Montana’s winter is shaping up to be among the worst for snowpack in 25 years and, combined with the current outlook, forecasters warn that streamflow levels this summer could be well below normal across most of the state.
Early last month, Montana forecasters and water supply experts said the state would need above average snow in March and early April, and a wet, cool spring, to prevent the meager remaining snow from melting too quickly and causing low flows in rivers and streams during the growing season and possible drought.
But according to the state and federal government reports And presentations released in the last two weeks, recovery The snowpack formed in February and early March eased over the ensuing weeks and did not continue as much as forecasters had hoped.
“A complete recovery to normal snowpack conditions is unlikely to occur by May 1 of this year in most of Montana,” Montana Snow Survey staff wrote in the newspaper. Water supply forecast for April released by the Natural Resources Conservation Service earlier this month.
“Below normal snowpack conditions on May 1 could be supplemented by above normal spring and summer precipitation, assuming snowpack deficits are not too large. The best-case scenario would be a return to cooler weather and above-normal precipitation for the next few months. »
Since 1991, the median day that Montana’s snowpack as a whole has reached its peak has been April 14, at 18 inches of snow water equivalent, the amount of water contained in the snowpack. So far this year, statewide snowpack peaked at 13.2 inches of snow water equivalent on April 11, three days earlier than normal and nearly 5 inches of snow water equivalent below normal.
THE current snow cover of 12 inches of snow water equivalent statewide is only 74% of normal for this time of year, but also in the 7th percentile compared to 1991-2020. Earlier this month, one in seven snow monitoring stations in Montana had their lowest or second lowest snowpack on record. More than a third of them reported snowpack in the 10th percentile or lower compared to the 1991-2020 period.
It is still possible that storms and cooler weather over the next few weeks will support the snowpack at higher elevations and inhibit snowmelt, but this is generally the time of year when the snowpack begins this which most people hope will be a gradual decline.
Last year, the snowpack peaked at 18.1 inches of snow water equivalent on April 25, but a fast melting occurred due to unseasonably warm temperatures. Two weeks later, the snowpack reached 12.5 inches of snow water equivalent and was completely gone by June 21. The median snow-free date is June 28.
Starting Monday, the snow cover had disappeared into Bear Paw Basin. He sat at 45% of the median in the upper Missouri basin and between 50% and 69% of normal in the Sun-Teton-Marias, Upper Clark Fork, Bitterroot,…
