Tuesday, January 2, 2018

Snowpack below normal across Idaho


Ron Abramovich measures water content of snow at More's Creek Summit

More Winter Storms needed to reach normal levels

Idaho City–More’s Creek Summit has just 18 inches of snow, that’s just half as much snow as last year according to the Natural Resources Conservation Service.

“We averaged just 6.3 inches of water today. We’ve been measuring this snow course since 1932 and 12 inches of water is the average. Today we measured 25 inches of snow, but the average is 52 inches of snow,” said NRCS hydrologist Ron Abramovich.

Even though the National Weather Service detected La Nina conditions in the Pacific Ocean last fall, Idaho’s precipitation levels are well below normal December levels according to Abramovich.

“We were off to a good start. We had October rains but then we had a rain in November that melted snowpack at this elevation. Our higher snowtel sights kept the snowpack and their totals are much better. Right now our snowpacks in Western Idaho are just 68 percent of normal,” said Abramovich.

December snow survey shows current snowpacks in Idaho are 45-80% of average but the snowpack in the Idaho backcountry now accounts for just 20% the season total and the mountains are still collecting snow well into May.

“Strong LaNina weather patterns suggest over the years that we will have a catch-up period from late January into February and continuing into the spring," said meteorologist Coleen Haskell. "In terms of water supply, I think we’re just getting started. There’s the LaNina perception is that it should have started earlier. Some might think that the weather is underachieving, but it just began."

NRCS Snow surveys are conducted at the end of each month from December through May to make snow runoff predictions and water supply forecasts used in managing Idaho’s water resources.

“I’m not concerned with these snowpack numbers,” said Abramovich. “Last year the bulk of our snow came in February and March so we’re waiting to see if the La Nina weather pattern kicks in. Currently, the snowpacks across the state are shallow but we’ll have a better look next month. We still have two-thirds of winter catch up,” said Abramovich.

November, December, and January are generally Idaho's biggest precipitation months, but November and December did not come through. November precipitation amounts were only 20-30% of average across southern Idaho and 40-60% in central and northern Idaho. December temperatures were very cold at many of Idaho’s SNOTEL sites but precipitation ranged from 45% on average to just above average in Eastern Idaho.

“But its very much a different LaNina characteristic this year,” said Haskell. “But keep in mind that they are both LaNina, it just depends on how the atmosphere is responding. In weather terms that means that there is a high-pressure ridge that sat over us the past few weeks. It has blocked all of the weather and deflected storms up North into British Columbia. But it will start breaking down and we’ll start seeing storms again.”

Abramovich says there’s a lot of winter ahead of us.

“The water supply picture will hopefully improve,” added Abramovich. “Above average precipitation will be needed for the next three months to reach average snow water content amounts in the mountains by April,”

The highest snowpacks are 75-80% of average in Eastern Idaho. The lowest snowpacks are 45-55% of average in the Little Wood, Willow, Blackfoot, Portneuf and Bear basins, as well as the Owyhees. Elsewhere, snowpacks are 58-68% of average.





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