Snowpack and Avalanche Information for Monday, May 04, 2020
This information was published 05/04/2020 at 7:00 AM.
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.
Avalanches will become possible as favorable conditions exist for upslope snow showers at upper elevations over the next two days. Watch for wind slabs developing in eastern ravines where slide paths are still fully developed top to bottom. The size of any new windslabs will likely be limited by low snow totals. If the upper end of the possible 6” snow falls, slabs could be large enough to carry and bury a person, especially Monday night and Tuesday when colder air lowers the freeze-line elevation.
Rapid warming of new snow may occur on Wednesday as skies clear and temperatures rise above freezing creating the possibility of wet snow avalanches.
Mixed wintry weather at the later end of the week brings the chance for snow showers and new wind slabs forming in lee terrain, wherever that may be.
Wind slab development over the next 48 hours will be dependent on snow totals and temperatures. If forecast snow showers lack intensity, or warm air brings rain at ravine levels, wind slabs may be small and/or unreactive with limited significance.
Overall, there’s still lots of snow at mid and upper elevations. Gray Knob snow plot reports 35” of snow depth on May 4 and Harvard Cabin reported 70” on April 30. After 0.8” of rain at all elevations on May 1st , and multiple warm days the snowpack is on the way to becoming isothermic with avalanche concerns limited to events of new snow and the possibility of wet-loose sluffing.
Regardless of an avalanche problem, with blowing snow and possible limited visibility keep the following spring mountain hazards in mind as you make terrain decisions:
- Moats and other deep melt holes
- Waterfall holes
- Opening streams and undermined snow
- Glide cracks
- Falling ice and rock
- Long sliding falls
- Sliding falls, even short ones
Travel has been difficult with untracked and unpacked snow at mid and upper elevations. Flotation in the form of snowshoes or skis is highly recommended, even on normally well-traveled trails.
The Sherburne and Gulf of Slides ski trails are no longer fully snow covered to Pinkham Notch. Expect sections of dirt, mud and rocks to grow as the snow melts from warm temperatures.
Details on daily snowfall totals, precipitation type, total depth of snow and other information can be found on our page devoted to snow study plot data. Click here to check it out.
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 05/04/2020 at 7:00 AM.
USDA Forest Service
White Mountain National Forest