Mountain snowpack continued to pile up over the weekend in Northwest Montana, the result of a storm system that arrived Friday.

Automated snow measuring sites across the region recorded snow water equivalents accelerating well above historic averages, largely because snow depths have been increasing at a time when they are normally decreasing.

The Bisson site in the Mission mountains was at 433 percent of average last week, but it was at 656 percent of average by Monday.

The Emery Creek site above Hungry Horse Reservoir was at 240 percent of average but is now at 320 percent of average.

The Many Glacier site was at 300 percent of average but has increased to 396 percent of average.

The Grave Creek site south of Eureka was at 300 percent of average but now measures 389 percent of average.

Snow depths have been increasing, too. At Noisy Basin on the Swan Crest, the snow depth is 188 inches. On Flattop Mountain there is 166 inches of snow.

The National Weather Service has been forecasting rivers and streams across the region to reach or exceed flood stage once the peak runoff gets under way.

The Weather has Service been projecting that will happen in the latter part of May and continue into June, but officials have cautioned that it could happen sooner if there is an extended warm period.

According to the short-term forecast, only a couple of rivers in Northwest Montana are projected to rise substantially. By early next week, the Yaak River is expected to be within a foot of action stage and the Fisher River is expected to approach its flood stage.