A new round of high lake levels and stream flows is expected this week as warm weather causes high mountain snow pack to melt.
National Weather Service forecasters are calling for another warm day today with highs in Spokane and Coeur d’Alene approaching 80 degrees.
The summer-like weather is not going to last. A pair of low pressure systems are going to bring chances of thunderstorms this afternoon and Tuesday and then possible heavy rain on Tuesday night and Wednesday, which could aggravate flooding in some areas, forecasters said.
“We are looking at a pretty good hydrological event later this week,” said Jon Fox, during a weather service briefing this afternoon.
Some of the heavy rain may fall in southern British Columbia and western Montana, which feed into the Kootenai and Pend Oreille river systems.
Lake Pend Oreille is expected to reach flood stage next Monday, and the Pend Oreille River at Newport may rise to 2,050.3 feet, which is two feet above flood stage.
The Moyie, St. Joe, Okanogan and Snake rivers may also rise to or above flood stage.
Katherine Rowden, weather service hydrologist, said warm weather in recent days could contribute to a snow melt of as much as four inches of water equivalent. Some mountain areas still have as much of 70 inches of water in the snow pack.
“There is still a lot of high-elevations snow,” she said.
Lake Pend Oreille was at 2,062 feet in elevation this morning, just below flood stage at 2,064 feet. It is expected to slowly rise this week.
The Kootenai River at Bonners Ferry was at 61.9 feet and expected to rise near its flood stage at 64 feet later this week.
Late spring snow melt typically affects the larger river systems in the region.
The Spokane River was flowing at 27,000 cubic feet per second today and expected to remain below flood stage. Lake Coeur d’Alene may rise by a half foot, but also stay below flood stage, forecasters said.
Cooling weather may help ease flood problems.
Highs could drop to the lower 60s on Wednesday before rebounding to the 70s later in the week.
The chance of showers is about 50 percent this afternoon and 40 percent tonight, rising to 50 percent on Wednesday. There is also a chance of thunderstorms later today
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