Mega Chinook: 50% of USA snow cover gone in 3 days!

What a difference a week makes.

Just last week winter blasted the big chunks of the USA with ice and snow. Today it looks and feels like springtime in much of the nation.

A surge of mild air has rapidly melted much of the snow cover in the nation. Three days ago 63% of the USA was covered by snow. Today that number has melted away to just 32%. Roughly half of the USA surface area covered by snow has melted in just the last 3 days!

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NOHRSC snow depth on Friday February 11th shows 63.1% of the USA covered by snow. (click images to enlarge)

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USA snow cover dropped dramatically to just 32% of the USA Monday.

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Check out this amazing animation of snow cover growing and then rapidly melting on the USA in the past two weeks. (Hint: Set the animation rate at around 30 for a quicker loop)

70s in Nebraska!

The Chinook fueled warmth caused high temperatures to surge into the 70s as far north as western Nebraska Sunday.

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Sunday’s high temps. (Click to enlarge)

“Snow free zone” approaches Minnesota:

The weekend warmth pretty much destroyed snow cover as far north as a Pierre, SD to Omaha line. There are big holes now in the snow cover in Iowa, and as little as 2″ on the ground in north central Iowa not far from the Minnesota border. There may be some snow free bare ground in parts of Minnesota this week!

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There’s still plenty of snow in northeast Minnesota and along the Minnesota River Valley in southwest MN and in the eastern Dakotas. It will be interesting to see where we are at week’s end with more 40s in the forecast. It will also be interesting to see if river stream gauges begin to spike this week as runoff is released into watersheds.

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All quiet for now on the Red River at Fargo.

Do “Atmospheric Rivers” trigger massive floods & snowstorms?

We’re learning about new features in the atmosphere all the time. Just as medical imaging is giving new insights inside the human body, remote sensing is giving meteorologists a better understanding of previously unseen features in the atmosphere.

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From NOAA:

“Atmospheric rivers are relatively long, narrow regions in the atmosphere – like rivers in the sky – that transport most of the water vapor outside of the tropics. These columns of vapor move with the weather, carrying an amount of water vapor roughly equivalent to the average flow of water at the mouth of the Mississippi River. When the atmospheric rivers make landfall, they often release this water vapor in the form of rain or snow.”

Check out the full NOAA release on “atmospheric rivers” here.

National Severe Storms Lab gets new Director:

There’s a new Sherriff at NOAA’s NSSL.

“Steven Koch spent time in Norman, Okla., while he earned his doctorate in meteorology in 1979. He’ll return to Norman in late April as the new director of NOAA’s National Severe Storms Laboratory, the laboratory most involved with tornado research.”

Warmth returns Tuesday:

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You’ll notice the wind will be a little milder Tuesday through Thursday as the next surge of milder air pushes in from the south. Temperatures may spike into the 40s again, as we continue to melt snow in “The Great Snow Eater of 2011.”

Look for a sharp cold front to drop temps back to seasonal levels (20s) Friday & Saturday. There may be some light snow with the front Friday…and perhaps a better chance of accumulating snow by next Monday.


  • Curmudgeon

    I could understand the non-stop, egregious use of words like “mega” that seem to pepper nearly every Updraft blog entry if MPR were a commercial site that needed to pander to advertisers. But a snowmelt in February is hardly newsworthy, much less the subject for banner headlines. Mildly interesting perhaps, to see how this frequent event plays out, but hardly shocking or worth superlatives.

    The news media today seems to have traded good sense for exclamation points, gravity for fluff. We are all to be forcibly entertained rather than informed. Our sense of normalcy now only exists in a state of constant pseudo emergency.

    I do enjoy the content I find on Updraft, particularly of global warming, and regret that I have to constantly filter out the detritus of media excess. I hope that when you emerge into your later years you do not regret having added to the burden of sensationalism with your current high-pitched approach to reporting on this inherently interesting subject.


  • Optimist

    You picked the right nickname, Curmudgeon. I think that PH is simply enthusiastic about his profession. And because he’s talking of continental and global scale movements of air, water, and heat, terms like “Mega” are appropriate.

    I agree that much of what appears in the media is both uninformed and excessively hyperbolic in its tone. But I don’t think you can tar Updraft with the same brush.

    — a computer engineer in Cannon Falls

  • bwhite

    I find it fascinating that a chinook effect (which I had previously thought to be a highly localized phenomenon) can help reduce nationwide snow cover by 50% in such a short period of time and I support Paul’s enthusiasm in conveying this science to us. I appreciate the readily understandable, scientifically rigorous content that is regularly presented on this blog and can only wish that more of us were as passionate about science!

    -a geology grad student in Minneapolis