Flooding could start this week

The National Weather Service expects mountain snowpack to begin melting at a more rapid rate beginning Wednesday and extending through Friday, according to a weather outlook released Saturday afternoon.

A ridge of high pressure is forecast to bring warmer air to the Northern Rockies, increasing the likelihood that small streams and creeks will spill out of their banks by Friday.

The warmer weather system is expected to come on the heels of persistent rain and snowfall today and Monday at elevations above 6,000 feet, where snow levels are already well above historic averages.

Beginning Wednesday, “the considerable snow pack that currently exists in the mountains will begin to melt at an increased rate. Significant rises in small streams and creek levels are possible by mid-week with some small streams exceeding their banks  by week’s end,” according to the Weather Service statement.

Main stem rivers are also expected to rise by the end of the week, though none are forecast to reach flood stage by then.

The Weather Service outlook includes waterways in the Flathead and Mission valleys as well the West Glacier region and much of northwest and west-central Montana and north-central Idaho.

The Weather Service has been projecting that rivers and streams across the region will reach or exceed flood stage in the latter part of May and continue into June, though it could happen earlier if there is an extended warm period.

The National Weather Service Forecast Office posts hydrographs of predicted river levels on its website at www.wrh.noaa.gov/mso/hydrology/composites.php.