This advisory expires at midnight Tuesday 1-24-2012.
Tuckerman and Huntington Ravines have Low avalanche danger today. Natural avalanches and human triggered avalanches are unlikely. The Lobster Claw, the Lower Snowfields, and the Little Headwall are not posted due to an overall lack of snow. Forecasts for these locations will begin when warranted; however, you should be aware that avalanche activity may occur within these areas before forecasts begin.
As if this winter hasn’t made us suffer enough, last night the White Mountains region enduring a drenching January rain event. Mt. Washington’s summit received about 0.5” (13mm) of melted precipitation, mostly in the form of freezing rain and rain, while down at Hermit Lake about 0.75” (19mm) of precipitation fell. About the only good thing I can say about this event is that it mostly happened at night. Some of the Hermit Lake precipitation was snow during the daylight hours, but the bulk of the event was rain overnight. As of this morning temperatures have begun to fall. Currently the freezing line is just above the ravines, but as the day progresses this will drop, locking up the mountain in an icy crust.
The end result of this weather pattern will be a very stable snowpack. However, early birds and go-getters should realize that we are at the tail end of a natural avalanche cycle, with a rating of High less than 12 hours ago. As the lockdown takes place the trend is undoubtedly toward stability, but there will be a window of time before everything is absolutely stable. There is currently a lot of moisture in the snowpack. This has had a reasonable amount of time to percolate downward through drainage channels it created within the snowpack. The chances that some of this free water may still reach a cold, dry, weak layer and trigger an avalanche are slim, but they do exist. Similarly, a person may penetrate deeply enough into some sloppy wet snow and hit a weak layer. The best window for this taking place is right now, while ravine temperatures are above freezing or shortly thereafter. On the whole, I don’t believe either of these scenarios presents enough likelihood to warrant more than a Low rating, especially considering the trend toward better stability as the day continues. But remember that Low avalanche danger does not mean the same as no avalanche danger or that there is nothing at all you need to pay attention to. If you want to avoid this potential, just wait a few extra hours for the temperatures to continue to drop.
It seems as though we go through a period like this every winter. One thing that sticks out in my mind after the midwinter thaw is how slick and slippery the steep slopes can become. If you’re planning to be here over the next few days, bring your ice axe and crampons. You’ll need to know how to use them proficiently as well. With the thin snow cover, numerous hazards remain exposed, making a sliding fall a very unwelcome proposition. There’s also a chance for a small amount of snow to fall before tomorrow, which may create stability concerns if it loads onto a smooth ice crust. Stay tuned for more on that tomorrow.
The Lion Head Winter Route is now open. This is a steep route; an ice axe and crampons are highly recommended for safe travel. Please avoid the summer Lion Head Trail due to avalanche risk. The Sherburne Ski Trail had decent coverage, but nothing erodes snow faster than a rainy and foggy night. I expect it will be quite icy by the end of the day with numerous exposed rocks.
- 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 8:25am. 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