A winter storm warning is in effect until 6am Thursday morning, March 19th. The likelihood of natural and human triggered slab avalanches is increasing. As of 4pm Snowslide Snotel (9730') reports 8" of new snow with 1.2" of snow water equivalent. ASBTP station is not reporting, but Little Spruce station (9379') reports moderate to strong southwesterly winds. More snow and wind will continue through tomorrow.
To help prevent the spread of COVID-19, Arizona Snowbowl has suspended all operations until further notice. Snowbowl road is currently closed, and backcountry access points will require a very long hike, e.g. Lockett Meadow road. Be prepared and pay attention to your energy levels, and your partner's energy levels. With the ski area closed, rescue response will be slow. Make conservative decisions and keep your risk tolerance low, for yourself and the community - now is not a good time to visit a hospital which may be overwhelmed due to COVID-19.
Recent pits reveal that the avalanche triggered by ski patrol may have involved an isolated snowpack structure, but KPAC encourages backcountry users to analyze the March 11th rain-crust (and above snow) on near-treeline slopes - especially northerly slopes just below ridgelines.
Click Read More for a few things to be aware of during this storm cycle.
- 90% of human triggered avalanches happen during or within 24 hours of snowfall. Waiting 24 hours before traveling on or under steep (>30°) slopes will decrease your likelihood of triggering an avalanche
- Venture into this new snow with an "assessment" mindset by selecting conservative terrain in which to gather information
- Check the bonding and reactivity of new storm and wind slabs
- Look for signs of recent avalanches
- Watch for instabilities like cracks shooting out from your skis or board as you skin or ride in fresh snow
- Listen for collapses (whomping) underfoot
- Post storm sunny/warm weather may destabilize new slabs (spring equinox is March 19th)
- Make good decisions upon your observations
- The extended forecast suggest even more unsettled weather next week - keep your guard elevated.
Near and Above Treeline:On March 14, Saturday morning, using explosives in a closed area, Az Snowbowl Ski Patrol triggered an avalanche. NW slope near 11,800ft. The crown was 2-4' deep. It ran approximately 800' and was about 75' wide. The debris pile was ~4' deep where it stopped above the spur catwalk. This was a wind slab that failed on needles resting on the March 11 rain crust. Recent pits reveal that this may have been an isolated snowpack structure, but KPAC encourages backcountry users to analyze the March 11th rain-crust (and above layers) on near-treeline slopes - especially where you find wind loading.
Approach ridges and leeward terrain with caution. Wind can deposit snow 10 times more rapidly than snow falling from the sky multiplying the load on the snowpack. Be very suspicious of any steep slope with recent deposits of wind drifted snow.
Even though there is new snow, there may still be areas of exposed ice and hard snow. If you plan to to go above treeline, take an ice axe and crampons as a precaution. Some windward areas of the peaks were stripped of snow during the February high-wind events, while other areas have retained a 1-2 meter snow depth.
Below Treeline:New snow will hide previously exposed rocks and logs. Coverage has improved, but our mid-winter drought made egress from the backcountry more difficult as many standard routes are a bit burned out, requiring more hiking. Ski area closures and road closures requires even more hiking. Plan accordingly.
Northerly, Northeasterly and Easterly slopes may develop wind slabs. Winds may also cross load other aspects.
Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs are usually confined to lee and cross-loaded terrain features. They can be avoided by sticking to sheltered or wind-scoured areas.
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, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side.
For AZ Snowbowl access updates please refer to https://www.snowbowl.ski/the-mountain/uphill-access/ and www.flagstaffuphill.com.
Always carry the 10 essentials and avalanche rescue gear for wintertime wilderness travel. Submit your observations here. You may save a life!
Weather update Wednesday March 18
We are in the midst of a potent winter storm. a winter storm warning was issued for elevations above 6000’ for Wednesday night March 18th. Between Wednesday afternoon and Friday the 20th, 18"-26" of snow is predicted to fall at treeline. Windy conditions will accompany precipitation with velocities in the 20 mph range, and gusts in the mid 30 mph range. Starting out of the south, winds will shift to the southwest and west as the storm progresses.
Below numbers last updated on March 13th.
Arizona Snowbowl reported a 64" ( 163cm) base at 10,800 feet. Snowslide SNOTEL is reporting a questionable depth of 51" (130cm) at 9,730 feet. So far this winter, 182" (462 cm) of snowfall has been reported at 10,800 feet.
Since Friday March 6th, SNOTEL temperatures have ranged between 49°F on March 12th and 24°F on March 9th. ASBTP station (11,555 ft) reported a low of 15°F on March 9th and a high of 40°F on March 6th.