Cold weather and rain hitting the Flathead in the next 24 hours and running through the weekend should slow down snowmelt in the mountains, leading to temporarily decreased river flows in the valley.
According to Chris Gibson, a meteorologist with the National Weather Service in Missoula, the Flathead can expect some “big changes” coming in the weather, including winter weather advisories for parts of the state.
The incoming weather system should drop temperatures to 10 to 20 degrees below normal, Gibson said, meaning in the high 40s and 50s in the valleys.
Northwest Montana can expect rain late Wednesday and into Thursday, followed by the cold front, which should turn the rain into snow.
Gibson said there could be snow in the valleys, but the cold air should slow down the melting snow in the mountains.
“It will be wet without as much hydrologic impact because of cold air,” Gibson said.
Ray Nickless of NWS said there will still be flooding due to rain and snowmelt, with small stream flood advisories for counties in Northwest Montana, including Flathead County.
As the cold air kicks in, the rivers should see some drop off, Nickless said, but they will still be running high.
The Stillwater River in Kalispell is barely under the 7.5-foot flood stage mark and might get to there again on Wednesday night with the rain event, but the cold air will likely bring it back down.
Nickless did not expect any of the stems of the Flathead River to flood this weekend, with the rain bumping it up a little bit but not to flood stage.
The high-elevation snowpack is still at record levels in some places, Nickless said, and will melt eventually.
“This is not the end of the high water, this is just kind of the beginning,” he said, adding that high water and flooding occurrences will continue through May and into June.
Flooding is expected to continue in Missoula, where the Clark Fork River is causing the biggest flood event in Western Montana.
For weather forecast information, visit http://www.wrh.noaa.gov/mso.
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