dynamic and fascinating our atmosphere can be — especially in a state where the weather can change in minutes.
So next time you’re out hiking or enjoying a sunny fall afternoon and spot a skinny spiral descending from a puffy cloud — don’t panic. Snap a photo (safely), report it, and know that you’ve witnessed something rare and very Colorado.