The National Weather Service issued the warning Wednesday morning for Boise, Valley, Camas, Adams and Washington counties, as well as northeastern Elmore County and eastern Gem County.
The warning, in effect until 10:45 a.m. Friday, is prompted by a “very moist weather system” expected to move through the area from Wednesday morning through Thursday night, NWS reports.
A milder flood advisory is in effect for parts of the region, including Ada, Canyon and Owyhee counties and, in eastern Oregon, Malheur and Baker counties.
Snow is expected to turn to rain Wednesday night at elevations as high as 7,000 or 8,000 feet, will rainfall totals of 1 to 3 inches, NWS reports.
The combination of rainfall and melting snow is expected to cause flooding of city streets, parking lots, small streams, fields, ditches, and low-lying roads in communities including McCall, Idaho City, Fairfield, Lowman, Cascade, Council, Horseshoe Bend, New Meadows, Cambridge, Ola, Banks and Garden Valley.
The news contributed to Soldier Mountain Ski Area’s decision not to open Thursday. “Skiing is supposed to be fun and safe,” said a post on the Camas County ski resort’s Facebook page.
Idaho 75 over Galena Summit, north of Ketchum, will close each night this week due to the threat of avalanches, the Idaho Transportation Department warned Wednesday afternoon. That threat is aggravated by warming temperatures and possible additional snow and rain.
A flood warning means that flooding is imminent or occurring, according to NWS.