Avalanche Advisory for Friday, February 14, 2014

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 PROBLEMS: My personal favorite avalanche problem will be here in abundance today, STORM SLABS. The avalanche conditions we expect to have on the mountain today are of the sort that should make you want to avoid avalanche terrain altogether. We regularly talk with people who are going to the bowl just to “take a look” or “check it out”, and these people often don’t believe they are going into harm’s way. Let’s be clear. Doing this is indeed putting you in a dangerous position for naturally triggered avalanches that will be extending farther into to bottoms of the ravines than they have traveled yet this season.  Stick with terrain that is well away from steep slopes, such as the Sherburne or one of the many lift-serviced areas.

WEATHER: Heavy snow fell last night, leaving behind about 13″ of snow across Mt. Washington (34cm at Hermit Lake, 35cm at the summit). Densities at the Hermit Lake elevation are in the range of 10% at the start of the storm (*see note below) up to 16% in the latter half. Snow is expected to continue through this morning, dropping an additional 4-6″ as this low pressure system pulls farther out to sea. As this happens, winds are expected to wrap around so they’ll be coming from the NW, and increasing in velocity to 60-80mph+ (100-130kph). Winds have been much lighter than this since midnight, so much of the newly fallen snow is just sitting, waiting for increasing winds to load it into the ravines. The shift in direction is expected to come this morning, which will give us ideal loading conditions for much of the daylight hours.

SNOWPACK: What’s going on deeper in the snowpack will have very little to do with today’s avalanche danger. We can expect some large avalanches involving only recent snow. An avalanche may step down into older hard slab, and maybe even rip out down to the mid-January rain crust. This would be a horrible scenario if you were involved in this, but if you want to see the floor of Tuckerman fill in with snow, it might not be a bad situation.

It will be important to recognize today that danger will be increasing as the day progresses,but at first light this morning we are already at the point where traveling in avalanche terrain isn’t recommended. However, I should mention that some forecast areas may not reach high danger today. These include the Little Headwall and Lobster Claw. The Little Headwall had open water not long before this storm and the streambed in and out of the area would be heinous to travel through. Lobster Claw also had very little snow in it, but we expect shifting winds through the N to deposit a lot of snow in this area, as well as Right Gully. While LC might not make it to High danger today, I do expect it to push into Considerable danger due to heavy wind loading.

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 8:00 a.m. 2-14-2014. 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

*Note: The storm snow began as lighter density crystals and gradually transitioned to heavier snow. This morning the bottom 14cm of the new snow was sampled, giving a density of 13%, the upper 18cm measured 16%. I believe this 13% number is higher than what actually fell due to the compaction that took place as heavier snow piled up on top of the light density lower layer, but have good confidence in the the 16% density found in the upper half.

2014-02-14 Print friendly