What to expect as a massive, powerful winter storm wallops the U.S.

William Brangham:

Good evening. I'm William Brangham. John Yang is away. A fierce winter storm is barreling across the country with more than 70 million Americans under winter weather alerts tonight and 4 million of those facing blizzard conditions. At least six governors have declared states of emergencies.

Today, bitter cold winds whipped through the Great Plains and heavy snow blanketed parts of the Northeast. The massive weather system will reach the Mid-Atlantic area later tonight. In the coming days, it's expected to bring frigid temperatures as far south as Florida.

Matthew Cappucci is a senior meteorologist at the MyRadar app. Matthew, thank you so much for being here. When you look at what is coming down now and what is forecast to come, what is it that most concerning to you?

Matthew Cappucci, Senior Meteorologist, MyRadar:

I think for me, it's the fact that we're not seeing just snow. It's the mix, the icy, wintry mix, the freezing rain and the sleet that's really complicating things. You know, when we have freezing rain, it's difficult because that liquid initially washes all the pretreatment off the roadways. And so crews can't really get ahead of the game with situations like this.

The other thing, too, is that behind this system, bitter cold arctic air is infiltrating the planes spreading east across the Ohio Valley. And so it's not just the fact that we're seeing power outages now down the road. If more people lose power, they'll be without any warmth for days on end.

William Brangham:

Why is that we're seeing if it's this cold and this much snow coming down, why are we also seeing rain in the midst of that?

Matthew Cappucci:

Great question. You might think it's 30 degrees at the surface, why is it not snowing? One of the issues with this system is twofold. It's bringing something north called a warm nose. Basically this river nose —

William Brangham:

Warm nose.

Matthew Cappucci:

Warm nose, this river of warmth and moisture at the middle levels. It's swirling at north in the Gulf of Mexico. So all that moisture is why this is a water loaded system. We're seeing so much snow, so much sleet, so much freezing rain.

But those warm temperatures aloft allow any precipitation to fall as liquid because temperatures are above freezing. And then there's that shallow layer of cold at the surface. So in many cases, especially in the Ozarks of southeast Missouri near the Ohio River, we're seeing precipitation fall as liquid and then freeze right on the ground, causing an ice skating rink.

Up to about a half inch of ice accretion is likely in some areas, meaning that's enough to pull down power lines, knock over tree branches, and that's in addition to heavy snow farther north.

William Brangham:

Help us put this into context. I mean, it is January. People expect snow, they expect cold. This does seem to be a little bit out of the ordinary, though.

Matthew Cappucci:

I think what strikes me the most is how widespread it is. We have winter storm warnings, blizzard warnings and alerts for about 1500 miles from Kansas to the Delmarva Peninsula. So this could be DC's biggest snowfall since 2022, but it's setting records really across the entire country.

One other thing, the system's backlash on the backside with the cold air kind of wrap around in Kansas right now is actually set to produce a blizzard conditions later on tonight with winds gusting to 40 miles per hour. So really, every type of hazard is on the table with this system. I think a lot of folks will be seeing pretty significant disruptions for quite some time.

William Brangham:

And I imagine travel is going to be near impossible in a lot of these.

Matthew Cappucci:

Yeah, it goes back to what we're saying earlier on with the pre-treatment just not being able to be put down due to the mixing issues with the freezing rain. So that's been a big headache. The reduced visibility is with the strong winds. Lofting freshly fallen snow has been a headache too. I know aviation is a big problem right now. Hundreds of flights have been canceled across the country.

And part of the problem too, even if you can get the planes in, you can't get them back out. So, really it's sort of cascading flight delays right now. Interstates will be very rough, if not impassable. It's one of those situations where we hope folks can just stay home for 24 or 36 hours, wait for things to get better and eventually by Tuesday into Wednesday, most folks should be in a much better state.

William Brangham:

What else on that front that people can do to stay safe and to be smart in the midst of all this?

Matthew Cappucci:

I think realistically it's about not going out on the roads and really just sort of waiting this one out. I think so often we're tempted to go out to see to sort of, you know, get a firsthand perspective and in this situation shouldn't be doing that.

One really interesting element with this too, and it will sound so bizarre for the folks at home, but it's a lightning loaded system too. We've seen thundersnow across Kansas.

William Brangham:

Thundersnow.

Matthew Cappucci:

Thundersnow. There's so much. Remember that warm nose, the warm air at the middle levels is allowing some upward motion in the clouds enough to get sparks of lightning. And so people might be trying to shovel and flash of lightning comes down. Same thing with the freezing rain, the ice, the sleet. So if you can hear thunder, you shouldn't be outside shoveling.

And that's something people always forget this time of year. But realistically, the lightning can be danger too. Time to just kind of wait this one out.

William Brangham:

And what like — how many days should people expect this? And then do things clear up? Do people look like there's some relief in sight?

Matthew Cappucci:

Yeah. So things will wind down west to east beginning overnight tonight for the Plains. But that's just when it's really getting going for the east coast in D.C. For example, we'll see things wind down likely by say Tuesday morning. And you might think great, is the active weather over? Not really so fast. There are signs we could see a new system begin to form near Texas sometime Friday into the weekend. With some cold air in place, wintry mix could be an issue once again. And there's a chance that system could track up the eastern seaboard.

William Brangham:

Well, Matthew Cappucci of the MyRadar app, thank you so much.

Matthew Cappucci:

What to expect as a massive, powerful winter storm wallops the U.S. Thank you.