Wednesday, March 27, 2013

Update on Star Valley Snowpack

This time of year when much of the snow for the winter season has already occurred, the question arises how did we do?   While snows of significance could still occur in April and even into May in the mountains, chances are the current totals for the winter are indicative of the runoff this Spring.

On Star Valley Ranch the snow amounts from Oct. 1 2012 to March 27 2013  are probably not much below the normal amount.  So far while 14 inches remain on the ground at the observation site  located just north of the Round Barn on the Ranch, the total for the season is 157 inches.  In comparison to the same date last year the total was 162 inches. While the greatest snow depth last winter was almost double this year, 43 inches on 3/3/2012 vs 22 inches on 1/20/2013, the unusually warm March in 2012 had reduced the actual snow pack to just 13 inches vs the 14 inches on 3/27/2013.  The actual Snow Water Equivalent on Star Valley Ranch is 4 inches as of 3/27/13

What really matters in the Spring runoff is the snowpack conditions in the higher elevations.   The Willow Creek SNOTEL site in the Salt Range above Turnerville is at 8450 feet.

Following are the stats for Willow Creek

Snow Water Equivalent  as of 3/27
2010 18.80 inches
2011 35.40 inches
2012 24.40 inches
2013 23.90 inches snow depth 74 inches

2010/2011 was a big snow year, with the greatest snow water equivalent continuing to increase into May reaching 48.80 inches.

Last year by 3/27/2011 the snow water equivalent had about peaked and quickly melted under an unusually warm Spring sun.

This years value of 23.90 inches is 84% of the normal amount.

The long range forecast does not support a wet Spring as occurred in 2011, but hopefully an improvement over last year.

Here is the long range forecasts for both the coming month of April and the 3 month period of April/May/June.







One or two big Spring storms could quickly prove these forecasts wrong in Wyoming, but predictability of any particular storm more than a week or two out is still not possible.

3 comments:

  1. When does it typically start to "green up" in the valley? I'm sure it can vary alot due to snowpack and weather, but is there a time frame that is fairly typical?

    Thanks

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  2. It varies greatly from year to year. As an example by the first week in April 2012 the snow was essentially gone and bulbs were coming up etc. The year before it was another month before the snow pack in the valley was gone. This year looks like the snow pack will rapidly diminish the first week in April and we could have a similar scenario to last year. By the first of May given the long range forecasts it should be greening up fast.

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