Disappearing Great Lakes Ice; Thawing soils soak up rain; 1st 70 Wednesday!

79% less winter ice cover on Lake Superior since 1973!

71% overall reduction in winter ice cover on the Great Lakes

.25″ to .50″ rainfall Monday at many locations

Soaking in rain soaking in now in southern Minnesota as soils thaw in top few inches

44 degrees 6 – inch soil temperature at Albert Lea & Redwood Falls!

Venus-Jupiter conjunction this week- best in years!

Disappearing Great Lakes Ice!

It’s no surprise to anyone who’s lived on the North Shore for decades that there’s less ice on Superior than there used to be.

What’s surprising is how much less.

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A satellite photo of Lake Superior taken Friday afternoon shows little ice on the lake. (Photo by NOAA/ Space Science and Engineering Center, University of Wisconsin-Madison via Duluth News Tribune)

A recent study in the Journal of Climate tags a 79% decrease in the coverage of ice on Lake Superior since 1973. Overall the Great Lakes are sporting 71% less ice in winter.

Temporal and Spatial Variability of Great Lakes Ice Cover, 1973-2010*

Jia Wang

NOAA/Great Lakes Environmental Research Laboratory, Ann Arbor, Michigan

“There was a significant downward trend in ice coverage from 1973 to the present for all of the lakes, with Lake Ontario having the largest, and Lakes Erie and St. Clair having the smallest. The translated total loss in lake ice over the entire 38-yr record varies from 37% in Lake St. Clair (least) to 88% in Lake Ontario (most). The total loss for overall Great Lakes ice coverage is 71%, while Lake Superior places second with a 79% loss.”

The data comes from satellite and Coast Guard observations between 1973 and 2010.

The data did not include this winter, when a paltry 5% of the Great Lakes froze over.

Compare that to 94% in 1979, and a longer term average of 40%.

Why do we care?

So less ice on the Great Lakes is a good thing right? Well yes and no.

-It may help extend the shipping season, but it also exposes more surface water to evaporation in winter which can reduce lake levels.

-It may also increase winter wave action and shoreline erosion.

-With more of the lake open in winter, lake effect snowfall can actually increase during cold air outbreaks. Ice cover reduces lake effect snow.

What’s causing the changes? That’s the 64k question of course. Likely suspects include ENSO cycles, AO phases and yes, climate change.

Here’s more from the Duluth News Tribune:

1st spring soaker!

Monday’s rainfall was a precious .25″ to .50″ at most locations. It was especially precious because it soaked into drought parched soils in southern Minnesota.

(click image to enlarge!)

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The weekend warm spell thawed soils in southern Minnesota. A check of real time soil temps at southern Minnesota locations Monday PM shows several spots well above freezing at 6″ soil depth.

Albert Lea 44 degrees

Redwood Falls 44 degrees

Marshall 39 degrees

Mankato 34.5 degrees

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A look at the soil temp plot for Waseca at various depths shows the trends.

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So the rain we got Monday is soaking into the top few inches of soil from the Twin Cities south. That’s great news. Soils are still basically frozen west and north of the metro.

Sky Show this week! Best Venus/Jupiter conjunction in years

No doubt you’ve already seen the awesome sight in the western evening sky as bright Venus snuggles up with Jupiter after sunset.

You can’t miss the two on clear nights. And you should be able to see them the rest of the week in the west after the clouds clear starting on Tuesday.

On Thursday night, the conjunction of Venus and Jupiter will be the closest in years.

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  • kurt nelson

    I would add an additional concern with the lack of lake ice on Superior and evaporation. The watershed for the lake is relatively small, small enough that snow and rainfall keep equal with evaporation on a normal year, but on a low snow/rain year, evaporation can exceed input, and this is a problem.

    Many assume the watershed for Superior must be huge to support such a large body of water, but this is just not the case. Without the albedo effect from lake ice, evaporation is increased, and temperatures raise, none of which is great for the lake, watershed, or state.