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TOM CRANN: Our chief meteorologist, Paul Huttner, joins me now here on Minnesota Public Radio News. And, Paul, I want to talk about what built up to this. We have seen pretty extraordinary rain totals in the last 24 hours or so. But did this event just happen out of nowhere, or was there a buildup leading up to it?

PAUL HUTTNER: Yeah, there really was. I mean, we're going to look back and call this the Great Duluth Flood of 2012, no doubt. But it really had its roots a few days ago. It didn't just start today in terms of the weather pattern that's set up to cause this flood.

Here's the deal, Tom. Let's go back to the weekend, Sunday night, Sunday afternoon, when the warm front pushed in through the Twin Cities. The metro had severe storms roll through with a quick inch of rain on Sunday night. Then that warm front slid north. The metro made it to 90 degrees Monday.

It hung around and spawned another batch of severe storms Monday night that started out in West Central Minnesota. It was one of those bow echoes, these mesoscale convective complexes, that slid east. And that one tore up the south metro with hundreds of trees down. We had gusts to 83 miles an hour in Belle Plaine. That complex blew through.

Then Tuesday, we were on the warm side of the front. Hot and windy yesterday in Southern Minnesota, 93 in the metro. And the front late last night was draped from about around Saint Cloud to south of the Hinckley area. So that's south of Duluth. And that's a classic setup. We had an east wind off of the lake about 15 miles an hour, blowing into the Duluth area and up the hill.

Well, why is that important? Because that provided just a little more what we call orographic lift to the situation last night. And with that warm front sitting there and all that hot air from Southern Minnesota just piping north into the frontal zone, that's what we call a classic overrunning situation.

These warm fronts are notorious for getting going at night. And the thunderstorms developed and began just moving over the same ground or training, as we call it. We had that upslope wind off of Lake Superior, little topographic enhancement there, maybe a little lake enhancement from additional moisture. You put all that together, Tom, it was really the perfect storm for the Duluth area and much of Northeastern Minnesota last night and early this morning.

TOM CRANN: This situation, the orographic lift, we were talking about that. Can you liken that with rain to the way lake effect snow happens?

PAUL HUTTNER: Exactly. Right. Now, there's about 1,000 foot rise from the surface of Lake Superior up to the top of the hill on the North Shore in places and near Duluth. And that actually helps sustain some of those updrafts when you get a wind coming off the lake and going up the hill like that. So that's one of those mesoscale features, as we call it, a localized feature that may have helped to boost those rainfall totals right in the Duluth area.

TOM CRANN: And those rainfall totals, we're still getting them. But let's take a look at some of those because they are pretty extraordinary, aren't they?

PAUL HUTTNER: Yeah, remarkable stuff. We had a couple of 8-inch-plus reports basically centered on the western edge of Duluth. And we got that 9-inch report in the Duluth Denfeld neighborhood earlier today. Then we got a 9.93-inch report from a train spotter in the Two Harbors area.

And then just coming in the last hour or so here, about an hour ago, 10.10 inches from a National Weather Service employee, 4 miles northeast of Duluth. So just on the northeastern edge of Duluth. Over 10 inches of rain.

TOM CRANN: In what period are we talking there? 24 hours?

PAUL HUTTNER: No, less than that. We're talking about from, I think, 6, 7 o'clock last night up through maybe 9, 10 o'clock this morning. So more like 12 to 14 hours. I think that will end up being one of, if not the, highest rainfall totals 24 hours ever recorded in and around the North Shore.

TOM CRANN: Now, the rain, it looks like at this point, has all but tapered off for the area.

PAUL HUTTNER: Yeah, it has, for the most part. There's a few showers that are still going to make their way through the Duluth area tonight. But they're very light. And they're fleeting. They're moving quickly. The front is coming through. So the threat for heavy rain, Tom, pretty much turned off now in the Duluth area. That's the good news.

TOM CRANN: All right. That's good news. But it does not mean that the swollen rivers, the Saint Louis, for example, and others are then on the decline, right?

PAUL HUTTNER: Right. And that's an important thing to note with flooding and flash flooding. Even though the rains have stopped, all that water still making its way down into creeks, down into rivers.

Now, the smaller creeks and rivers that were raging so quickly earlier today, they're going to be the first ones to drop as that water runs off. But all that water is either going into Lake Superior, or it's going into bigger rivers.

And in this case, the Saint Louis River, which we now have a new record and even a new total from the last time I talked to you. It's now up to 16.14 feet. The record was 15.8 feet that was set 62 years ago. That's the Saint Louis River at Scanlon. So this will be the flood of record for the Saint Louis. That river is still rising at this hour, Tom.

TOM CRANN: And that is an increase of a foot from when we talked, what, two hours ago?

PAUL HUTTNER: It is. So it gives you an idea of the force of this water as it's come through the area. Looking at the pictures and everything we've heard today, I think this is going to be-- it's safe to say this will be multimillions of dollars in damage. We're going to remember this flood in the Duluth area for a long, long time to come.

TOM CRANN: All right, Paul Huttner, Thank you for covering it for us. I appreciate it.

PAUL HUTTNER: Thanks, Tom.

TOM CRANN: That's our chief meteorologist, Paul Huttner. There is a lot more online at mprnews.org from Paul, especially on the Updraft blog. We've had a live blog running all day as well.