Avalanche Forecast for Thursday, April 25, 2019
This information was published 04/25/2019 at 6:47 AM.
The Bottom Line
Long, sliding fall potential this morning, followed by wet loose avalanches and increasing spring hazards this afternoon should be on your mind as you look for good turns. LOW avalanche danger exists today due to heavy sluffing in new snow that fell last night and more limited sluffing in older snow that will be softening through the day. There have been many learning opportunities this season regarding the severity of punishment that can be meted out for small mistakes, so pay close attention to your surroundings and your educated intuition.
Freezing conditions returned overnight to the summit and, to large extent, middle elevations. Clearing skies, sunshine and low wind speeds will allow the temperature to quickly rebound above the freezing mark this morning. Expect a high temperature around 35F on the summit and warmer in the Ravines. Overnight temperatures on the summit will remain near or just below freezing. Rain and mixed precipitation return tomorrow with the potential for 2-4” of snow, with rain at lower elevations, on Saturday. Today is the day to call in sick.
Primary Avalanche Problem – Wet Loose
An inch of new snow plus softening old snow will create relatively harmless sluffing today, if well managed. Consider what is in your fall line, especially any crevasses, moats around rocks and cliff bands. These can be serious terrain traps.
What is a Wet Loose Avalanche?
Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
We’ve received less than half the average snowfall for the month and we are ¾ of the way through. Most of the precipitation has fallen as rain which makes it hard to believe that we are 2” below normal for that type of precipitation as well. In any case, the continued warm nights combined with rain are rapidly bringing spring conditions to the mountains. Rockfall, icefall, moats, crevasses and undermined snow over streams are all players in this mountain arena. You can easily reduce your risk by giving these hazards a wide berth and by scouting your line carefully. Warm temperatures today and tomorrow will continue the melting and contribute to these hazards.
Significant melting has occurred, bringing springtime objective hazards to the forefront. If you are in the mountains today be watching for:
- Opening streams
Undermined snow that could easily collapse
Glide cracks on snow slopes
Falling ice and rock
The Sherburne and Gulf of Slides ski trails are no longer completely snow covered to Pinkham Notch. Expect ice patches, open stream crossings, rocks and bare patches. We will likely be closing a lower section of the Sherburne soon in order to prevent destructive erosion of the trail. When we do, please do your part to preserve the quality of the trail by removing your skis and hiking the rest of the way down to Pinkham on the Tuckerman Ravine Trail.
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.
Recent snowpack and avalanche observations can be found here and on Instagram. Your observations help improve our forecast product. Please take a moment and submit a photo or two and a brief description of snow and avalanche information that you gather in the field.
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 04/25/2019 at 6:47 AM.
USDA Forest Service
White Mountain National Forest