Snowpack and Avalanche Information for Friday, May 22, 2020
This information was published 05/22/2020 at 3:17 PM.
NOT THE CURRENT FORECAST
This is an archived avalanche forecast.
The Bottom Line
An isothermal, spring snowpack at elevations above 3500’ is what you’ll find through early next week as warm temperatures continue to melt remaining snow in the Presidential Range. Little snow exists below 3500’. With temperatures expected to remain above freezing at all elevations continuously except for a possible brief period early Monday morning, loose-wet sluff avalanches will likely be the predominant hazard. Sluff avalanches can be dangerous as they entrain skis and drag a person down, though they should not come as a surprise. Unconsolidated wet snow on the surface is the red flag for this avalanche problem. Be mindful of rising temperatures particularly on slopes receiving direct sun.
A melting snowpack also brings additional objective mountain hazards to contend with, including waterfall holes, falling rock and ice, and undermined snow. Review the objective hazards listed in the Forecast Discussion below and keep these in mind as you plan your day.
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!
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.
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.
Daytime temperatures in the Presidential Range have been above freezing for the last 8 days, and the last 48 hours above freezing even at night. Warm weather is forecast to continue at least through the weekend into the start of the week. Wind from the NW will be 30 mph and under, with some clouds around Saturday and Sunday. The long term forecast suggests warm weather, generally sunny or partly cloudy, with no precipitation will continue well into next 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.
Melting snow continues to be the main factor driving snowpack problems for the forecast period. The next 48 hours is forecast to be too warm for the diurnal melt freeze cycles needed for “corn snow” instead leaving a wet, possibly slushy snow surface. Next week may offer a few cold nights of refreeze, though maybe not at ravine elevations. It’s worth mentioning that some locations still hold a deep snowpack, over 100 cm. Melting at mid-day may produce enough free flowing water to rapidly undermine the snowpack, some easily visible and some less apparent due to deep snow. Areas known for this include but are not limited to Pipeline Gully in the Great Gulf, small gullies in the North East corner in Oakes Gulf, and the main drainage in Ammonoosuc Ravine.
As the snowpack melts and recedes, mountain hazards become a significant problem to be aware of. Keep the following spring mountain hazards in mind as you make terrain decisions:
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 05/22/2020 at 3:17 PM.
USDA Forest Service
White Mountain National Forest
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