Despite late January storms, periods of high-pressure last month resulted in sunny skies and above average temperatures in Montana, causing monthly snowpack percentages to decline in many river basins.
Heavy snowfall across much of the state brought a much needed system of storms adding 1.5 to 3.5 inches of snow to water equivalent to the snowpack, helping some basins in central, south-central and southwest Montana remain or improve to near-to-above normal for Feb. 1. Although the basinwide snowpack percentages in Gallatin and Upper Yellowstone indicate near-to-above normal snowpack conditions, there are some areas in southern Montana that have been largely missed by this winter’s storms, according to the Natural Resources and Conservation Service.
“The late month storms really helped some of the towns in southern Montana where tourism from snowmobiling is critical to the local economies,” Lucas Zukiewicz, NRCS hydrologist for Montana, said in a news release. “The snowpack in both Cooke City and West Yellowstone was the lowest it’s been in quite a few years in mid-January, and news gets out.”
Fortunately, he said, the storms helped these areas recover some by Feb. 1, although snowpack remains below normal. Almost all basins east of the Continental Divide have improved snowpack percentages from Jan. 1, but some regions remain below normal for snowpack.
Snowpack east of the Continental Divide was at 93 percent of normal overall and 95 percent for both the Missouri and Yellowstone river basins. This year is also pacing far behind last year’s well-above average snowfall with only 74 percent.
The western half of the state also benefited from the late January storms, but the river basins experienced decreases in snowpack percentages since Jan. 1 and remain below normal.
“The storms just weren’t enough in the western half of the state to make up for the deficits we’d experienced early in the winter,” Zukiewicz said. “Even with the impressive totals from the late month storms, snowfall ended up being below normal for the month of January.”
Snowpack west of the Continental Divide was at 87 percent of normal and the Columbia River basin was also at 87 percent. Compared to last year, basins in the west were at 72 percent.
River basins in the northwest region of the state typically experience their “wettest” months of the year from early November through the end of January. Below-normal snow totals in these areas for this date make recovery to “normal” snowpack conditions before runoff begins less likely.
“For example, the Flathead River basin would need to receive around 135 percent of normal snowfall between now and when the snowpack reaches peak accumulation, which typically occurs sometime in April,” Zukiewicz said. “While that’s not impossible, it would certainly take a major pattern shift from what we’ve seen so far this winter.”
Similar to last month, mountain temperatures were above average in January, and could be one of the impacts the region is experiencing from the weak El Nino that is occurring this year. Whether it strengthens or weakens into the summer of 2019 is still to be determined, but long-range forecasts continue to indicate above-average temperatures for the February through April time-period.
“That’s something we’ll be keeping an eye on,” Zukiewicz said. “Early runoff doesn’t benefit anyone, so hopefully spring is cooler than anticipated.”
While long-range forecasts call for above-average temperatures, February so far has brought frigid temperatures to Montana and snow in many parts of the state. Forecasters at the National Weather Service in Great Falls expect that trend to continue into next week.
“Another strong cold front with reinforcing blast of Arctic air will move through the area beginning before sunrise Friday morning near the Canadian border and reach the far southern Montana border with Idaho by midday Saturday,” according to forecasters. “Temperatures will plummet back below zero and stay there through the weekend, especially for the north-central and central Montana plains. Temperatures moderate a bit toward early next week, but the extent of the moderating trend is still uncertain at this time.”
Wind chills are expected to plummet past 40 below zero in northcentral Montana through the weekend while the greater Helena area could see wind chills in the minus 30 range.
The weather service also expects snow and the possibility of blowing snow to accompany the front. The heaviest snowfall of up to 6 inches is forecast in northcentral Montana while the greater Helena area is forecast for 2-3 inches through Sunday.