Avalanche Forecast for Wednesday, April 8, 2020
This information was published 04/08/2020 at 7:17 AM.
The Bottom Line
The corn crop will ripen once again today as temps rise above freezing at Ravine elevations. Surfaces are currently frozen but should soften through the day, possibly producing conditions ripe for wet loose sluffs. These sluffs should be manageable but will definitely be a factor in steep technical terrain. Expect LOW avalanche danger due to limited size and distribution of this avalanche problem. Area trails will be punchy and postholey, particularly in areas where there has been limited foot traffic. Anticipate icy trails at treeline which will likely require crampons in steep sections due to the recent melt and refreeze. Microspikes may be useful above treeline.
Rescuers should respond with a surgical mask or high quality homemade mask for themselves along with hand sanitizer and/or wipes. Due to wide community spread of the virus, every patient and rescuer may be a coronavirus carrier so act accordingly. In the Cutler River Drainage, we have an extremely limited supply of N95 masks which will be reserved for USFS staff and the patient. As always, rescuers will be turned away without proper PPE.
Yesterday was partly cloudy with a high on the summit reaching 21F on the summit and 43F at Harvard Cabin at 3500’ where 128cm of snow remains on the ground.
Today, temperatures will rebound from its current position as a low pressure system draws warmer air into the region. Currently, it’s 27F at Harvard Cabin and 18F on the summit. Summit temps will warm to the high 20’s F under partly to mostly cloudy skies. NW winds will be light and variable though summits will be higher, in the 10-20 mph range from the NW.
Tomorrow, a stronger low pressure system will bring 8-10” of new snow starting Thursday and continuing into the overnight hours. Lower elevations will likely see a mix of wet snow and rain with an inch total SWE likely in the area. Snow line should fall in the low to mid-elevation band.
Primary Avalanche Problem – Wet Loose
Wet loose sluffing may develop today. Mostly small and relatively harmless but be cautious on slopes over 35º.
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 have most likely reached isothermal temps through the snowpack with no deeper layers of concern despite the presence of some softer layers of melt/freeze recrystallized snow. There was a widespread wet loose natural cycle in the past week which has reduced concerns for any wet loose natural activity. The main concern today is on steep slopes which have remained relatively warm overnight and will warm more quickly and produce a larger sluff. These will be mostly slow moving but should be respected on slopes over 35 degrees.
The Sherburne and Gulf of Slides ski trails remain snow covered to Pinkham Notch.
The Lion Head Winter Route remains the easiest route to the summit from Pinkham Notch but requires an ice axe, crampons (not just micro-spikes) and possibly a rope. This is a mountaineering route and requires solid skills for a safe, timely ascent.
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 04/08/2020 at 7:17 AM.
USDA Forest Service
White Mountain National Forest