Missoula, Montana: From Snowstorm to Avalanche to Flood Threat In 1 Week

By: By Jon Erdman

Published: March 6,2014

 

 

 

   This week, on the heels of another swipe of snow for the snow-weary, we've seen record-smashing cold in parts of the Midwest, South and East.
(MORE: Snowiest Cities | March Cold Records | Great Lakes Ice Nearing a Record)
With apologies to those of you who are sick of winter, I would submit Missoula, Mont. has had it toughest over the past week or so.
Let's recap what they've gone through:
That's more snow in one month than their annual average of 39.9 inches! The 30-year average February snowfall, typically only the third snowiest month in Missoula, is 6.5 inches. According to the National Weather Service forecast office in Missoula, 26 of 28 February days featured at least a trace of snow.
This was punctuated by a snowstorm at the end of February into March during which 11.9 inches of snow fell.
Not only was travel snarled, but the combination of high winds and heavy snow created an unstable snow slab on Mt. Jumbo northeast of downtown Missoula, eventually releasing a deadly avalanche on Feb. 28 in Rattlesnake Valley.
(MORE: Avalanche Buries Montana Home)
According to an article in The Missoulian, the avalanche released an estimated 80 percent of the snow in the Mt. Jumbo basin. It was the first slide on the west face of the mountain in at least 50 years.
Then, on Tuesday, a plane slid off a runway into a snowbank at the Missoula International Airport while taxing. No injuries were reported among the 44 passengers and three crew members.
Now, it's rain and warmer temperatures that are a concern.

Flood Threat

Current Conditions

• Missoula, MT

  
  44^°F
  Cloudy

While the Arctic air has retreated, the Pacific storm track remains pointed at the Northwest and northern Rockies, as it typically is in late winter.
For most valley locations, this means a break from the snow. However, this isn't the rosey picture it may sound like. There are three main impacts from this warmer pattern change:

• Flooding in low-lying areas, as rain, coupled with warmer temperatures, melt the existing snowpack.
• High avalanche threat due to heavy wet snow, even rain, loading on existing snowpack in the mountains.
• Refreezing of meltwater overnight will lead to icy stretches on roads, driveways, and sidewalks during the morning.

Missoula firefighters already were digging trenches Tuesday to divert meltwater away from area homes, according to another story in The Missoulian.
Tuesday, a stretch of Interstate 90 northwest of Missoula to the Idaho border (Lookout Pass) was shut down due to avalanche danger.
Here is the general timing of the precipitation in the Northwest and northern Rockies:

• System #1: Through early Friday
• System #2: Late Saturday through Monday

(MORE: NW Flood Alerts | Rain/Snow Forecast)
Montana isn't the only place facing this threat. Flood alerts are also posted in parts of Washington, Oregon and Idaho, as snow levels will only begin to fall off on Thursday behind a weak cold front. Expect rapid rises on small creeks and streams in the Northwest during periods of rain through the weekend.
The avalanche danger will remain high in parts of the Washington and Oregon Cascades. Avoid backcountry and out-of-bounds areas until the danger subsides.

MORE: Wilderness Career: Avalanche Forecaster

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An avalanche dog, followed by rescuers, looks for a person buried in the snow, on December 11, 2012, during an avalanche dogs training session near Les Deux Alpes ski resort in the French Alps. (JEAN-PIERRE CLATOT/AFP/Getty Images)