Snowpack poised for hefty spring runoff in Western Montana

Snowpack poised for hefty spring runoff in Western Montana

Source: Montana Standard
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ROB CHANEY rchaney@missoulian.com

MISSOULA — Finance managers always warn that past performance doesn’t predict future returns, but they haven’t looked in Montana’s water bank.

“We are way above normal, or average, or median, or whatever statistic you want to look at,” National Weather Service hydrologist Ray Nickless said during a review of the winter water collection as spring runoff begins across western Montana. “We should be having good flows in rivers, filling up reservoirs and plenty of water to go around.”

Since the meteorological “water year” began in October, the Missoula Valley has collected 174 percent of its average snowpack, with 63.7 inches recorded. The average is 39 inches. Kalispell logged 89.8 inches, or 161 percent of average.

Melt that down to water, and both valleys received about 185 percent of average for the cold six months of the year. Some of that came as fall rain in October, and some has appeared as unseasonably early rain in March. The latter has stimulated current high water levels in local rivers, ahead of the more typical spring runoff in May and June. The Clark Fork River near Missoula now flows at about double its usual flow for early April.

Much of the low-elevation snow has melted away in north Idaho and western Montana, but the high mountain snowpack still hangs on. Nickless said that helps reduce the chance of serious flooding later this spring, as the stored moisture gets released in stages. Minor flooding has been predicted for the Flathead and Yaak rivers this month, and some Bitterroot Valley homes have incurred high-water damage. Barring a sudden, warm-rain weather system turning the runoff into a catastrophic surge, the spring should see steady but high flows.

“We’re pretty excited for the health of the river,” said Montana River Guides owner Mike Johnston, who leads whitewater raft and kayak trips on the Clark Fork and Blackfoot rivers near Missoula. “But we’ve learned from experience not to count on it. Some years have great snowpack, but you get a warm early spring and things disappear pretty fast.”

The longer outlook has a faint smiley face. While the April continental forecast calls for above-average temperatures in most of the eastern United States, western Montana and northern Idaho look to be right on the bubble for normal spring temperatures.

Looking further out, the May-June-July outlook has almost all of the nation in above-normal temperatures – except Montana, North and South Dakota and part of Wyoming. That little bullseye also is predicted to get somewhat above-normal precipitation.

“Pretty much the entire country is looking at above average temperatures (for July, August and September),” Nickless said. “That seems like a broken record for what we say every summer now.”