Winter storm watch: Water released from Friant Dam; Yosemite closure a possibility

After a one-day reprieve on Friday, a “Pineapple Express” tropical storm should roar through the central San Joaquin Valley this weekend, bringing heavy rain to the Valley floor and foothills, and snow to higher mountain elevations.

“It’s going to be packing a big punch with lots of moisture,” said Scott Rowe, a meteorologist at the National Weather Service office in Hanford.

Around the region preparations were being made for the weekend storm, which could drop 1 to 3 inches of rain on the Valley and more in the foothills. The warm storm should raise the snow level to above 7,000 feet. But high elevations could see 6 to 8 feet of snow.

Yosemite National Park officials were on alert for potential flooding of the Merced River at the Pohono Bridge, which could cause a park closure.

But as of Thursday afternoon, no decision about closing Yosemite had been made, said park spokeswoman Jamie Richards.

“There is concern of flooding,” she said. “We are watching the levels of the river.”

The potential for the Merced River to flood has some recalling the flood of 1997, when it crested above 23 feet. Rowe said the forecast shows the river could reach the flood stage of 10 feet sometime Saturday and could crest at just under 16 feet Sunday afternoon.

On Thursday afternoon, the river was at 4 feet, Richards said.

Wednesday’s storm dropped 2.9 inches of rain in Yosemite Valley; Oakhurst got a whopping 4.46 inches.

The storms brought Fresno’s seasonal rainfall total to 5.20 inches, about 1.5 inches above the seasonal average total of 3.76 inches.

Water was gushing out from Friant Dam in a controlled release that began Tuesday. Millerton Lake was 73 percent full on Thursday at 378,000 acre feet.

An initial release of 220 cubic feet per second was increased Thursday to 3,000 and would go up to 5,000 cfs, said Michael Wolfe, hydrologic supervisor at the dam.

At Hume Lake, rangers were monitoring water levels at the dam, said Carol Hallacy, district ranger for the Sequoia National Forest. Water was 6 feet from the top of the dam Thursday afternoon, she said.

The overflow from the dam would go into the Kings River, which dumps into Pine Flat Reservoir. Rick Brown, spokesman for the U.S. Army Corps of Engineers, said Pine Flat has room for water. On Thursday it was 29 percent full at 290,000 acre feet. By contrast, in the 1997 flood, Pine Flat was at about 900,000 acre feet, he said.

The release of water from Friant Dam into the San Joaquin River should not cause downstream flooding, said Maury Roos, chief hydrologist-retired at the California Department of Water Resources’ flood-management division. The San Joaquin River’s downstream capacity is 8,000 cubic feet per second, he said.

However, flooding is likely in smaller creeks coming out of the foothills on Sunday, Roos said.

Flash-flood warnings for the foothills and Sierra Nevada were issued for the weekend and would remain in effect through Monday afternoon, Rowe said.

Jerald Meadows, a spokesman for the National Oceanic and Atmospheric Administration, said weather forecasters will use the hashtags #CAStorm and #CAFlood when posting information on social media about the storm and any flooding.

“We ask you do the same when posting updates or photos of impacts so we can easily track and log impacts through these events,” he said Thursday in an email.

A flash flood warning for southern Tulare County and northern Kern County was issued Thursday morning by the National Weather Service. Radar indicated 5 to 9 inches of rain had fallen from the storm as of 5 p.m. The area around Lake Isabella was getting the brunt of the storm.

Excessive rainfall over areas thinned by recent fires will lead to debris flowing through the White River, Kern River, Poso Creek and Deer Creek drainages, the weather service said.

Runoff, debris flows and rock slides are a concern in areas ravaged by fires – among them the Rough Fire in the Sierra National Forest, Cedar Fire in Sequoia National Forest and the Erskine Fire in Kern County.

“They had vegetation ripped from the areas and that makes part of the soil impenetrable,” Rowe said.

Mike Theune, spokesman for Sequoia and Kings Canyon National Parks, said “this is a storm and we’re preparing for it.”

He urged people to be alert to changing conditions in the mountains.

“Take your time, travel safely, be prepared,” he advised.

On the Valley floor, no widespread flooding problems have been reported, but county officials were geared up for weekend downpours.

“We have sandbags and sand available throughout the county,” said Dario Dominguez, flood control engineer for Madera County.

This story was originally published January 5, 2017 at 7:35 AM with the headline "Winter storm watch: Water released from Friant Dam; Yosemite closure a possibility."