If a state trooper had been clocking Saturday’s storms in western Colorado, they might’ve had to pull them over for speeding.
Severe thunderstorms in western Colorado and eastern Utah were moving as fast as an estimated 120 mph late on Saturday morning, according to the National Weather Service office in Grand Junction, among the highest speeds ever seen in association with a severe thunderstorm warning.
There are no official records for the estimated speed of a storm, but a forward speed above 100 mph is considered to be meteorologically off-the-charts. A one-hour radar loop showed the storms likely moving near 100 mph for the duration of an hour as they moved from west-central into northwestern Colorado.
— Chris Bianchi (@BianchiWeather) June 6, 2020
The storm speeds drew attention from meteorologists across the country on Saturday, with several commenting on the unusually fast forward motion of the storms.
A sharp upper level area of low pressure spinning through the western U.S. was responsible for the highly unusually fast-moving storms on Saturday, which also led to notable wind-producing storms across Colorado and much of the inner-mountain West.
While winds at the upper levels of the atmosphere are typically confined to air well above the surface, the strong upward motion of Saturday’s storms allowed them to mix down to the surface. That led to wind speeds that topped 50 and even 60 mph across much of the Front Range on Saturday afternoon, before the storms even arrived.
A sharp contrast between cool, dry air behind the system and warmer and more humid air ahead of it allowed for fast forward speeds of the storms as well. Cooler and drier air is denser than warmer and more humid air.
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