20-21

<p>In the mountains around Bozeman and Big Sky westerly wind tapered off last night after raking the mountains with 45-100 mph gusts since Sunday. It snowed 3 to 4 feet last week and the strong wind added many more feet. <a href="https://youtu.be/65JO-4w4qXo"><strong><u>Dave’s video</u></strong></a> standing under a 10-foot crown in MacAtee Basin on Buck Ridge illustrates the power of wind-loading. The snowpack quivered under these loads and on a few slopes it broke deep on sugary facets (depth hoar) near the ground. Alex investigated a deep slab avalanche on Mt. Blackmore last week (<a href="https://youtu.be/Ychm42ihtjk"><strong><u>video</u></strong></a&gt;) and another slide broke deep on Saturday on its north face (<a href="https://www.mtavalanche.com/images/21/crown-north-blackmore"><strong><u…;). Other deep slabs on Alex Lowe Peak and Flanders Mtn, plus a couple outside Big Sky Ski Resort (<a href="https://www.mtavalanche.com/images/21/lone-lake-cirque-avalanche"><stro… Lake Cirque</u></strong></a>) leaves no doubt about the avalanche potential.&nbsp;</p>

<p>The previous three days of wind-loading remains a problem. I recommend staying off wind drifted slopes since triggering them is likely. Chalky, hard, and textured, avalanches involving these drifts are bad enough, but they could trigger a deeper slide. The avalanche evidence is all around us. For today the avalanche danger is rated CONSIDERABLE on all wind-loaded slopes and MODERATE on all others.</p>

<p>The avalanche concern in Cooke City are wind-loaded slopes from strong W-NW wind. Yesterday, Ian saw 2 wind slab avalanches on Mt Henderson from the Lulu road and 2 other skiers reported a small slide on Sheep Mountain and another on the east slopes of Republic Mountain (<a href="https://www.mtavalanche.com/node/24401"><strong><u>activity report</u></strong></a>). Although these avalanches were small, they indicate larger ones are not out of the question. Give wind-loaded slopes a wide berth since you are likely to trigger a slide. Thin snowpacks and/or rocky terrain are a secondary problem because these slopes harbor weak, faceted snow near the ground which can be triggered. Luckily they are found only in isolated areas, that is until you find one, then it’s unlucky. For today, the avalanche danger is rated CONSIDERABLE on all wind-loaded slopes and MODERATE on all others.</p>

<p>The mountains south of Big Sky to West Yellowstone have 2 competing issues: wind drifting and weak, faceted snow near the ground. Dave and I rode in Lionhead yesterday hunting for avalanches. The wind-loading was impressive with entire bowls of textured and drifted snow. Triggering a slide on a wind loaded slope may start small, but the initial avalanche could break deeper on facets. I made a <a href="https://youtu.be/C1F9DWC-gfA"><strong><u>video</u></strong></a&gt; explaining these 2 concerns while standing near the debris of a slide from a few days ago (<a href="https://www.mtavalanche.com/images/21/natural-avalanche-behind-lionhead…;), and found more evidence of lurking instability from a recent cornice triggered avalanche (<a href="https://www.mtavalanche.com/images/21/natural-avalanche-lionhead"><stro…;). The southern mountains got a full serving of wind and triggering slides on these wind drifted slopes is possible which points to a MODERATE danger. Avoiding wind-loaded terrain is a good strategy for today.</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong><u>websi…;, email (<a href="mailto:mtavalanche@gmail.com"><strong><u>mtavalanche@gmail.com</u></str…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>