S. Idaho’s record April snowmelt was off charts in Boise Basin

In April, Southern Idaho’s snowpack borrowed a page from “The Wizard of Oz.”

It melted, just like the Wicked Witch of the West.

Buried deep in the Natural Resources Conservation Service’s May Idaho Water Supply Report is a detail about a phenomenon that has never before been recorded in 72 years of data collecting.

The Mores Creek area in the Boise River watershed had its greatest April loss ever: 15.3 inches.

Even more significant, the report said that in the first 42 years of recording snowpack, from 1945 to 1986, there were no years in which 10 or more inches of snowpack had been lost in April.

In the past 30 years, however, we’ve lost more than 10 inches nine times, as measured at the Mores Creek Summit monitoring station near Idaho 21 northeast of Idaho City.

That’s the definition of climate change in Idaho.

April precipitation across the state ranged from well below to well above average, depending on location. Most areas received below average, with the lowest in the Snake River headwaters above Jackson Lake. The continuing influence of El Nino kept Idaho’s southern border, from the Owyhee River to the Raft River basins, high at 112 percent to 150 percent of normal.

“Precipitation amounts received since the start of the water year on Oct. 1, 2015, remains encouraging, with the whole state reporting 92 percent of average or better,” said Ron Abramovich, water supply specialist with Natural Resources Conservation Service. “However, those areas with deficits are worth watching and may not improve much as we move into our dry summer months.”

This story was originally published May 9, 2016 at 3:19 PM with the headline "S. Idaho’s record April snowmelt was off charts in Boise Basin."