Precipitation began as rain showers around midday Saturday at the lower elevations. Rain and drizzle flipped to snow, some heavy at times, as chilled air swept in from the north. An approaching weather disturbance helped intensify the storm even more, increasing snowfall rates Sunday morning. In combination with strong winds, it brought near whiteout conditions to parts of the region.
The 48-inch jackpot total came from Browning, a town of about 1,000 in Glacier County, which is about two hours northwest of Great Falls on the Blackfeet Indian Reservation.
“All roads in and out are blocked or pretty bad,” said Remington Boushie, a dispatcher with the Browning Police Department.
These conditions were expected, as the Pondera County Disaster and Emergency Services office issued a message Sunday morning requesting that roadways be used only by emergency vehicles “until further notice.”
“I had to hike about a half mile in it and get picked up by another officer,” Boushie said. “Some officers made it out, but we have two officers stuck in their units. Lots of people are working extra. We’re making do with what we can.”
Boushie noted that the four-foot total exceeded the highest-end forecasts. “We were expecting 15 to 36 inches of snow. So even if we had prepared for the worst, we still got it worse than that.” Boushie added that the snow was light and powdery, making it a bit easier to move in.
What makes this storm unusual is that the bull's eye of heavy snowfall occurred well east of the mountains, in the flatlands leading up to the foothills.
“What happens with the storm system we had was that we had east to northeast low-level flow,” said Ray Greely, a meteorologist at the National Weather Service in Great Falls. “You have what we call the upslope, which with the dynamics, provides additional uplift.” As moisture-rich air is forced upward toward the higher elevations east of the mountains, it cools and rids itself of moisture, falling into chilly air near the ground.
In these cases, “somebody can get a real dumping,” Greely said.
Meanwhile, in Great Falls, initial forecasts called for roughly a foot of snow. The city wound up with 19.3 inches, along with visibility dropping to a quarter-mile Saturday evening as the heaviest bands moved in. The entire episode lasted about 36 hours there.
Of the total, 9.7 inches fell Saturday and 9.6 inches came Sunday. It marked the highest and second-greatest single-day snowfall totals recorded in Great Falls for the month of September. These totals were also the 15th- and 16th-highest daily snowfalls in any month. Records at Great Falls International Airport date back to 1937.
Perhaps most impressive is that this storm marks Great Falls’ second-highest two-day snow total on record, behind only the 24.2 inches that fell on April 28-29, 2009.
“Early” or “late” season snow is not uncommon for the region. Of the 10 biggest two-day totals in Great Falls, only one occurred during meteorological winter (December-February). In other words, nine of the top 10 heaviest winter storms weren’t truly in winter.
“Typically, we do [get our snowstorms on the fringe seasons], since that’s when the moisture is really available,” Greely said. “You can get some storm systems in the winter, but you just don’t have the moisture. That’s why we get our biggest snowstorms in the spring.”
Greely said this latest system would be impressive for any time of year, but he called it “unheard of” for September or October.
“In the fall, you can occasionally get [a snowstorm], but it’s a little more difficult.” And the amounts, he said, are usually nothing like this.
Meanwhile, rain on the storm’s warmer side helped clinch top spots for the wettest September on record for parts of eastern Montana. Glendive saw 8.32 inches this month, beating its former record by more than 2 ½ inches. Sidney saw just under 11 inches this month, with Glasgow also having its wettest September on record.
Now, the concern turns to falling temperatures, which will likely reach record lows in some spots. Great Falls is forecast to drop to 14 degrees Monday night, obliterating the record low of 22 set in 1959. If realized, that low temperature would also be the second-coldest reading on record for so early in the season.
“We’ll be seeing teens and, if it clears out, maybe even a little lower than that,” said Greely, referencing the potential for additional cooling if the blanket of cloud cover exits, allowing any meager warmth to escape into the atmosphere.
In the meantime, temperatures will remain near or below freezing over the next three days, warming into the upper 40s on Thursday. By Friday, the forecast calls for more showers of snow.