NWS issues new river forecasts; Snow melt “microclimates”

The NWS issued some updated river forecasts Wednesday.

River Forecasts have been issued for Redwood, Cottonwood, South Fork of the Crow, Crow and Chippewa Rivers.

According to the North Central River Forecast Center, there is still too much uncertainty to issue forecasts for other rivers in Minnesota.

From NWS today:

“Too much uncertainty still exists for the Long Prairie, Sauk, Minnesota, Mississippi and St Croix for river forecasts to be issued at this time. As certainty of the snow melt increases, river level forecasts may be issued later this week and into the weekend.”

The latest hydrological outlook gives the latest information on other area rivers.

It’s interesting to me to note that while some of today’s forecasts indicate major flooding by this weekend, I do not see any forecast of floods in “record” territory yet.

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Stay tuned for updates as hydrologists fine tune predictions in the coming days.

Snow melt “microclimates:”

I know, only a “true” weather geek would even think this is cool.

It is interesting to look around the landscape these days and see the wide variations in snow cover left on the ground. In one neighborhood there is bare grass showing up now, and in others such as near Huttner the Weather Lab, there is still deep snow.

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Weather Lab still sporting 14.5″ snow depth in the back yard! For comparison MSP Airport reported 5″ Wednesday morning.

There are a couple of major factors that determine how quickly snow melts in your yard.

Directional slope:

The directional slope of land determines how quickly snow melts in spring. If the slope faces south or southwest, the sun’s rays strike the land surface more directly, and more incoming solar energy is available to melt snow.

If your yard slopes north (like the Huttner Weather Lab) the reflective nature of snow (high albedo) and the effectively lower sun angle has trouble melting snow.

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Deep snow in Weather Lab back yard. Grass by April I hope!

Tree cover:

Density and type of tree cover makes a difference in the rate of snow melt. Dense tree cover blocks solar energy from the sun’s rays, and leads to slower melting.

Coniferous trees have a bigger effect shading the north side, but can create faster melting through the “pine tree effect” on the south side by bouncing the suns rays and warming those areas more quickly. Ever notice how the south side of pine trees is snow free first?

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A little “pine tree effect” on the west side of the Weather Lab spruce trees.

Bottom line?

If your yard faces south and you have few trees, or pine trees on the north side of your yard, you’re going to see the grass a lot sooner.

If like the Weather Lab you slope north and have dense tree cover, it still looks like mid winter in your back yard.

PH

  • David Riggs

    Paul,

    Keep up the good work. I live on the Mississippi near downtown St. Paul and appreciate your ongoing updates about river levels.

    Hey! Is that a hammock in the background of the weather lab’s yard? Do you have a prediction on when you will be using it this spring?

  • Pat

    What if your yard is south facing, but you didn’t get the leaves raked before the first snow fell?

    You get a slimy, brown mess, that’s what! Eeew…

  • Jacob Dyer

    I love this blog! This post is great, I always think of microclimates, especially how it affects plant growth and distributions in natural forests. Anyhow, keep up the excellent posts!