Posted:
Mar 7, 2014 @ 6:35 am

Avalanche Advisory March 7, 2014

The avalanche danger is CONSIDERABLE in the West Central Montana backcountry on slopes 30 degrees and steeper. We have rescinded the avalanche warning from yesterday; but there is still potential to trigger a slide on steep slopes.

Good Morning, this is Dudley Improta with the West Central Montana avalanche advisory for March 7, 2014. This danger rating does not apply to operating ski areas and expires at midnight tonight (March 7).

Weather and Snowpack Analysis

 Westerly winds are blowing  in the 20mph range and gusting in the 30’s at higher elevations this morning. Mountain temperatures are in the high 20’s to low 30’s (F). The area picked up 2 to 4 inches of snow ovenight.

The snow in the Rattlesnakes is still a bit fickle. On Monday we found unstable snow on southeast slopes; we went 700 feet higher yesterday; the snow was gaining strength but propagating in tests on north slopes (video). The south slopes, at a higher elevation, seemed more stable(Rattlesnakes pit profile). I would check for instability before recreating on any aspect in the Rattlesnakes.

Tim and Dave traveled near Lolo Pass and reported a wet and unsupported snowpack up to 6000’ (Lolo Pass pit profile). They felt any cold temperatures would help solidify the snow. Travel will be difficult and it may be possible to trigger a deep wet slide until we see the cool temperatures.

A report from Downing Mountain lodge reported a heavy load from the week’s storms as well. Their main concern is  the continued wind-loading on north and northeast slopes.

Geoff Fast and Ed Snook had unstable results with pit tests about 65 cm into the snowpack (Lost Trail pit profile); much the same problem we saw in the Rattlesnake. This layer could be easily triggered at elevations above 6500 feet.

So, we have a few different chances to trigger an avalanche; relatively heavy snow from the week’s storms sitting on colder snow at higher elevations and weaknesses associated with rain and wet snow below 6500 feet (glide avalanche snowbowl road 3/6/14) .  Don’t be lulled into complacency by a little sun; pay close attention if you are considering riding or skiing any aspect over 30 degrees in steepness.

Weather Forecast and Avalanche Outlook

Snow and snow levels are expected to decrease this morning. High pressure should develop over the region tonight and last through Sunday. Daytime temperatures may warm lower and mid-elevations; particularly on south-facing slopes. I would expect snow stability to improve ever so slightly. Over the weekend, I would definitely check for instabilities with observations and snow pits before committing to any slopes over 30 degrees.

Cheers for Charity – Draught Works – 915 Toole Avenue in Missoula – March 18 – 5pm

Missoulaavalanche is being sponsored at Draught Works on March 18 with “Cheers for Charity”. Come on down and have a pint. The event will help raise a few bucks for the West Central Montana Avalanche Center.

If you would like to send us snow observations; you can use our public observations form on the internet or send us a quick e-mail at  [email protected] .

Ski and ride safe; have a great weekend!

I will issue the next advisory on Tuesday, March 11, 2014.

 

READ FULL ADVISORY  

This information is the sole responsibility of the Forest Service and does not apply to operating ski areas. The avalanche danger rating expires at midnight tonight but the information can help you make a more informed decision regarding travel in avalanche terrain for the next few days.

Our advisory area includes National Forest System lands in the Bitterroot Mountains from Lost Trail Pass north to Granite Pass, the Rattlesnake Mountains north of Missoula and the Southern Swan and Mission Mountains near Seeley Lake, MT. Avalanche information for the Lookout Pass/St. Regis Basin area is available from the Idaho Panhandle Avalanche Center.