Why this weekend's US winter storm is expected to be so widespread

By Brian Kahn

 

The eastern two-thirds of the US is gearing up for a major winter storm. Ice, sleet and snow will spread across an area spanning thousands of miles. 

While parts of the US have dealt with major winter storms in recent years, from California being pummeled by atmospheric rivers last year to Texas’ 2021 deep freeze, the country hasn’t seen any with this geographic scope. But two factors are lining up to create a weather system that’s forecast to grip dozens of states from New Mexico to Maine. 

 

The first is cold air. After all, snow and ice can’t happen without temperatures below freezing. The big chill comes courtesy of a huge dip in the jet stream, a band of air that moves from west to east. But it’s occasionally prone to wild swings, like the one currently over North America that has cold air riding it out of Alaska and swooping across the southern US. That dip — also known as a trough — will cause temperatures to drop well below seasonal averages.

 

“The large-scale nature of the pattern also means that we’re getting a widespread region of cold and not just getting clipped by a short cold spell,” said Andrea Lopez Lang, an atmospheric scientist at the University of Wisconsin-Madison. 

 

With that cold in place, the other key ingredient is moisture. That’s coming courtesy of a weather system that will blow in from around Baja California. While relatively smaller scale, it will act like a pulse of energy in the atmosphere. 

 

If these two atmospheric pieces “come together perfectly, that then is the recipe and ingredients for a really big storm,” said Curtis Walker, a scientist at the US National Science Foundation National Center for Atmospheric Research. 

 

With Texas in particular gearing up for hazards and potential power outages, it’s tempting to compare this to the 2021 freeze that killed dozens and left millions in the dark for days on end. But while there are similarities, this storm is forecast to be bigger and shorter.

 

During the 2021 event, cold weather caused gas power plants to fail. But this time, significant icing will extend beyond Texas, expanding the risk of outages caused by broken or downed power lines. Lopez Lang pointed to a widespread ice storm that struck Canada and the US Northeast in 1998 as a point of comparison. That event caused inflation-adjusted damage of $2.7 billion in the US alone, including widespread damage to the grid and forests.

 

The ice from this storm will likely threaten areas less acclimated to winter weather and also impact major airport hubs, including Dallas-Fort Worth, Atlanta and Charlotte. More than a foot of snow is likely to fall across a large part of the Northeast, including New York, further snarling travel. If the forecast bears out, it would be one of the most significant snowstorms since a 1993 storm, said Rob Carolan, chief executive officer of Hometown Forecast Services.

 

Thousands of miles of interstate highways are also expected to be hit by snow and ice, creating a “unique set of impacts” for repair crews to respond to, Walker said.

 

While the worst of the snow and ice will likely clear out of the US by Monday, freezing temperatures will linger in the days after. That’s due to the large nature of the trough, Lopez Lang said, and because the source of the cold air from the north “is open and is fairly persistent.”