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Climate Scientists Explain Ins And Outs Of Idaho’s Wild Winter This Season; No Drought Areas In NW
Posted on Friday, May 19, 2017 (PST)

If it seems the winter was unusual, that’s because it was and continues to be, at least in Idaho, according to three climate scientists who spoke to the Northwest Power and Conservation Council at its meeting in Boise this week.

 

“This is one of those winters that has been far outside the norm,” Jay Breidenbach, warning coordination meteorologist with the National Weather Service in Boise, told the Council.

 

“Snow is important to Idaho and is part of our resources,” adding that there was plenty of the white stuff this winter, which is still falling at higher elevations in northern Idaho, and many of Idaho’s rivers are at flood stage.

 

Across the nation, he said, 20 weather events had damages of $1 billion or more, and the onion industry suffered more than $100 million in damages when storage buildings collapsed under much higher than normal snow accumulation in eastern Oregon.

 

Almost all of December 2016 and January 2017 had temperatures that were below normal and that contributed to the accumulation of low-level snow, Breidenbach said.

 

“Nine inches of rain is normal, but we’ve had 13.28 inches in the Boise River basin so far this water year (the water year began October 1, 2016). 20 inches of snow is normal, but we have had 39.1 inches,” he said. “We could have predicted this to a certain extent, but we couldn’t have predicted these extremes.”

 

Ron Abramovich, water supply specialist, Natural Resources Conservation Service, Breidenbach and Troy Lindquist, senior hydrologist of the National Weather Service in Boise described a cold winter with rain, snow, high river flows and far higher than normal water supply forecasts in most Idaho river basins during a winter that began with big rains in October 2016.

 

“October was an awesome month for precipitation at 200 to 400 percent of normal,” Lindquist said.

 

Spokane in eastern Washington, a dry area of the state, had over 6 inches of rain, which is a record dating back to 1881. Northern Idaho had 15 to 20 inches of precipitation.

 

“If you need to recharge after a drought, this is an excellent way to start a new water year,” Lindquist said.

 

It began when the typical jet stream that comes out of Russia and the Aleutian Islands and heads across Canada shifted to the south. Before that, the early water supply forecasts were not much higher than normal, he said.

 

Last year a strong El Nino produced above average temperatures and later a La Nina set the stage for a cold and wet winter this year.

 

“When you go directly from an El Nino to a La Nina, there is a lot of energy to dissipate,” Abramovich said. “Now, we’re still a month and a half out before we lose our snowpack.”

 

“We’re not forecasting the wettest winter on record, but it’s close,” he said.

 

After a dry year, record high precipitation in October “primed” the soil in Idaho and that was followed a couple months later in February, which again had record high precipitation, with nearly all SNOTEL sites receiving precipitation that was at least 200 percent of normal and many over 500 percent of normal.

 

“February changed the water supply outlook for the year,” Abramovich said.

 

In fact, all across the Northwest October to April was consistently in the top 10 percent of high precipitation years and some areas set records. Even on May 16, 2016, the day the three climate scientists spoke to the Council, the snow water equivalent across about one-third of the Northwest was still 150 percent of normal or more.

 

Much of the precipitation had to do with what the three called atmospheric river events. Some 45 such events occurred this winter along the west coast. California needed just five to move beyond its drought, Abramovich said.

 

The bottom line is that there are no areas of drought in the Northwest at this time and the region is experiencing the best water supply outlook since 2011, he said.

 

Many of the Idaho and eastern Oregon storage reservoirs are full.

 

Winter snows are sticking around longer than normal, Abramovich said. In the Boise River basin this week, some 22 percent of the basin still remains under snow, a far cry from what the area experienced in 2015, when water off the West Coast was the warmest in 60 to 70 years.

 

The Boise River is at flood stage and just 30 cubic feet per second from record high flows. Since March 1 the amount of snowfall in the Boise River basin has been the eighth highest since 1961, and for the first time in years the basin will have a surplus of water, which provides a “carryover” of water supply for next year.

 

The Big Lost River Basin in Central Idaho, which had received a year’s worth of precipitation by February, is the best since 1997 or 1995.

 

And, most water supply forecasts in the Columbia River basin are in the top five best on record.

 

For the scientists’ presentations, go to https://www.nwcouncil.org/media/7491095/7.pdf

 

Also see:

 

--CBB, May 12, 2017, “Heading Into Summer Water Supply Forecasts Across Columbia Basin Above Normal; Once Of Wettest Years,” http://www.cbbulletin.com/438902.aspx

 

--CBB, April 14, 2017, “Big Water Mainstem: Runoff Supply Forecasts Continue To Rise At Columbia, Snake River Dams,” http://www.cbbulletin.com/438713.aspx

 

--CBB, April 7, 2017, “2017 Runoff: Central Idaho’s Deadwood Summit gets 147 Inches Snow; Sees Five Times Above Normal,” http://www.cbbulletin.com/438672.aspx

 

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