Warm temperatures and forecast rain on snow at higher elevations are expected to bring minor flooding to residential areas near the Big Wood River this week.
“We’re expecting the river to peak early on Friday evening,” National Weather Service meteorologist Jack Messick said Tuesday.
Messick, based in Pocatello, said river depth at the Hailey gauge was expected to rise from 4.64 feet Tuesday to a 5.34-foot crest Friday. A gradual decrease in flows for several days afterward is expected, with the river subsiding below flood stage by May 18.
“Persons near the river should be aware of the expected high water and take action to protect property,” the Weather Service stated in a news release.
Messick said this peak will result from a combination of rain on snow and some snowmelt.
“There could be major flows through Memorial Day weekend, so this may not be the best year to be on the river early,” he said.
Hailey Police Chief Jeff Gunter said the Draper Preserve is closed until further notice. War Eagle Drive is closed to nonlocal traffic.
There was minor flooding on both sides of War Eagle Drive on Tuesday, Gunter said.
“That’s expected to increase over the next few days,” he added.
Gunter said he has noticed that a warm day will generally produce higher water at about 3 a.m. the following morning.
According to the National Weather Service, at 5 feet the river would create street flooding along Cedar, War Eagle and Della Vista drives in the lower subdivisions in Hailey, and in Riverview Drive in Bellevue. Water would also be over some secondary roads in west Ketchum (Wood River Drive). Gimlet subdivision would have flooding issues also.
Later into the weekend at elevations above 8,500 feet the mountains will be receiving snow, Messick said.
As of Tuesday, the snowpack in the Big Wood drainage was 94 percent of normal.
On Monday, the Hyndman snow-telemetry site at 7,620 feet elevation reported that the snowpack’s water equivalent was 11.5 percent of the peak amount, which was recorded on April 9. The Galena Summit site at 8,780 feet elevation had 60.83 percent of the peak snow-water equivalent remaining, while the Dollarhide Summit site at 8,420 feet elevation had 58.47 percent remaining.
If the weekend storms bring a major dump to the mountain, things could change.
“That could throw a wrench into our expectations,” Messick said.
He said the usual time for a final peak flow in the Big Wood River is between mid-May and early June.
The city of Hailey has posted flood preparation information, notification options and sandbag pile locations on its website at haileycityhall.org.