For parts of the Front Range on Sunday night, it looked like the ocean had magically turned into the sky.
Waves — literal cloud waves — could be seen across much of the southern part of the Denver metro area on Sunday night, illuminated by a stunning orange glow over the evening sky. Those created a type of cloud rarely seen over the Colorado skies — or anywhere for that matter. Kelvin-Helmholtz clouds made a rare appearance over parts of south Denver, Aurora, Centennial, Lone Tree and Englewood at sunset on Sunday.
Beautiful Kelvin-Helmholtz clouds over #denver tonight! #9wx #Colorado pic.twitter.com/h15aLpKwDG
— Rob Fields (@NORMALKIDROB) November 18, 2019
More waves from SE Aurora 📷: Katie Nellis pic.twitter.com/lb0y9bDWK5
— Cory Reppenhagen (@CReppWx) November 18, 2019
A relatively rare and localized set of meteorological circumstances created ideal conditions for Kelvin-Helmholtz clouds. At the surface, winds were calm along the Front Range on Sunday. Denver International Airport reported a “calm” wind speed for four straight hours on Sunday afternoon.
But above the surface, strong winds were noted just above the cloud deck, creating wind shear — the change in wind speed (and/or direction) with a change in altitude. That sudden and rapid change in wind is important: it creates a much faster wind over a much slower — or nearly stationary — layer of air.
KH clouds helped by weak/no winds at the surface, rapid increase just above the LCL. NAM sounding over Denver tonight:#COwx pic.twitter.com/O3TY6lL8LZ
— Chris Bianchi (@BianchiWeather) November 18, 2019
With much faster winds moving right over a slower cloud layer, the stronger winds essentially helped scoop up the clouds below, creating the clouds’ wave-like appearance.
Think of it like a strong wind over the surface of the ocean: the force and pull of the wind creates the waves. The same thing happened over the skies of parts of the Denver metro area on Sunday night, creating a spectacular sunset display, even by Colorado’s lofty standards.
