This week's historic winter storm could rival the infamous Halloween blizzard of 1991

[THEME MUSIC] CATHY WURZER: But of course, the story we're talking about-- and you will, too, especially by Thursday-- will be the potentially historic winter storm that's incoming. 20-plus inches of snow and 45- to 50-mile-an-hour winds should get your attention. Joining us-- fresh from a lovely vacation and just in time for the storm-- is our meteorologist Sven Sundgaard. Hey, welcome back.

SVEN SUNDGAARD: Hey, thanks for having me. I can't complain, I guess. I got recharged a bit.

CATHY WURZER: Good, I'm glad. And then, right in time-- your timing is excellent. So I mentioned about 20 inches in our lead to the conversation here. Who is likely to see 20 inches?

SVEN SUNDGAARD: The Twin Cities is in the thick of that. It could be us, anywhere from Marshall to Glencoe. You know, Mankato, Rochester, and the Twin Cities-- really, we are in the bull's eye of this system.

And it's going to be a range of-- on the low end in that heavy swath-- maybe 14 inches. That's still very significant. But there could be some isolated spots that get up to 2 feet, so that's kind of the range we're dealing with here.

And it's going to depend specifically on the ratio of snow to water. This is not going to be a 10-to-1 event. It's probably going to average out to be about 16 to 1.

So you take what is already an impressive storm with lots of moisture, over an inch of water. You multiply that by 16. You get how we get to these pretty incredible numbers here by the time it wraps up midday Thursday.

CATHY WURZER: Wow. OK. So I just was looking at some traffic management cameras out west. Looks like Hendricks, Minnesota, yeah, Sioux Falls, where they tend-- they're getting the snow right now. What might it be in the Twin Cities metro area?

SVEN SUNDGAARD: Yeah, so as you mentioned, it's mostly the southwestern counties right now. Windom, Jackson, towards Marshall-- mostly west of the Minnesota River. We can expect it to slowly crawl east this afternoon, probably making its way into the Twin Cities by between 2:00, maybe as late as 3:00, 3:30 PM this afternoon.

But it does look as though for that evening commute, it will be snowing. And some of the heavier snowfall with this first round-- it is coming in two rounds, this storm. But this first round will probably be in that 4 to 7 PM timeframe.

So we won't have a lot of snow on the ground or the roads yet for the evening commute, but it will be snowing. So anticipate it being pretty slow then. And with this first round, we're looking at, probably, a good 4 to 7 inches for most of-- from Redwood Falls through the Twin Cities, maybe slightly less around St. Cloud, just north of it, 4 to 6.

You get further north-- quite a bit less 2% to 3% around Brainerd. And then, south-- also a little bit less. Rochester-- may be 3 to 4 inches and only about an inch in Albert Lea. So again, with this first round, too, it's going to be that swath of Marshall, Redwood Falls, through Glencoe and the Twin Cities that we get the heaviest.

CATHY WURZER: And don't be fooled, because the second round is coming.

SVEN SUNDGAARD: Yeah, it's important that people pay attention to the specific information with this storm, because you might see tomorrow morning, mid-morning, the snow lightens up or maybe even briefly stops, and say, well, we only got 6 inches of snow. Well, that's just the first round.

We'll get a bit of a mid-day lull, not a complete break. But then, as we head into the late afternoon, yeah, the snowfall rates really pick up, and it's this second round that's going to be the real doozy here. That's where we will see the heaviest snowfall, up to 1, to even 3-inch-per-hour snowfall rates are going to be possible in some of the heavier bursts.

And where that heaviest band sets up is still a little bit of a question. So that's why we're going to see that range of 14 to as much as 24 inches of snow. By tomorrow afternoon, we'll really know where that very narrow area of heavy snow sets up, but that second round is going to dump a foot to a foot and a half of snow from similar areas-- Redwood Falls through the Twin Cities into Western Wisconsin.

And this is when we'll see places like Duluth get in on a little bit more of the snow-- 2 to 4 inches of snow there. And they're looking at a potential total when you add up the two rounds for places like Duluth-- probably, 8 to 10 inches-- still a significant storm by any measure, but significantly less than what we're going to see here in the southern half of the state.

CATHY WURZER: Saw that guidance from NOAA earlier this morning, about how they have storm impacts and their categories. There's, like, from 0 to 5. And the Twin Cities is in, what, the extreme impact category? Actually, a swath from western through central Minnesota into the Twin Cities. Have you ever seen that before?

SVEN SUNDGAARD: No, and this is something new that they've been trying for the last several years, and this is the first time that they've ever had the Twin Cities in that extreme impact-- their highest level. That means travel will be next to impossible tomorrow night into early Thursday. So we really want to stress to folks, whether this is the second-biggest snowstorm or the fourth-biggest snowstorm in Twin Cities history, this is something that most of us haven't dealt with in over three decades.

If you were under the age of 32, you've never seen a storm like this. And this is probably going to beat the 2010 storm that took down the Metrodome roof, so this is something to really take seriously. Flights are going to be canceled. There's going to be, probably, a backlog of that.

And roads are going to be just nearly impossible across southern Minnesota. And even though the snow will stop around lunchtime on Thursday, it's going to take some time to really clear up those roads, especially since it's going to get pretty cold here Thursday night into early Friday.

CATHY WURZER: The dome buster-- wasn't that 17 inches?

SVEN SUNDGAARD: 17.1. And it does look as though we're likely to beat that.

CATHY WURZER: All right. Well, we will keep track of it. I know you will, and the other meteorologists. Thank you so much for this early update.

SVEN SUNDGAARD: You're very welcome, Cathy.

CATHY WURZER: We've been talking to meteorologist Sven Sundgaard.