Ag Weather Forum

Snow Cover Starting in Western U.S.

Bryce Anderson
By  Bryce Anderson , DTN Senior Ag Meteorologist
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Over a foot of snow is noted at the tops of the Sierra Nevada mountains. Snowpack is a little heavier in the northern Rockies and northern Cascades. (Photo courtesy of Amber Tanaka)

Western U.S. mountain snowpack -- especially in California -- is being closely tracked this fall and winter for potential drought relief. Mostly of California is still in an Extreme to Exceptional long-term drought according to the U.S. Drought Monitor.

USDA reports do indicate some snow is starting to pile up. As of the end of October, a USDA water report notes that "High-elevation snowpack has begun to accumulate in the mountains of the West ... The northern Cascades and northern Rocky Mountains have over 2 feet of snow in the higher elevations, whereas the Sierra Nevada snowpack is over 1 foot at the

highest peaks. The central and southern Rockies have been warm and dry and are reporting a few inches of snow depth in the south to nearly 2 feet farther north in the Grand Teton Mountains of western Wyoming."

Some of those numbers sound promising, but don't' get your hopes up much yet. Mountain areas of the western U.S. that are looked upon as key locations for snowpack have less than 25% of the median snowpack on the ground right now. With temperatures forecast to run above to much-above normal during the next week to 10 days, even the locations with heavier snowpack now are quite possibly going to be in a deficit category here in early November.

Looking further ahead, longer-range forecasts for the winter season have heaviest precipitation -- meaning mountain snowfall -- indicated for the northwestern U.S. south to northern California (approximately north of San Francisco). If that indeed verifies, irrigation water would be in more favorable supply for the 2017 crop year in the Far West.

One big, big area for snowpack -- Colorado -- has not shared in the recent snowfall development. Almost all snowfall stations in Colorado have near zero for snow at this point. With high temperatures of at least 60 degrees Fahrenheit, it's no wonder that the powder has not started "naturally occurring." For central U.S. ag, the Colorado snow pack is key for its supply of water to the Colorado River basin, along with the Platte River and Arkansas River basins.

The evolution of the winter pattern for snowfall, but also temperatures, will be closely tracked. Recent years of warmer weather means that snow does not stay as long during the subsequent growing season. That affects irrigation supplies, but also interferes with diurnal temperature variances that can produce thunderstorms and provide a timely midsummer moisture shot to crops.

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