Avalanche Advisory for Saturday, February 15, 2014

This advisory expires at Midnight

Tuckerman Ravine has MODERATE and LOW avalanche danger. Right Gully, The Sluice, Lip, Center Bowl, Chute, Left Gully, and Hillman’s Highway have Moderate danger. Natural avalanches are unlikely and human triggered avalanches are possible. Lobster Claw, Lower Snowfields and Little Headwall have Low danger. Natural and human triggered avalanches are unlikely except in isolated areas of instability.

Huntington Ravine has MODERATE and LOW avalanche danger. Central, Pinnacle, Odell, South and Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Evaluate snow and terrain carefully and identify features of concern. North, Damnation and Yale have Low avalanche danger. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEMS:  Wind Slab is the primary avalanche problem today.  These slabs may feel stiff and strong underfoot, but if you find and impact a weakness, a large avalanche might result. Two of the most likely areas where you’ll find softer and easier to trigger slabs are in Tuckerman’s Center Bowl or Left Gully and in and below the dogleg in Huntington’s South Gully. High winds deposited wind slabs throughout our start zones, but particularly lower down on the lower angled slopes. Look for deposits leading up to the steeper parts of our terrain as well as behind and beneath terrain features.   The Fan and Open Book are all but buried by avalanche debris and new wind deposits.  Be wary of the trace to 2″ of new snow forecast later today. As we all know, even small amounts of snow can build quickly into dangerous slabs.

WEATHER:  We are going through a brief period of clear and somewhat placid conditions sandwiched between yesterday’s full on winter brutality, and tomorrow’s extreme wind velocities.  For today, a slow building wind from the SW will increase to about 30mph before shifting from the NW overnight.  Snowfall will creep in as the day continues with up to 2” (5cm) and an additional 1-3” (2.5-7.5cm) overnight.   The second very important weather concern this holiday weekend will be the bomb cyclogenesis, or an enormous bomb dropping pressure with the exiting low.  This will lead to a very strong pressure gradient  on Sunday delivering winds in excess of 100-115mph!  When this bomb phenom sets up meteorologists look very closely at their forecasts and think hard about what extreme events could occur. These winds coupled with sub-zero temperatures should throw up every red flag you have saying mountain travel today could be a life changing event. Literally. I would think very very very hard before attempting a range traverse this weekend.

SNOWPACK: With snow totals around a foot and a half and winds from just about every point on the compass rose, this last storm left wind slabs on a variety of aspects. Summit wind speeds gusted over 100 mph (160 kph) for a 4-5 hour period yesterday afternoon, pummeling the heavy snow (12-16%) and moving it all around the mountain. 1F wind slabs exist even low on the mountain and in the woods. I suspect today is one of those days when, due to the deceptively firm travelling surface, you can be lured into much bigger terrain than you might go into if the snow was softer and more obviously weak. Think of the wind slab as a piece of damaged plywood spanning a trench. Lucky people may cross uneventfully, while some unlucky soul may find the weak spot and get a big surprise.

Holiday weekends are typically busy, which means more triggers running around looking for snow weaknesses. Expect people above you and under you, respect both.  Be thoughtful about showering dinner plates down gullies as you move over brittle ice. Conversely be very cautious climbing under others, or better yet avoid it.  The same goes for avalanche concerns. The aforementioned extreme winds coming smack in the middle of the holiday weekend is the big news.  This is making the hair stand up on the back of our necks a bit.  Above treeline travel tomorrow, as it looks right now, is not prudent.  Start to consider other options now so you aren’t duped into giving it a shot because you don’t have an acceptable plan “B”.  We will send out updates to this wind event on Twitter and Instagram @mwacenter, check us out.

Please Remember:

  • 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. 2-15-2014. A new advisory will be issued tomorrow.

Frank Carus, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856

2014-02-15 print friendly