MISSOULA — Southwest Montana has the biggest risk of a serious wildfire season this summer, while much of the rest of the state could see more normal conditions.
“It’s probably a good year for the Sapphire (Mountains) to burn again,” Brian Henry of the Northern Rockies Predictive Service told a conference of water experts in Missoula on Tuesday. “And the Flint Range and the Pintlars.”
Beaverhead, Madison, Deer Lodge and parts of Ravalli counties still suffer from last year’s drought conditions that persisted into mid-fall. And this year, those counties are forecast to get 40 days of thunderstorms, while the rest of the state could see 30 or fewer. Most of Montana’s serious forest fires are lightning-caused.
Parts of Idaho south of the Salmon River corridor west of Lost Trail Pass also look primed for a heavy fire season, Henry said. That’s the same area where the massive Mustang and Halstead fires pumped smoke into the Missoula Valley last August and September.
The rest of the state has benefited from late-spring rains to build moisture and reservoir conditions close to average, despite earlier analyses indicating a dry year. That’s particularly true for south-central and southeast Montana, where calls for an early and intense fire season have been scaled back.
The next week should see continued heavy rain across much of the state. But after the first week of June, National Weather Service outlooks call for summer conditions to take hold.
That could lead to earlier-than-usual river dropoffs, especially in the Upper Clark Fork and Bitterroot drainages of Western Montana, according to Brian Domonkos of the Natural Resource Conservation Service office in Bozeman.
“We may be seeing low rivers sooner than average this summer,” Domonkos said. “Flint Creek is running about 30 percent of average – that’s the lowest in the region. But most of the others are running 60 to 70 percent of average. So we could see stressed streamflows come July or maybe as early as June.”
Snowpack in the Bitterroot Valley and Upper Clark Fork River drainage each hit about 80 percent of average this winter, thanks to a late surge of snow and rain in May. The Flathead River system and others in northwestern Montana all came in closer to 100 percent, Domonkos said.
Bitterroot Irrigation District member Harvey Hackett said he was seeing that play out already on the east side of the valley. Soil moisture levels in the area were still depleted from last fall, he said.
“When we don’t pick up water out of the east side, we’re in trouble, and we’re in trouble right now,” Hackett said. “We’re drawing water from the lake (Como Reservoir) and we shouldn't be doing that before July 1.”
In the larger weather picture, conditions look on course for a summer midway between the wet-and-cool La Nina pattern and the hot-and-dry El Nino. Mountain snowpacks have melted earlier than average, which often coincides with a much-larger-than-average fire year for acreage, Henry said.
On the good news side, this summer looks like it will bring season-ending events in September. Last year, many fires burned into October because fall rains came so late.