Second flood surge moving down Minnesota River

Minnesota's complex watersheds and hydrology are making for challenging flood forecasts this spring. Right now, some rivers are still basically steady and frozen up north. Some rivers are rising rapidly. And some rivers have already crested and are starting to fall.

You can check the latest river levels here in real time.

Minnesota: Land of many watersheds 

Minnesota is an interesting state when it comes to watersheds. Minnesota sits on a high point in the center of the continent. That means water runs away from Minnesota in multiple directions.

Most of the rain or snow that falls in Minnesota and runs off travels south through the Mississippi watershed. But some also run north out of the Rainy and Red River basins. A small area in southwest Minnesota drains into the Missouri River. Water from Minnesota eventually flows into the Gulf of Mexico, Hudson Bay and the Atlantic Ocean via Lake Superior through the other Great Lakes.

Very little water flows into Minnesota. A small part of the eastern Dakotas drain into the western Minnesota River basin.

Minnesota is a big net water exporter.

Flood forecast challenge: Uneven snowfall and melt rates

Uneven snowfall and melt rates are producing some complicated runoff patterns this spring. That's challenging for hydrologists making flood forecasts. Our initial warmup melted snow across southern Minnesota first. Rivers like the Cottonwood near New Ulm surged meltwater into the Minnesota River. Then as the snow vanished, meltwater rates have slowed.

See how the Cottonwood at New Ulm is now steadily falling?

The lower upstream inflow means the Minnesota River has already crested once and is now falling at locations like Henderson southwest of the Twin Cities.

More snow upstream

The snow cover map for Minnesota tells a big part of the flood story. See how the snow is gone across south-central Minnesota? That's why rivers like the Cottonwood are now falling. But there's still melting snow in western Minnesota that is flowing into the upper Minnesota watershed.

Upstream water levels on the Minnesota River are rising quickly at locations like Montevideo.

So it looks like we may see a second crest on the Minnesota River at some locations as that next surge of floodwater moves down the river toward Mankato and eventually the Twin Cities.

That's one reason the Mississippi River at St. Paul and downstream is forecast to stay high for the next week.

Forecast: Mostly good news

This is the 13th day of basically dry weather in most of Minnesota. The Twin Cities has logged just 0.1 inch of precipitation since March 10.

The good news in the (flood) weather forecast is that our dry pattern will likely continue through most of next week. NOAA's GFS model put out just .14 inches of precipitation through April 7. That's ideal for keeping river levels from pushing even higher than currently forecast. There are signs that we could turn wetter after that. That might be late enough to avert additional flood issues in southern Minnesota. But it could potentially boost levels on the Red River.

Today will be the warmest day (and first 60-degree day) since Oct. 22, and the warmest for the next week at least.

Stay tuned.