Is It Time To Redefine Winter Weather?

We expect winter to bring about blizzards, heavy snow, ice storms and bitter cold. But this winter is a reminder that climate change is forcing us to rethink traditional definitions of seasonal weather events and the related public safety and economic impacts. While the typical cold and snow are happening this winter, climate change is fueling tornado outbreaks, derechos, and wildfires. The increasing frequency of these traditionally spring or summer weather events are driving the need to rethink our winter weather preparations. 

Meteorological winter began as one of the most unusual winters ever on record. It started with a deadly tornado outbreak across the central U.S. in mid-December, with more than 60 tornadoes reported across Kentucky, Arkansas, Tennessee, Missouri, Illinois, Georgia, Ohio, and Indiana. Most of these storms happened at night, leaving more than 80 people deadand causing devastating damage to communities. Tornado outbreaks of this magnitude are most common during the spring and summer, not December. The National Oceanic and Atmospheric Administration estimates the likelihood of a tornado occurring on a typical December day is just 12-15 percent, as compared to a 90 percent chance of a tornado happening in early June.

That tornado outbreak wasn’t the only extreme weather event in December. Many cities across the Midwest had record-high  temperatures, and that energy helped fuel one of the most unusual storms to ever occur in the Midwest.  A major windstorm, spanning 650 miles from Kansas to Wisconsin produced at least 61 tornadoes and more than 560 reports of damaging wind. In many states, it was the first time in history that tornado warnings were issued in December, and a record-setting number of those damaging wind reports involved wind gusts of more than 75 mph.  This storm was ultimately found to be a derecho, which is a widespread damaging windstorm produced from thunderstorms. In this case, the serial derecho was driven by an intense cold front colliding with the above-mentioned warm air. A rare occurrence any time of the year, this was the first derecho on record anywhere in the United States.   

December’s extreme weather events didn’t end there. The month ended with the most destructive wildfire in Colorado history, the Marshall fire, just outside of Boulder. The fire started on Dec. 30 and burned more than 6,000 acres in less than 24 hours, destroying almost 1,000 homes and buildings. The fire was fueled by hurricane-force winds gusting up to 105 mph and dry vegetation. Researchers at the University of Colorado, Boulder say that climate change is lengthening the state’s fire season, and that last year was an unusually dry year.

These out-of-season weather events have proved to be quite costly, both to human lives, and economically as well. Early reports show the December tornado outbreak resulting in insured losses of up to more than $5 billion. Although the Marshall fire in Colorado wasn’t the biggest fire in the state’s history, it is the most destructive because of the urban landscape it destroyed. Early estimates on the total insured losses of residential properties impacted are around $1 billion.

While this traditionally summer weather events happening in winter makes for interesting conversation and news coverage, the consequences are serious and real. There are both significant public safety and economic losses from events like these, creating both the need for building awareness and preparation plans for these types of events in the future.