Expires at Midnight
Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger today. The Sluice, Lip, Center Bowl, Chute, Left Gully, and Hillman’s Highway have Considerable danger. Natural avalanches are possible and human triggered avalanches are likely in these locations. Dangerous avalanche conditions exist; careful snowpack evaluation, cautious route finding, and conservative decision making are essential. Lobsterclaw, Right Gully, the Lower Snowfields, and the Little Headwall have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.
Huntington Ravine has CONSIDERABLE and MODERATE avalanche danger. Central Gully has 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. All other forecast areas have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Heightened avalanche conditions on specific terrain features exist. Evaluate snow and terrain carefully to identify features of concern.
AVALANCHE PROBLEM: Wind slabs are the primary avalanche problem. Loading that occurred since the widespread avalanche cycle following the Thursday storm has continued to produce wind slab instabilities in both Ravines. In the past 18 hours an additional 3-4″, depending on the specific snow plot observed, of snow has contributed substantially to the current wind slab problem. Expect variable conditions from firm older hard slab to newer soft slab currently developing in sheltered locations.
WEATHER: Temperatures have been falling overnight and will continue to do so bottoming out around -15F (-26C) later today. Winds will stay high today, potentially gusting over 100mph. The current trend has been decreasing from a 99mph peak early this morning to a current of about 70mph. As the high builds in, this will change to an increasing trend again this afternoon. New snow will taper as this occurs, but expect blowing snow to effect visibility for most of the day.
SNOWPACK: Another “heads up” day exists for mountain travelers in avalanche terrain today. Overnight, the mountain has received close to 4″ (10cm) on a WNW and W wind from 60-95mph. This has likely caused a fair amount of spatial variability, due mostly to the high wind speeds. Expect to find some areas devoid of new snow while the most protected slopes, with large terrain features, will have soft new unstable slabs particularly on slopes exceeding 40 degree angles facing E and SE. This diversity will likely continue to become more chaotic if the increasing wind velocities play out this afternoon. In our forecasters meeting this morning we were straddling the fence between Moderate and Considerable and decided Moderate most accurately describes today’s problems for some areas. In Huntington’s Pinnacle, Odell, and South; and Tuckerman’s Lobster claw, Right Gully, and Lower Snowfields instabilities definitely exist and should tap all your safe travel skills to negotiate them safely. Ultimately, we decided to call them Moderate due to today’s high winds creating variable, inconsistent surfaces from scoured to soft slab pockets. In Huntington, I would anticipate new snow to have sluffed off steep ice flows and would pay attention to unstable slabs beneath ice pitches in Pinnacle, Odell, and certainly Central which is posted at Considerable. Of course, all of today’s new slab problems have loaded over lingering instabilities from Thursday and Friday. Yesterday’s warm temperatures did help the stabilization process a bit before new snow began, but this warming did not penetrate deeply. This warming, followed by very cold air today, has certainly developed a near surface snowpack temperature gradient that we’ll need to watch. Expect to see a persistent slab discussion over the next couple of days.
- 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 Visitor Center, or the caretakers at Hermit Lake Shelters and Harvard Cabin.
- Posted 8:35a.m. 03-16-2014. 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