Cold spring sets new weather lows
According to the National Weather Service, summer arrived Tuesday at 11:16 a.m. in Western Montana, and the new season delivered the warmest weather of the year, triggering mountain snowmelt and flood conditions after a record-setting spring for cold, wet weather.
It was the coldest spring since 1975 across the Northern Rockies.
“Records were set at Missoula, Kalispell and Butte each for the fewest number of days above 70 [degrees] and for the lowest average high temperatures,” a Weather Service advisory states.
In Kalispell there were only nine days above 70 degrees this spring, the lowest number on record since 1899. The average temperature for the season was 47 degrees, the second lowest on record; the 46.9-degree average in 1955 is the record.
And it was a record-setter for Kalispell with the lowest average high daily temperatures from April 1 through June 20. Kalispell’s average of 57.6 degrees surpassed the previous mark of 58.8 set in 1955.
The cold was accompanied by above-average precipitation. Kalispell’s 6.64 inches of spring precipitation was the 11th-highest on record.
The Weather Service attributes the extended cold and abundant snowfall across the entire Northern Rockies to the strongest La Nina weather pattern since the winter of 1988-89.
But with temperatures this week reaching into the 80s and upper 70s, a long-delayed high-elevation snowmelt got under way.
More significantly, overnight temperatures in the 40s and 50s at high elevations will sustain snowpack runoff, said Dan Zumpfle, a meteorologist with the National Weather Service in Missoula.
Zumpfle said that this week, the Flathead River system is the “one we’re most concerned with” regarding flood potential.
The North Fork Flathead River at the Canadian border is expected to rise to what is considered major flood stage of 10.5 feet. It is expected to exceed that level today or Friday and then rapidly decline.
The Middle Fork Flathead River at West Glacier is expected rise close to its 10-foot flood stage by Friday.
And the main stem Flathead River as measured at Columbia Falls is expected to reach its 14-foot flood stage by Friday, with flows of 51,000 cubic feet per second.
As of Wednesday afternoon, the Flathead River was running just over 13 feet.
Zumpfle said there also is concern about rapid runoff overflowing streams on the west slopes of the Mission Mountains and other area mountain ranges.
Reporter Jim Mann may be reached at 758-4407 or by email at jmann@dailyinterlake.com.