Posted 8:10 am, Monday, March 28, 2011
Tuckerman Ravine and Huntington Ravines will have Considerable avalanche danger today. Natural avalanches are possible and human triggered avalanches are likely. There are two exceptions to this rating. The Escape Hatch in Huntington Ravine will have Moderate avalanche danger today. Natural avalanches are unlikely and human triggered avalanches are possible in this area. The Little Headwall in Tuckerman Ravine will have Low avalanche danger. Natural and human triggered avalanches are unlikely in this area.
Today is starting much like yesterday with clear blue skies up high, summit temperatures in the negative numbers (F), and winds that are howling out of the WNW at sustained speeds of 65-80mph (105-129kph). One notable difference is that the air mass has slightly more moisture in it than 24 hours ago and as a result a thin blanket of clouds is hovering just above Hermit Lake. This moisture is driving today’s rise in forecasted ratings as up-slope snow showers are expected in the higher terrain. Accumulations are notoriously difficult to predict under these conditions but the Observatory staff is forecasting 1-3” (2.5-7.5cm) while the National Weather Service is calling for 2-4” (5-10cm). Both are in agreement that winds will remain out of the NW but should decrease to 55mph (89kph) later in the day. Such conditions should create new windslab of concern primarily on slopes with SE aspect such as the Center Bowl through Right Gully in Tucks and the top part of South through Yale Gully next door in Huntington.
We are beginning the day with better overall stability than we had yesterday and the day’s rating are mostly based on the changes expected with today’s forecasted weather. Arctic temperatures have allowed energy to remain in the snowpack but all exposed areas have been getting hammered by the relentless wind. The result is a mix of scouring, windpack and very hard windslab that would not be very reactive to human triggers except where it is thin. Slopes that have a higher degree of protection from WNW winds are the exception and Brian noticed evidence of new avalanche activity on his way into Huntington that wasn’t there yesterday morning. The slope that failed is in an area that we call Broken Leg Gully and is located well down the ridge from Escape Hatch. Unfortunately the Bowl has been obscured by a thin cloud layer all morning and we’d really like to see if the Lip and/or Sluice ripped out overnight as well. Aside from the new snow coming in there are a number of areas in Tuckerman that are on the cusp between Low and Moderate this morning. Hillman’s Highway and Left Gully were both candidates for a drop to Low today but the weather forecast isn’t allowing that to happen.
As mentioned earlier, arctic conditions continue to grip the mountain and yesterday was pretty punishing. Few people tested their luck above treeline and the smarter crowd hung low and sipped tea out of their thermoses. Today is going to be similar. Dropped or unattended gloves blow away in two shakes of a lamb’s tail. Frostbite happens quicker than you realize and hypothermia impairs your ability to recognize when the going has gotten too rough. Even if you’re going for a walk on the lower part of the mountain carry extra gear, travel in pairs, and don’t hesitate to head down to the visitor center for a mug of cocoa. If you do go above treeline the Lion Head Winter Route is filling in and evidence of recent avalanche activity can be found on both sides of the route. The best line up the ridge is marked with bamboo poles. Stay on this path to avoid the more significant avalanche terrain on either side.
- 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.
- This advisory expires at midnight. A new advisory will be issued tomorrow.
Justin Preisendorfer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856