If you are recreating, please do so responsibly. This includes following social distancing requirements, not taking actions that risk pulling emergency service workers away from the important work they’re doing, or compromising their ability to continue that work.
To prevent spread of COVID-19, please do not travel to Flagstaff for recreation. If you are local to Flagstaff and choose to head to the backcountry, every effort should be made to avoid injuries. Now is not the time to visit a hospital which may be overwhelmed due to COVID-19. Know the conditions and know your limits!
Natural avalanches are unlikely, human triggered avalanches are possible. As the weather changes, expect corresponding changes in the avalanche hazard.
Currently Snowbowl road remains closed for broader community health and EMS resource management. Long approaches/egresses to snowy backcountry slopes will be challenging and require extra planning, preparedness and effort. Arizona Snowbowl has suspended all operations, including avalanche hazard mitigation and rescue. Treat inbounds terrain as uncontrolled backcountry, which is currently closed to all travel.
New wind slabs near and above treeline, and a persistent slab problem on NW, N and NE slopes above 11,000' may also present potential hazards to backcountry skiers and boarders. 40" of snow accumulated above treeline between March 19-23, creating reactive wind slabs: https://snowpilot.org/sites/default/files/snowpit-profiles/graph-24293.jpg
Light snow accumulation of 2-4” and a significant cool down are predicted on Friday March 27th with a quickly passing cold front.
Click read more for springtime travel advice and recent avalanches.
spring travel strategies.
- There was a relatively small soft slab natural-avalanche in Snowslide Canyon Bowl, likely on March 18 or 19th. See photo below.
- On Saturday morning, March 14, while using explosives in a closed area, AZ Snowbowl Ski Patrol triggered an avalanche on a northwest slope near 11,900 feet. 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. The failure occurred within frozen needles resting on the March 11 rain crust.
- No human triggered slab avalanches reported in the backcountry this season.
Near and Above Treeline:40" of new snow from March 19-23 has been wind transported from south and southwest winds, creating potentially dangerous wind slab on leeward slopes (E and NE) above treeline.
KPAC observers found reactive wind slab on Thursday, March 26, from an east facing pit in Snowslide Cirque (11,900’). Both compression tests and an extended column test showed low to moderate strength with high propagation propensity. This condition, no doubt, resulted from last week’s strong southwesterly and westerly winds in the high teens and twenties, gusting above forty miles per hour.
The previously identified weak layer above the March 11th rain crust can not be completely ruled out as a persistent slab trigger. Stability may have improved overall, but dangerous pockets may still exist.
Pits dug on NW-N-NE slopes above 11,000' indicate a persistent slab problem. The weak layer is comprised of needles/facets resting on top of the March 11 rain crust, about 60 to 70cm (2-3’) below the snow surface. It may be possible for a human to initiate a failure in this persistent weak layer, and the consequence could be a large destructive avalanche.
Despite the new snow, wind stripping may have 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 were no doubt stripped by strong winds last week, while others have retained 3-6 feet of snow depth.
Below Treeline:Expect to find melt/freeze crusts on most sun exposed aspects at lower elevations. New snow will hide previously exposed rocks and logs. Coverage has improved, but high variability in snowline elevation from storm to storm has resulted in corresponding variability in coverage at lower elevation. Plan accordingly and be ready to accept some hiking as part of your tour. Current navigable snow tapers to the ground at @ 10,000' on south facing aspects.
March 20 and 21 stability tests on NW, N and NE slopes above 11,000' indicate a persistent slab problem. The weak layer is comprised of needles/facets resting on top of the March 11 rain crust, about 60 to 70cm (2-3’) below the snow surface.
Human triggered avalanches are possible in this persistent weak layer, and the consequence could be a large destructive avalanche.
The take home message is to keep your avalanche eyeballs wide open, because this persistent slab problem may be of low likelihood, but high consequence.
Northerly, northeasterly, and easterly slopes may develop wind slabs. Winds may also cross load other aspects. Winds shift to the northwest tonight, potentially loading other aspects.
Wind typically transports snow from the upwind side 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.
Temperatures are forecast to warm dramatically after the weekend. Watch for wet snow and destabilizing slabs. It is time to move off a slope when slushy wet snow becomes more than a few inches deep.
For AZ Snowbowl access updates please refer to https://www.snowbowl.ski 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 updated Friday March 27th
The early week storm systems delivered an additional 14” of fresh snow above treeline, and mixed precipitation below treeline caused by fluctuations in the freeze line elevation. This addition brought a total of 40” of snow at 10,800' in the last 10 days. As the system dispersed, moderate to strong winds out of the west brought bluebird post storm conditions to the Peaks, with high potential for transportation of snow above treeline.
This next week brings continued excitement with a cold spell and potential light to moderate precipitation to northern Arizona. A digging low from the north will come to the area Friday through Saturday morning, followed by a trailing short-wave trough. The freeze line will drop to 4,500 feet.
Currently a 10-20% chance of precipitation is in the forecast for early in the workweek. Winds will stay in the moderate range (15-25 mph) out of the west. Temperatures at treeline will climb into the low 40’s F on Tuesday, and a warming trend continuing with spring-like weather.
Arizona Snowbowl is no longer reporting snow depths. Snowbowl ski patrol reported 40" inches of new snow at 10,800 feet since March 19th. Snowslide SNOTEL reports a snow depth of 57" (145cm) at 9,730 feet. So far this winter, 234" (594cm) of snowfall has been reported at 10,800 feet.
Since Friday March 13th, SNOTEL temperatures have ranged between 52° F on March 23rd and 5° F on March 20th. ASBTP station (11,555 ft) is not currently reporting information . Arizona Snowbowl Little Spruce (ASBLS) station (9379’) reported a low of 14° F on March 20th and a high of 31° F on March 22nd and 24th.