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!
This is the final summary for the 2019/2020 season! KPAC is especially grateful to the community for the amazing and continued support. THANK YOU!! This was a dynamic season full of varying avalanche problems and although the San Francisco Peaks saw plenty of avalanche activity, none resulted in significant human involved events.
For the week ahead, minor weather systems may impact northern Arizona. These will bring variable snow conditions on the Peaks with avalanche problems specific to aspect, elevation and terrain.
Overall, human triggered avalanches are possible, and natural avalanches unlikely. Renewed wind loading and increased temperatures may elevate the hazard level. Problems to watch out for include: wind slabs on upper elevation ridge lines and gullies, wet loose slides on sun affected aspects, and persistent slab on primarily high elevation northern slopes in relation to buried rain and sun crust layers.
In general, the COVID spring conditions are likely to continue to be variable. This season’s snow total is estimated at 257”, just 3” shy of average. Despite depths of over 200cm of snow remaining on upper north facing slopes, lower elevations are likely to have plenty of rotten snow with rocks and logs lurking just below the surface. If you choose to enter the backcountry this spring be aware of changing conditions, and make conservative decisions.
Sunday, April 12th, brought an unanticipated 12-18” of new snow on the Peaks, which resulted in numerous observations of smaller storm slab and dry loose avalanches. Strong winds followed creating a widespread wind slab problem.
On Tuesday, April 14th, a skier triggered a small R1/D1 soft slab on a 52 degree north facing slope on Fremont, visible from the bottom of Silverton. These problems have mostly stabilized, but continued observations, tests, and conservative travel are warranted, particularly given the current strain on local emergency medical and rescue services
AS a reminder, Snowbowl Road remains closed. Long approaches/egresses to snowy backcountry slopes will be challenging, requiring extra planning, preparedness and effort.
Arizona Snowbowl has suspended all operations, including avalanche hazard mitigation and rescue. Inbound terrain at Arizona Snowbowl is currently closed to all travel.
It bares mentioning that caution in terrain selection and objectives is as important now as it has ever been. It is important to make conservative choices if there is any doubt, as injury in the backcountry may require extensive rescue and medical resources that are already strained in Northern Arizona in the midst of a pandemic. Please consider others in your recreational choices.
Spring travel strategies
Near and Above Treeline:Be aware of wind slabs on north, northeast and easterly slopes, as well as cross-loading in gullies and other terrain features. Although minimal snow is currently available for transport, incoming storms could result in significant snow transport and accumulation.
Use caution throughout the day, especially on sunny slopes, as temperatures increase causing the potential for wet/loose avalanches.
During cold temperatures snow may be incredibly firm and require ice axe and crampons. Expect dramatically changing conditions throughout the day. If you are making the long trek into the backcountry, come prepared. Conditions are likely to be highly variable.
Below Treeline:Significant melting has resulted in many obstacles at lower elevations. Be wary of obstacles that could cause traumatic injury. Expect to find bare ground below 9,000' on northerly slopes, and below 10,500' on southerly slopes.
Most of the wind slab problems from Sunday night's storm have stabilized. However, these slabs may have grown during yesterday's strong SW wind event.
Be aware of hollow sounding slabs located on high elevation ridgelines and gullies which could be reactivated by new wind events, especially if accompanied by additional accumulation.
If a backcountry traveler does trigger a wind slab avalanche, it could overwhelm and step down into a deeper persistent weak layer, creating a larger and more destructive avalanche.
Temperatures are likely to increase over the weekend. During these warming trends, watch for evidence of wet snow instabilities. This includes saturated snow, roller balls and point-release activity.
The structure of the snowpack remains poor and the possibility of loose wet avalanches and wet slab avalanches will increase during rapid warming, especially right after a storm.
Wet avalanche problems can generally be avoided by skiing earlier in the day and staying off of steeper slopes as temperatures warm up and slush becomes more than a few inches deep.
Buried layers of instability associated with multiple rain and snow crusts between 40 and 80 cm deep continue to be an issue.
Additional loading from new precipitation or wind, and/or warming trends could cause this layer to become reactive. Although reactivity has been limited to isolated areas, mostly on north facing slopes, continued awareness and observation of this problem is pertinent to good decision making.
Numerous agencies are discouraging any high risk recreation activities, including backcountry travel.
KPAC is dedicated to informing the public of backcountry snow stability conditions, and providing avalanche education to winter enthusiasts. This will be our last scheduled snow summary. Storm updates are possible if conditions warrant.
KPAC would like to thank the winter enthusiasts of Flagstaff and Northern Arizona for your support, and all of our fundraising sponsors.
This was a banner year for KPAC, with 76 avalanche course students and over 40 awarded scholarships. We look forward to fulfilling our mission again for winter 2020-21.
Please continue to submit observations...and be well, and be safe. THANK YOU!
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!
Updated on Friday April 17th
Early in the week 1 to 1.5 feet of new snow fell, with 1.2 to 2 inches of SWE. The storm was followed by strong winds and cool temperatures. Winds were from the west on Monday the 13th, shifting to the northwest and north on Tuesday ranging from 20-30 mph on ridge tops. Spring-like conditions gradually followed the passing of the cold front with breezy afternoons and warming to seasonally normal temperatures rising into the 40s and 50s F.
Saturday April 18th will bring a dry short wave trough to the region. This will feature southwesterly winds and a chance of snow flurries and even thunderstorms, but little accumulation of snow. More settled weather will follow, however, breezy afternoons, typical of our spring conditions, will continue throughout the week. Several potential weather disturbances will pass through over the next week, but these currently appear to be missing northern Arizona, either to the north or south of us.
Since suspension of operations, Arizona Snowbowl is no longer reporting snow depths. Snowslide SNOTEL reports a snow depth of 50" (127cm) at 9,730 feet. So far this winter, 257" (653cm) of snowfall has been reported at 10,800 feet.
Since Friday April 10th SNOTEL temperatures have ranged between 52°F on both April 15th and 16th, and 8°F on April 14th. Arizona Snowbowl Top Patrol (ASBTP) weather station (11,555') is once again reporting. Over the last week, ASBTP reported a low of 11°F on April 14th and a high of 41°F on April 16th.