This advisory expires at midnight.
Tuckerman and Huntington Ravine have CONSIDERABLE avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Dangerous avalanche conditions exist; careful snowpack evaluation, cautious route finding, and conservative decision making are essential. Expect an increasing avalanche danger today and overnight.
AVALANCHE PROBLEM: A WINTER STORM WARNING is in effect. Problem #1 will be shared between Storm Slabs and Wind Slabs today. Wind slabs that developed over that past 36 hours will be the leading problem this morning followed by new Storm Slabs and new Wind Slabs this afternoon. Heavy snowfall will increase load and instability later today bumping the potential for natural and human triggered avalanches. New snow slab failure could step down into the Persistent Slab weaknesses that have been difficult to trigger as of late. This secondary persistent problem is mostly a concern for the ultimate size of an avalanche. This is due to new snow avalanches that may be more load and stress than these lower facet weaknesses can take, causing failures to step down to deeper slabs.
WEATHER: Today’s winter storm should bring 18-24+ inches ( 45-60+cm) of snow beginning this morning, picking up this afternoon, and into tomorrow. This will start off with a WSW wind quickly moving counter clockwise through the SW, S, and eventually from the SE increasing in speed from 20-30mph this morning to 40+mph later. Snow will increase in intensity and become a full rager overnight. Temperatures will fall from a high of 20F today to -10F tonight, with an increasing and shifting wind. Winds will continue to wrap through the E into the N during darkness and blow over 70mph. Thursday will be cold with the wind shift continuing to the NW.
SNOWPACK: To keep this discussion on point I will avoid much of our deeper issues as they will become moot compared to today’s storm problems, and the loading from the last couple of days. Anticipate the greatest instabilities, as well as natural and human triggered avalanche potential, to occur on faces with a northerly facing component today. As winds today rotate through the S expect slopes such as the Chute, Left Gully, Hillmans, and the Boott Spur gullies in Tuckerman; as well as Odell, South, and the Escape Hatch gullies in Huntington, to see the heaviest loading. New snow will start with a lighter wind allowing it to load into the terrain deposition as a light density layer. This will likely act as the weak layer for future avalanches as densities become heavier with increasing wind velocities. As today’s storm continues overnight, and winds wrap all the way around the compass rose, expect heavy loading. This will initiate as cross loading, due to an E wind, then major loading on slopes facing S, and then SE and E tomorrow.
We will be bumping the ceiling of the Considerable ratings later today and will move towards HIGH during the overnight and EXTREME avalanche danger sometime Thursday morning if the storm plays out as forecasted. It is absolutely not a good day to be be running late in your mountain adventures. Get home early and hit the hot tub.
- 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 800am 3-12-2014. A new advisory will be issued tomorrow.
Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856