Dry April hurts snowpack, reinforces drought
Laura Lundquist
(Missoula Current) After a La Nina winter that brought enough snow to keep skiers happy, storms in western Montana didn’t keep pace during April, so snowpack is below normal.
In mountains west of the Continental Divide, snowpack overall is about 90% of the 30-year average or less, which doesn’t bode well for a summer that’s predicted to be warmer and drier than normal.
Snowpack in the upper Clark Fork River basin above Missoula peaked on April 13 at 90% of average and has started to decline. The Blackfoot River sub-basin has slightly less with 86% of average. The Bitterroot River basin is slightly worse with 76% of average snowpack.
The center of the state did slightly better with the upper Yellowstone and Smith-Judith-Musselshell river basins containing normal snowpack amounts. Worst-off is the northern Rocky Mountain Front where snowpack was only about 60% of average at the end of April.
In terms of precipitation, which was above normal across a majority of the state during March, that trend didn’t continue during April. The city of Missoula got less than an inch of rain during April, only about 60% of normal, while the average temperature was almost 2 degrees warmer than normal, according to the National Weather Service. Similarly, basins around Missoula received only about 80% of their average monthly precipitation.
Farther south, the Big Hole and Beaverhead received even less, around 65% of average. But farther north, areas north of Kalispell received an average amount of precipitation for the month. The headwaters of the upper Yellowstone also received higher amounts of precipitation during April.
As a result, most of the state as of May 1 was sitting at around 90% of normal precipitation for the year since Oct. 1 with areas along the Rocky Mountain Front having received about 75%.
The lower-than-average precipitation means western Montana is still experiencing drought conditions, as is northern and far eastern regions of the state, according to the U.S. Drought Monitor. Most of western Montana is in moderate drought. But a region between Missoula and Helena extending south to Wisdom and north along the Continental Divide to St. Mary is in severe drought. Within that, the Blackfoot River basin is still in extreme drought, as it was last summer when the river saw record low flows.
However, a good bout of rain and snow at higher elevations fell across the Divide and along the Front during the system that passed through on Sunday and Monday. A few more storms could at least help keep conditions in Montana from getting worse. Fortunately, the next two weeks have a good chance - between 40% and 50% - of bringing more rain to western Montana, along with normal temperatures, according to the National Oceanic and Atmospheric Administration climate predictions.
But the La Nina weather pattern, which tends to bring cooler, wetter weather to Montana, is over, replaced by a “neutral” pattern, according to NOAA. Temperatures in Montana are expected to rise above normal toward the end of May and remain above normal through July. The chance of rain drops off throughout May and the three-month outlook is predicting below-normal precipitation through July.
Those conditions combined with the below-average snowpack means streamflows will likely drop quickly during the summer, and rivers could run lower than normal in the mid- and late-summer months.
It also sets this summer up to have a high risk of wildfires as vegetation dries out. In fact, wildfire season is already underway, as wildfire started Thursday in Beaverhead County south of the Big Hole River, which is in moderate drought. The fire really took off during Saturday’s heat, burning around 1,200 acres in one day. As of Monday, the fire is estimated to have burned around 1,500 acres.
Contact reporter Laura Lundquist at lundquist@missoulacurrent.com.