Advisory for Fri Nov 24, 2017

Good Morning and happy Black Friday. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Friday, November 24th at 7:00 a.m. Today’s advisory is sponsored by Yellowstone Club Community Foundation and Montana State Parks. This advisory does not apply to operating ski areas. Due to the prolonged period of warm temperatures, Bridger Bowl will not be opening this weekend.

Mountain Weather

Overnight a fast moving cold front dropped 2-3” of high density snow in the mountains around Bozeman and Big Sky. The snow line ranged between 8-9,000 ft. and rain fell at lower elevations. The mountains around West Yellowstone and Cooke City picked up a trace to 1” of snow above 9,000 ft. At 5 a.m. snow and rain showers have tapered off and temperatures range from the upper 20’s to mid-30’s F. Winds are blowing 20-40 mph out of the west with ridgetop gusts pushing 50 mph. The Cooke City weather station near Lulu Pass recorded a gust of 79 mph this morning. Today, both precipitation and high winds will diminish as a weak ridge of high pressure builds over the region. Temperatures will warm into the mid to upper 30’s F under partly cloudy skies and winds will blow 15-30 mph out of the west. No snow is expected over the next 24 hours and the rest of the weekend looks to be mostly dry.

Snowpack and Avalanche Discussion

All Regions

If you didn’t get enough mashed potatoes at dinner last night, there should be plenty in the mountains today. The combination of above freezing temperatures and rain at mid to low elevations will turn the snow into a soft and sticky mess. Above 8,500 ft. temperatures have dropped below freezing, which will firm up the snow surface at least during the morning hours.

Today, there will be a variety of avalanche problems to look out for. Below 8,500 ft. the main problem will be wet loose avalanches. The lack of freezing temperatures combined with rain has turned the snowpack nearly isothermal in many locations. This means the snowpack has lost much of its cohesion and strength, which will make wet snow avalanches possible in steep terrain (photo). Be extra cautious when traveling in areas where terrain traps such as creek beds or gullies are present.

A secondary avalanche problem will be wind slabs. This hazard will be confined to upper elevation terrain loaded by westerly winds. I don’t expect fresh wind slabs be exceptionally large or touchy, but they will be something to look out for when traveling at higher elevations.

In non-wind loaded areas where temps have dropped below freezing the snowpack will be mostly stable. Earlier in the week, Doug and I rode and skied around Cooke City and found mostly stable snow in our snowpits. Even on sunnier aspects, which usually hold shallower and weaker snow, the structure was strong and stable (video, photo).

Today, the wet snow avalanche danger is rated MODERATE on mid to low elevation slopes. The dry snow avalanche danger is rated MODERATE on high elevation, wind loaded slopes.

If you get out and have any avalanche or snowpack observations to share, drop a line via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).

Some days the big lines will go, but other days they won't. It's up to you to decide, because the best days are the ones when you return home safely. Three skiers walk through the decision making process in Get Avalanche Smart - Episode 3: The Great One.

Upcoming Avalanche Education and Events

Events and Education Calendar

BOZEMAN

Nov. 28, Avalanche Awareness, 6-7:30 p.m. at Play it Again Sports

Nov. 29, 30 and Dec. 2, 3 or 9, Introduction to Avalanches w/ Field Day, Info and Register Here

Dec. 6, Avalanche Awareness, 6-7:30 p.m. at REI Bozeman

Dec. 7, Avalanche Awareness and Beacon Practice, 6-8 p.m. at Beall Park, Bozeman

Dec. 13, Avalanche Awareness, 6:30-8 p.m. at Gallatin Valley Snowmobile Association, 4-Corners

Jan. 12 and 13, Companion Rescue Clinic, Info and Register

Jan. 17, 18 and 20 or 21, Introduction to Avalanches w/ Field Day, Info and Register Here

Jan. 24, 25 and 27, Advanced Avalanche Workshop w. Field Day, Info and Register Here

Feb. 9 and 10, Companion Rescue Clinic, Info and Register

HELENA

7 December, Avalanche Awareness, 6-7:30 p.m. at Basecamp, Helena

WEST YELLOWSTONE

Dec. 14 and 15, Snowmobiler Introduction to Avalanches with Field Course, Info and Register Here

COOKE CITY

24 and 25 November, Current Conditions and Avalanche Rescue, 6:30-7:30 p.m. Friday and anytime between 10-2 on Saturday.


Forecasters’ Choice:

Here’s a new video series from BCA outlining how to use an avalanche transceiver to perform an effective rescue.


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