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Tuesday, October 16, 2018 at 11:16 AM Issued by: Spencer Logan  


We received quite a healthy does of snowfall in the middle of October. Storm totals ranged from 1 to 2+ feet across much of Colorado's mountains over 11,000 ft. In windy areas along ridgelines, winds have redistributed the new snow into soft slabs over two feet deep. This is more than enough snow to make animal tracking easier for hunters, and provide enough coverage to get eager early season skiers and riders out into avalanche terrain to make turns. With new snow on the ground, if you are going to be out in the mountains, you need to keep avalanche safety at the forefront of your decision making. 

Our first few observations of the season report a thin snowpack with winds strong enough to drift the recent snow in near and above treeline areas. This means you can trigger avalanches in the freshly wind-drifted snow up to a couple feet thick on lee features and in cross-loaded gullies.

* On Friday 10-12-2018, a skier on Loveland Pass triggered and was caught in an avalanche on one of these wind-loaded slopes. The skier was able to get off the slab near the top, but he could have easily gone for a rough ride. Here is a picture of the avalanche from another party.
* On Monday 10-15-2018 a hiker was caught in an avalanche on south Arapaho Peak in the Front Range. The avalanche swept him over cliffs and left him injured. He provided great details for an incident report. 
* We have also received multiple reports of what appear to be natural Wind Slab avalanches running to the ground in popular touring locations around the State.

To help reduce your risk of being caught in one of these avalanches and possibly taking a rough, dangerous ride, you should avoid all areas where you see evidence of previous wind loading. The snow in wind-loaded areas may be harder or may appear smooth. You are most likely to find these dangerous wind-loaded slopes at high elevations, just below ridgelines or below small cornices. Cracking in the surface snow indicates you have found a drift capable of producing a Wind Slab avalanche. You can greatly reduce your risk from avalanches by sticking to lower-angle terrain with no locally connected steeper slopes above.

If you trigger and are caught in an avalanche in the early season snowpack you can easily get injured even if you are not buried. Do not let the excitement of a few turns overwhelm your ability to make good decisions in the backcountry. Make sure you are riding with a partner and that everyone has an avalanche transceiver, probe and shovel. Nearly every fall, avalanches catch eager riders and late-season hikers off-guard. Hunters traveling through the high country need to exercise caution on steep, snow covered terrain. Please be thinking avalanche if you visit steep slopes in the high country. Below we describe some considerations for early-season fall avalanche concerns. 

We will update the Statewide Avalanche Conditions as necessary. On November 1, 2017, we will resume our daily weather forecasts. Our backcountry avalanche forecasts will begin in mid-November.

If you are going into the Colorado high country use our Weather Stations by Zone page to check current conditions.

Avalanche and Snowpack Discussion 

Avalanches are possible in the mountainous areas of Colorado whenever you find snow on a steep slope. In general, you should consider the consequences of being caught in an avalanche before you cross any steep, snow-covered slope, but below are some avalanche problems you may encounter this fall.

Most avalanches happen during or right after a snowstorm. However, any time new snow falls and the wind moves it through the terrain, avalanches are possible. New snow often has a hard time adhering to hard, icy old snow surfaces, so a fall snowstorm can produce small avalanches if it falls onto old snow, grassy areas or rock slabs. The best way to manage these avalanches in the fall is to have a current weather forecast, recognize when there is enough snow to produce avalanches, and select terrain that minimizes your exposure to the risk.We will update the Field Reports as information comes in, so please send us your observations.

Storms Slab avalanches are the release of a soft cohesive layer (a slab) composed of new snow that breaks within the storm snow or on the old snow surface. They often form when new snow falls with light winds or in wind-sheltered areas. They typically last for a few days. You can reduce your risk from Storm Slabs by waiting a day or two after a storm before venturing into steep terrain. Storm slabs are most dangerous on slopes with terrain traps like gullies or cliffs, or slopes that end in timber or scree fields.

With Wind Slab avalanches, wind-drifted snow forms the cohesive layer (a slab). Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Drifted snow is often smooth and rounded, and sometimes sounds hollow. They form in specific areas leeward of terrain features. You can reduce your risk from Wind Slab avalanches by sticking to wind-sheltered or wind-scoured areas and avoiding drifted spots.

Loose Dry avalanches are a release of dry, unconsolidated snow. They start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Loose Dry avalanches are usually relatively harmless to people. They can be dangerous if they catch and carry you into or over terrain traps like gullies or cliffs, or slopes that end in timber or scree fields.


Recent Tweets

@CAIC: You are most likely to encounter dangerous avalanche conditions on the lee side of high-elevation ridges where winds have distributed new snow into soft wind slabs over 2 feet thick. These slabs are large enough to take you for a dangerous ride Oct 15, 11:13 AM
  • A skier triggered this wind slab on Loveland Pass on Friday 10-12-2018. You can trigger avalanches just like this on high elevation wind-loaded slopes just below ridgelines and small cornices. To help reduce your risk of injury avoid all wind-loaded slopes. (full)
  • A hiker was caught in this avalanche near South Arapaho Peak on 10-15. The hiker's tracks are circled in green. The avalanche broke above and to the east (right side of the image. The avalanche carried the hiker along the red line and he stopped at the red X. The majority of the avalanche debris flowed through the gully to the east. (Photo an annotations provided by the hiker) (full)

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Avalanche Observations
Report Date # Elevation Aspect Type Trigger SizeR SizeD
View Mon Oct 15 - TL S SS AF / u R2 D1.5

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Field Reports
Report Date Observer Snowpack Obs Avalanches Media
View Mon Oct 15 Chris Peterson No No Yes (2)

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Weather Observations
Station Date Time Temperature Relative Humidity Wind Speed Wind Direction Max Gust 24 Hr Snow
Bear Lake Thu Oct 18 10:00 AM 31 - - - - 1.0
Steamboat Lake State Park Thu Oct 18 10:00 AM 34 82 1 129 3 0.2
Bottle Peak Thu Oct 18 9:50 AM 34 60 1 303 2 -
Berthoud Pass Thu Oct 18 9:00 AM 28 65 6 284 13 -
Cameron Pass Thu Oct 18 9:00 AM 35 56 5 262 10 0.2
Kendall Mt Thu Oct 18 10:00 AM 19 96 6 136 15 -
Loveland Pass Thu Oct 18 10:00 AM 30 64 8 227 19 -
Molas Pass Thu Oct 18 10:00 AM 30 83 5 226 14 2.9
Putney Thu Oct 18 10:00 AM 25 87 17 175 31 -
Swamp Angel Thu Oct 18 10:00 AM 36 63 3 244 9 -
Wolf Creek Pass Thu Oct 18 10:00 AM 26 99 15 229 31 -
Columbus Basin Thu Oct 18 9:00 AM 30 - - - - 5.0
Lizard Head Pass Thu Oct 18 9:00 AM 34 - - - - 2.0
Medano Pass Thu Oct 18 9:00 AM 39 - - - - -
Mesa Lakes Thu Oct 18 10:00 AM 38 - - - - -
Ripple Creek Thu Oct 18 9:00 AM 32 - 0 84 - 2.0
Slumgullion Thu Oct 18 9:00 AM 30 - - - - 2.0
Schofield Pass Thu Oct 18 10:00 AM 36 - - - - -
Storm Peak Observatory Thu Oct 18 9:35 AM 29 94 6 70 8 -
Taylor Park Thu Oct 18 9:57 AM 38 61 2 97 6 -
Wolf Creek Summit Thu Oct 18 9:00 AM 34 - - - - 2.0
Zirkel Thu Oct 18 9:00 AM 36 - - - - 2.0

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