Experts forecast flooding by area rivers and streams

With continued cold weather, the potential for flooding by area rivers and streams has increased, the National Weather Service warned last week.

Hydrologist Ray Nickless said at least some flooding is expected by the Flathead’s three forks as well as small streams in Glacier National Park.

The problem is that the snowpack, which is usually shrinking this time of year, is well above average and continues to grow in higher elevations as cold weather and snow persists in the mountains.

The snowpack at Noisy Basin, for example,  is at 167 percent of average for this time of year, and the equivalent of 73.5 inches of water is stored in the snow — what’s called snowwater equivalent. With a snowpack lingering so late into the spring, Nickless said, flooding is almost assured.

The North Fork of the Flathead is expected to reach flood stage, cresting at 12 to 12.5 feet. That’s well below the 16.9 feet the river crested at in 1995, but Nickless said a good rainstorm could send streams gushing even higher. Predicting rain into the future is difficult. Generally forecasters can only predict large rain events a few days in advance.

The Middle Fork of the Flathead is expected to reach 10.1 to 11.3 feet, which is above flood stage, and the mainstem of the Flathead is expected to reach between 14 and 16 feet, which is also above flood stage. The flood of 1964 was well above that — cresting at 25.58 feet.

Nickless said he also expects McDonald Creek and other small streams in Glacier Park to flood as well.

Flooding is expected across western Montana, not just in the Flathead. The Fisher and Thompson rivers should flood, and the Clark’s Fork and Bitterroot rivers will likely reach or exceed flood stage.

When spring runoff begins, the water should stay high for extended periods of time, Nickless said.

The weather isn’t expected to warm significantly, either. The long range forecast for May and June is cool and wet, meteorologist Leeann Allegretto said.

“We’re stuck, people,” she said during a conference call on April 28.