Flooding in Northern Nevada in spring called a certainty
February 25, 2017
For those thinking this winter can't end soon enough, think again.
Come spring, "flooding is a virtual certainty," said Chris Smallcomb, warning coordination meteorologist at the National Weather Service in Reno.
The severity depends on whether the season is cool with little additional precipitation, allowing the mountain snowpack to melt slowly, or if it heats up and the snow disappears quickly.
Smallcomb said snowpack in the upper Carson River basin is now 200 to 250 percent of normal.
"That's a lot of water. It's close to the melt-off of '82-83 when we had flooding and near flooding on the order of weeks," he said.
Smallcomb spoke Thursday during the last session of the three-day 2017 Carson River Watershed Management Forum, hosted by the Carson Water Subconservancy District and Carson River Coalition in the Bob Boldrick Theater at the Carson City Community Center.
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Smallcomb said data from eight weather stations located along the Sierra Nevada mountains shows snowpack is on a trajectory to break the record set in the winter of 1982-83.
"And break it big time," he said.
In the meantime, even mild precipitation may cause additional flooding in the area.
"The saturation of soil in the Carson River basin is at or near records. The ground is just wet, it cannot handle any more water," Smallcomb said. "Even a moderate storm is going to cause more flooding."
He said another atmospheric river, those big ribbons of moisture that stretch across the Pacific ocean, is coming in early to mid-March, but it doesn't look as threatening as earlier ones.
So far, the Sierra region has been hit by 13 atmospheric rivers when the area typically sees 5-10, and only 2-3 in a drought year.
"By any measure this winter is one of the most exceptional winters for California and Nevada," said Smallcomb.
It all started with a record wet October, Smallcomb said, when more than 9 inches of rain were recorded in Tahoe City, 437 percent of normal.
"This is what really moistened up the ground," said Smallcomb.
Then there were heavy rains in December and January saw one storm after another with little of the usual respite in between.
"Theses storms were just boom, boom, boom, one right after another," said Smallcomb.
There's a silver lining.
"The drought is done for now," said Smallcomb. "Even if we have a dry winter next year, we have a lot of money in the bank."