Milder days ahead: Flood updates, La Nina fades

Old man winter has been a grumpy old bear this year, but he’s showing signs of easing up the next few days.

A change in the jet stream to a more “zonal” flow (west to east) will bring increasingly mild Pacific air masses to the Upper Midwest in the next week.

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Modles indicate several days in the 40s ahead. (Click to enlarge)

One critical factor in the magnitude of our warming trend over the next week is the amount of snow cover in Iowa. There are only a couple of inches in most of Iowa, and much of that may be gone later today or on Friday.

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Snow depth: Bare ground to the south!

As warmer southerly breezes blow in from Iowa over the next week, they will have less time to “modify” over the snow covered areas of southern Minnesota. That will mean increasingly milder air in the days to come on days when we have a south wind. The first “test” of that theory will be Friday, when a milder southerly breeze will blow in from Iowa.

How warm will it go? The forecast NAM 850 millibar (5,000 foot) temp at MSP Airport is about +4 degrees C Friday afternoon. In late spring with no snow on the ground that would yield a “potential” temperature of around 60 degrees under sunny skies and ideal conditions.

With deep snow cover, the air mass will modify and cool accordingly Friday…but I still think it’s possible temps should soar well into the 40s Friday in southern Minnesota, and I would not be stunned to see a 50 degree reading somewhere in southern Minnesota, maybe close ot the metro… Friday afternoon.

After an abrupt cool down into the 30s this weekend behind a cold front Saturday, I do expect temps to recover into the 40s again next week, with another shot at 50 not out of the question as snow cover begins to melt .

Flood update today:

The NWS issues updated flood outlooks on Thursdays. As the snow melts at an increasing rate in the next week, we should start to see some rivers respond with rises.

The big factor in flood potential is snow water equivalent (SWE) still trapped in snowpack and the top layer of soil. As you can see from the NOHRSC map below, there is still agood 6″ to 8″ of liquid water equivalent available as “runoff” once the snow melts in the Minnesota and Red River watersheds.

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Also note the 12″+ SWE around the BWCAW in northeast Minnesota. Lakes should be high and rivers in the BWCAW, and along the North Shore should be raging this spring.

You can see today’s flood outlook updates below.

-Twin Cites NWS (Minnesota, Mississippi, St. Croix % Crow Rivers)

-Grand Forks NWS (Red River)

If you think weather forecasting is complicated, try a career as a hydrologist. They use complicated models with sometimes sparse and incomplete data (sounds familiar!) from snow cover analysis and river gauges. Flood forecasting is a science all it’s own, and I have a ton of respect for the hydrologists who work hard to keep us ahead of the curve with rising river levels in flood season.

If you’ve ever had a tough time deciphering those “probabilistic outlooks” check out this excellent explanation from the Grand Forks NWS web site.

Flood radio show:

You can hear a special flood radio show from the NWS La Crosse tonight from 7-8pm here. Here are some of the topics NWS La Crosse will cover tonight.

Spring Flooding Live NOAA Weather Radio Show – March 10th (7-8 PM)

With so much concern regarding spring flooding, Mike Welvaert (Hydrologist) and Jeff Boyne (Forecaster) will be hosting a live NOAA Weather Radio show dedicated to this topic on Thursday, March 10th from 7 PM to 8 PM. Subjects to be covered include:

Why the flooding potential is so elevated this spring;

A look back at the April 1965 Mississippi River flood;

Spring snowmelt flood forecast for the local area.

In addition, they will be answering questions pertaining to flooding. These can be e-mailed either before or during the show by using the following e-mail address: Jeff.Boyne@noaa.gov. They will also be taking phone call questions during the broadcast. The phone numbers to be used will be provided during the show.

La Crosse wins “golden snow shovel.”

Our rather wimpy Wednesday snowmaker did manage to crank out an impressive 6.2″ of snowfall at the La Crosse NWS office. Congratulations (condolences?) La Crosse, you win the golden snow shovel award with the latest weather system. There were some respectable snowfall totals for southeast Minnesota, northeast Iowa and Wisconsin.

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Wednesday’s snowfall map. (Click to enlarge)

La Nina fades:

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Today’s latest ENSO diagnostic discussion highlights the now fading la Nina in the tropical pacific. Forecasts call for a likely return to “ENSO neutral” conditions by summer. This could mean our spring like weather may be closer to “average” in the Upper Midwest…which means, expect a little bit of everything with wild swings in temperatures and periodic storms.

What else would we expect in Minnesota?

PH

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