19-20
GNFAC Avalanche Forecast for Mon Nov 18, 2019
Snowpack and Avalanche Discussion
<p>Winter handed the reigns back to fall. In one week’s time we went from temperatures below zero to rain. Since Thursday's bulletin the northern Gallatin and Big Sky area picked up 3-5" of dense snow on Friday and .3” of rain last night while cold temperatures in the south allowed it to snow 1-3”. Rain followed by temperatures below freezing is good for the stability, but not so good for skiing. Slopes above 9,000’ got snow, so if you are willing to trudge through low and mid-elevation glop, you’ll be rewarded.</p>
<p>In general, snow stability is good. In the mountains there is 2-2.5 feet of snow and our pits and public observations point to a relatively stable snowpack of crusts and strengthening snow. On Saturday, skiers on Mt Blackmore (<u><strong><a href="https://www.mtavalanche.com/images/19/digging-pit-mt-blackmore">photo</…;) and Hyalite Peak (<u><strong><a href="https://www.mtavalanche.com/images/19/wind-effect-hyalite">photo</a></s…;) found no instability.<br />
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Looking ahead to Tuesday and Wednesday’s storm, stability concerns will be confined to new and windblown snow throughout our advisory area. The storm will start warm and then cool which should help it adhere to the old snow surface. Wind with the storm will create drifts so be attune for shooting cracks, a sign of instability. Our limited field data shows slopes to be generally stable, but we need more information. If you'd like to help us you can quickly fill out an <u><strong><a href="https://www.mtavalanche.com/node/add/snow_observation">observation form</a></strong></u> and attach a picture or two. You can also email us (<u><strong><a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a></strong></u>), leave a message on our phone (406-587-6984) or Instagram (#gnfacobs).</p>
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out and plan to attend one or two: Events and Education Calendar.
BOZEMAN
20 November, 1-hr Avalanche Awareness, 7-8pm @ The Mountain Project.
Weather and Avalanche Log for Mon Nov 18, 2019
Rain to ~9,000 feet in northern ranges.
A skier on Saturday (11/16) took the time to dig a quick pit about 200' below east ridge of Mt Blackmore. He found about 2.5 feet of snow with a few crust layers. Photo: K. Stewart
Forecast link: GNFAC Avalanche Forecast for Mon Nov 18, 2019
Rivers of loose snow avalanches in Flanders Drainage
Flanders Creek
Northern Gallatin
Code
L-N-I
Elevation
9500
Aspect
E
Latitude
45.44020
Longitude
-110.93100
Notes
From Doug Chabot:
I went ice climbing in Flanders and got hit with a graupel storm (0830) which avalanched off the climbs on east-facing slopes for over an hour. It was pretty spectacular and we found knee deep graupel (small, ball-bearing like grains) 200 vertical feet from the bottom of the cliffs. The climbs that we saw this on were Big Sleep, Bobo Like and Killer Pillar. The snow appears to be sliding on a razor thin ice crust under the 3" of new snow that fell last night, which was dense (estimated 15%).
I dug a hand pit to the ground and found 2' of mostly solid snow (no obvious facets) with a couple ice crusts in the upper third. A CT cut with a ski pole yielded no fractures. Elevation 8,000', east aspect.
Number caught
0
Number buried
0
Avalanche Type
Loose-snow avalanche
Trigger
Natural trigger
Bed Surface
I - Interface between new and old snow
Problem Type
Loose Dry
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Multiple Avalanches
Advisory Year
From obs: "Went for a tour up to Hyalite Basin. No recent sightings of avalanche activity in the basin. There was substantial wind effect on East aspects at 9,000 feet including a dense 3 inch wind layer that was present up to the saddle, which did not propagate in our ECT. We observed a crust layer on south aspects at 7,000 which likely formed before the most recent snow." Photo: Tommy Saulnier
Forecast link: GNFAC Avalanche Forecast for Mon Nov 18, 2019