This advisory expires at 12:00 midnight.
All forecast areas of Tuckerman and Huntington Ravines have High avalanche danger. Very dangerous avalanche conditions exist. Travel in avalanche terrain is not recommended. Natural avalanches are likely and human triggered avalanches are very likely.
AVALANCHE PROBLEM: If you are heading out to avalanche terrain today, you may want to re-read the preceding paragraph. Wet slabs, wet loose, and persistent slabs are all in the mix as potential avalanche problems today. At the time of this writing, our avalanche paths are sitting well into the Considerable range. Increasing avalanche danger during this weather event will push the hazard up into High danger. There is a fair amount of uncertainty in how much precipitation will fall and exactly what type. But regardless of how this exactly plays out and regardless of where exactly we are on the danger scale, travel in avalanche terrain today would best be avoided.
WEATHER: A wintery mix of precipitation is forecast to fall across the mountains today. This event has already brought a few inches of snow. Currently at Hermit Lake there is a steady stream of sleet pellets falling from the sky. Temperatures are expected to warm through the day, so I expect we will see this turn over to rain at most elevations. The very top of the mountains may have only sleet or freezing rain, but I expect this freezing line to be well above our forecast areas, meaning that the ravines will see a fair amount of rain today.
SNOWPACK: The surface layer is now a few inches of wet snow being loaded further by ice pellets and soon rain. This leads to the potential for wet loose avalanches, particularly in very steep terrain such as the gullies of Huntington. As rain penetrates the snowpack, adding to moisture developed during yesterday’s warmth, we may start to see upper layers of slab releasing as wet slab avalanches. As usual, our snowpack has a variety of layers near the surface. These will continue to lose strength during the day. I would expect any avalanches produced by this problem to be on the smaller side, though the consequences could be significant if you are in the wrong place.
The final piece of today’s puzzle is persistent slab avalanches. These have been in our minds (and in the advisories) for much of the season as back-burner potential problems. Yesterday this potential was realized in a big way. The southeast snowfields of the summit cone were triggered in the afternoon. The failure layer was a layer of facets beneath the January 11 rain crust. In many areas of Tuckerman this layer has been minimized by avalanche activity long ago, but there is a peppering of locations where we believe the layer is intact. The largest of these is the Lip and Sluice, as well as other parts of the Tucks headwall and Central Gully in Huntington. We will hopefully get some pictures and a write up about yesterday’s slide on our site today.
OTHER HAZARDS: Undermined and collapsing snow bridges have snuck up on us as a potential issue. This is mostly a concern for people looking to ski the Little Headwall or brook above. Be careful around any stream bed today.
- Safe travel in avalanche terrain requires training and experience. This advisory 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.
- Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast.
- For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin.
- Posted 8:30 a.m. 3-30-2014. A new advisory will be issued tomorrow.
Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856