Almost two years to the day after the devastating central U.S. bomb cyclone of March 13, 2019, a powerful storm system formed in the high plains of eastern Colorado, bringing heavy snow and blizzard conditions to the high country and heavy rain to lower elevations. The occasion and the atmospheric elements were striking.
The storm system's production was also similar to the March 2019 event. Heavy snow blanketed the Rockies in Colorado and Wyoming, and fanned out across western and northern Nebraska, South Dakota, Minnesota and northern Iowa. Heavy rain drenched the plains of Colorado, Kansas and Nebraska. Winds howled at up to 50 miles per hour.
But, while weather bulletins featured winter advisories and winter storm warnings, a feature from the 2019 storm impact array was noticeably lacking. That feature was flooding. Nebraska state climatologist Martha Shulski's tweet on March 14 encapsuled the difference:
"Several inches of rain in eastern #Nebraska, blizzard in the west, strong winds gusting above 40 mph," Shulski tweeted. "Storm is quite similar to 2019 cyclone. The big difference is setup -- no snow, river ice, warm soils, dry conditions at the start prevent a repeat #flood of 2 years ago."
When the bomb cyclone formed in 2019, the north-central U.S. soil moisture profile was brim-full after a record year of precipitation in 2018. Any subsequent precipitation had nowhere to go. In addition, prevailing cold during the first half of March further hardened the ground and froze the filled-up rivers with thick ice. When the 2019 cyclone formed, its combination of striking air mass contrast and resulting heavy rain and snow not only brought new moisture to the central U.S., but forced a rapid melting of the river ice to create gigantic ice jam flooding. The storm flooded an estimated 1 million acres of U.S. farmland.
The central U.S. has already had a record storm system in the first quarter of 2021, when the powerful Arctic cold wave and blizzard system of mid-February occurred. The mid-March storm indeed brought the heavy precipitation, but pre-event conditions appear to have kept the March storm from joining 2019 in a massive rewrite of March storm descriptions.
Bryce Anderson can be reached at email@example.com
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