Field Report

Northern San Juan - CO

2025/02/16
Lat: 37.837, Lon: -107.887
Backcountry Area: Northern San Juan
Author: Chris Dickson
Organization: Forecaster, CAIC

Report Information

Observation Summary

Its official, this was the biggest storm of the 2024-2025 winter season for the Southern Mountains (thus far). Three day storm totals here range from 24" in the valley's to 36-40" at upper elevations. Despite the large snow load, which came in the form of 2"+ of snow water equivalent, our tired and beat up snowpack tolerated the rapid loading surprisingly well. Observers from Rico to Ophir to Telluride all note shockingly minimal natural avalanche activity, especially above treeline, which is surprising considering the strong winds recorded throughout the storm. Most natural avalanche activity fit into two boxes: medium to large Storm Slab avalanches near and above treeline that released during the first peak of the storm, sometime overnight in the early morning hours of Valentine's Day (with many crowns re-filled in), and small Storm Slab avalanches below treeline on steep slopes (35+ degrees) that failed later in the storm (possibly 2/15, fresher-looking crowns). So far, no avalanches have been observed failing on deeper persistent weak layers, and there have been no human-triggered avalanches reported yet on the Telluride side of the San Juans.

Area Description

West-side of the northern San Juan mountains along Highway 145 and Ophir.

Route Description

Cataloguing natural avalanche activity from the Valentine's Day storm.

Avalanches

Saw an avalanche

I drove along Highway 145 on Sunday morning and observed a minimal amount of natural activity, then I toured in Waterfall Canyon and only found one recent natural Storm Slab avalanche below treeline and several slab avalanche that failed during the storm.

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Date # Elev Asp Type Trig SizeR SizeD Problem Type Location
02/15/2025
2 TL NE SS N R2 D2 Storm Slab
02/14/2025
1 >TL N SS N R2 D2 Storm Slab
02/15/2025
1 >TL NE SS N R1 D1 Storm Slab
02/14/2025
1 <TL SE SS N R1 D1 Storm Slab
02/15/2025
1 <TL NE SS N/y R2 D1.5 Storm Slab
02/14/2025
1 >TL NE SS N R2 D2 Storm Slab
02/15/2025
1 <TL E SS N R1 D1 Storm Slab
02/14/2025
1 >TL SW SS N R2 D2 Storm Slab
02/15/2025
3 >TL SE SS N R1 D1 Storm Slab

Snowpack

Cracking: Minor
Collapsing: Minor

I measured 90cms (~36") of settled storm snow at 11,700' on a northeast-facing slope in Waterfall Canyon. A friend reported 96cm of unsettled snow towards the end of the storm at 11,000' on a similar aspect. Sunday's warm temperatures and strong morning sun quickly transformed the new snow on east aspects, leading to rapid settlement and heavy moist snow on sunny slopes. A suncrust formed on most slopes facing east through south, but it's possible that afternoon clouds kept west-facing slopes slightly cooler. While no slab character was originally observed in the new snow, Sunday's settlement changed that by midday, and at 1:15pm a backcountry rider reported a large whumph on a previously skied east-facing slope. An ECT performed near treeline, where the 90cm of new snow was measured, at 10am did not result in any failures or propagation (ECTX). The total height of snow in that pit was 240cm.

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