March brings record low snowfall to Montana mountains
Following a brutally cold February with record snowfall totals in the Flathead Valley, March finished up like a lamb.
According to USDA Natural Resources Conservation Service snow survey data, all mountain locations in Montana experienced well below normal snowfall for the month.
“Many mountain SNOTEL sites received record-low March monthly precipitation totals, and others were second lowest on record,” said Lucas Zukiewicz, NRCS water supply specialist.
The meager snow totals are most notable in Northwest Montana. Precipitation in March for the Flathead Basin was just 36 percent of average.
Year-to-date snowpack in the Flathead Basin was running 86 percent of average on April 1, while the Kootenai Basin was 84 percent of average. Combined, the Columbia River Basin is 93 percent of normal for this time of year.
“Snowpack in the northern mountain ranges remains below normal for April 1 and below normal March snowfall certainly didn’t help,” Zukiewicz said.
The Flattop Mountain weather station in Glacier Park showed 87 inches of snow on the ground on April 4. That snowpack held a snow water equivalent of just 32 inches - the depth of water that would theoretically result if the entire snowpack were melted instantaneously.
Northwest Montana valley snowfall totals this season, however, remain ahead of average. Kalispell received 6.1 inches of snow in March, ahead of the 5.8-inch average for the month. Season to date, Kalispell has received 66 inches of snow. The avearge total for this time of year is 51.2.
Some river basins were able to keep snowpack totals at near or above average. Snowpack percentages in the mountains supplying river basins in the central part of the state are near normal, while southern basins reporting above normal totals on April 1.
“February was such a big month for snowfall in the central and southern basins that even though they experienced a record dry March, snowpack remains near or above normal for this date,” Zukiewicz said. “It may have saved winter and our spring and summer runoff.”
Zukiewicz said rivers west of the Divide aren’t likely to make up the difference with the peak snowfall season in the rear-view mirror.
River basins west of the Divide are typically frontloaded with snowfall and precipitation from November through March, he said, while basins east of the Divide typically experience their largest monthly precipitation totals from March through June.
“That means that the time for recovery in snowpack totals before runoff begins in these areas is running out as we progress further into spring, especially in northern basins west of the Divide,” Zukiewicz said. “While it’s still not impossible, it is less likely.”
Zukiewicz said March was a solid representation of an El Nino influenced weather pattern.
“February was an anomaly,” he said, noting that a high pressure blocking patter over Gulf of Alaska ushered in all the record cold and snow. When that broke down, it impacted whole state, he said.
April 1 snowpack totals give more clear insight into the snowmelt component of runoff across the state, and streamflow forecasts issued by the NRCS for the April 1 to July 31 period reflect the variation in snowpack and precipitation across the state this year.
Forecasts for river basins in the northern half of the state indicate below average streamflow volumes this spring and summer, while central and southern river basins have forecasts that are near to above average.
Spring mountain snowfall and valley precipitation plays an important role in the runoff for any given year, and this year will be no different.
“Snowpack across the state typically peaks during the month of April, meaning the next month will give us an idea of the total volume of water stored in the mountain snowpack ‘reservoir,’” Zukiewicz said. “That will tell us a lot about what we can expect relative to spring and summer runoff.”
Long-range forecasts issued by the National Weather Service’s Climate Prediction Center indicate increased chances of above average temperatures across the western half of the state for April : June and increased possibility of precipitation across the southern half of the state. “If this winter has taught me anything, it’s to expect the unexpected,” Zukiewicz said. “We’ll wait and see what April delivers.”