Snowpack and Avalanche Information for Sunday, May 10, 2020
This information was published 05/10/2020 at 8:03 AM.
NOT THE CURRENT FORECAST
This is an archived avalanche forecast.
The Bottom Line
Winter conditions have returned with summit temperatures dipping into the single digits and 12” of new snow Friday night and Saturday. New wind slabs developed Saturday and will continue to form today as very strong northwest and west winds load east facing terrain. The new snow and loading fell on an icy, smooth bed surface with the potential for human triggered, hard slab avalanches. Strong wind speeds will continue today, first from the northwest then west, resulting in a mix of scoured terrain and hard wind slabs with the potential for more natural avalanches in wind sheltered terrain.
MWAC has moved to a Snowpack and Avalanche Information bulletin (known in prior years as a General Bulletin) until the end of the season. Snowpack and Avalanche Information is issued when unstable snow may exist within our forecast areas but after 5-scale avalanche forecasts have stopped. Please remember that avalanches can and do occur after 5-scale avalanche forecasts have ceased! A new bulletin will be released by Friday, earlier if conditions warrant.
On March 30th, the USFS MWAC took a tactical pause in forecasting operations. Since that time, forecasting and closure monitoring have continued, though forecasts were sent directly to local mountain rescue organizations only. As the public continues to recreate and winter conditions persist in the mountains, it is apparent that current snowpack and avalanche information could be helpful in reducing risks. Please realize that volunteer rescue resources are currently limited due to concerns about community spread of the coronavirus.
Tuckerman Ravine, Huntington Ravine and the Gulf of Slides will remain closed to all use until May 31 and possibly later as winter conditions and deep snow remain.
Temperatures will warm Monday and rise above freezing at middle elevations and below. Up to a half inch of rain, freezing rain and wet snow will weaken the existing wind slabs to some degree. Higher elevations are likely to see mostly snow through Monday night. Clear skies and cold air temperatures are on tap for most of the week.
Despite the date on the calendar, new snowfall and winter conditions are possible during any month of the year at higher elevations in the Presidential Range. Spring and early summer bring rapid changes to our upper snowpack, with conditions often changing by the hour. Plan accordingly for these changes by reading the weather forecast before you head out (MWObs Higher Summits and NWS Hourly forecast).
One tool to help reduce the chance for unwelcome surprises is the hourly weather information produced by MWObs summit staff. The NWS displays the hourly data going back 7 days here.
Recent snowfall earlier this week was underwhelming and did not do much more than create some thin pockets of new snow over a hard, refrozen surface. Our existing snowpack is mostly isothermal and icy on the surface at mid and upper elevations that have been scoured by strong winds. You will also find deep drifting above treeline. Travel conditions in a single day could vary from the need for floatation in rotten lower elevation snow as temperatures warm or thick, hard mid-elevation wind slabs which demand crampons and ice axes on hard névé or ice.
Overall, there’s still lots of snow at mid and upper elevations (210cm at Hermit Lake!) with none of the typical spring crevasse, moat and icefall hazards yet to emerge. This also means that there are expansive and connected slopes which could produce large avalanches. Don’t put away your beacon, probe and shovel just yet!
Safe travel in avalanche terrain requires training and experience. This forecast is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel.
Avalanche danger may change when actual weather differs from the higher summits forecast.
For more information contact the US Forest Service Snow Rangers, AMC visitor services staff at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or seasonally at the Harvard Cabin (generally December 1 through March 31). The Mount Washington Ski Patrol is also available on spring weekends.
Posted 05/10/2020 at 8:03 AM.
Frank Carus, Lead Snow Ranger
USDA Forest Service
White Mountain National Forest
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