Rising temps, rising waters

By Justin Post - 05/16/2008

Increased temperatures this weekend probably will cause some streams and creeks in southwest Montana to rise over their banks, according to the National Weather Service.

The area’s larger rivers, on the other hand, are not expected to reach flood stage at this time, according to weather people.

“Right now our biggest concern is the smaller streams,” said service hydrologist Gina Loss. “There is a lot that is going to pour out once we get these warmer temperatures. It’s going to really start throwing water into those smaller tributaries.” Rivers in southwest Montana are expected to rise early next week, but the weather service does not anticipate enough water to create the flooding projected for other areas of the state, she said.

“The situation bears watching,” Loss said.

The Big Hole River, for instance, was running at 3.25 feet Thursday at Melrose and is expected to rise to roughly 3.8 feet by Sunday, Loss said.

That is still more than 2 feet below the stage where flooding occurs and the weather service does not foresee main stem flooding at this time.

That’s not the case in western Montana and north central Idaho where “quite a few” main stem rivers will be approaching or exceeding flood stage beginning this weekend or next week, weather service warning coordinator Peter Felsch wrote in an e-mail this week to emergency responders.

Those areas have more snowpack than southwest Montana, Loss explained.

She pointed to the Jefferson and Upper Clark Fork river basins where an estimated 15 inches of water remains in mountain snowpack.

That’s significantly less than water holding in other river basins such as the Gallatin, 23 inches; Kootenai, 28 inches; Flathead, 26 inches; and Bitterroot, 24 inches.

“We just don’t have as much snow to pull off as they do,” Loss said.

Even so, rain combined with warm temperatures would increase the potential for flooding in southwest Montana, she said.

“The good news to the whole event is we aren’t expecting any rain through the weekend, which would definitely complicate things,” Loss said. “It would be horrible.” Runoff traditionally begins in early to mid-April and is about a month behind schedule this year, she said.

Roger Ebner, Butte-Silver Bow’s emergency management coordinator, said he is monitoring the runoff and has met with weather service officials about the issue.

“There is some activity in western counties; they have a different situation than we do,” he said. “There are no projections for flooding in the Butte-Silver Bow area.” Ebner notified police, fire and Red Cross Thursday that a potential for flooding still exists in the area with rapid melting and rising streams.

“We have weekly meetings and our emergency response community has been put on an advisory notice,” he said.

In Butte, police are being asked to monitor Blacktail and Silver Bow creeks while on patrol and report any significant or sudden increases, Ebner said.

— Reporter Justin Post may be reached via e-mail at justin.post@lee.net.