Posted 8:00 a.m., Wednesday, March 09, 2011
Tuckerman and Huntington Ravines have Low avalanche danger today. Natural and human triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.
High pressure will remain in place for the start of the day before a southerly flow brings in clouds this afternoon. Today’s weather will be conducive to pleasant conditions on the upper mountain; however, surface conditions remain challenging. The mountain is dominated by a thick and loud breakable crust. My head was ringing after my hike into Tuckerman yesterday. “Crunch, crunch, crunch, crunch……” was the on-going noise I heard on my hike and it was complimented by visions of shooting cracks in the icy surface that eventually gave way under the weight of my body. I did observe some aggressive early stage facet growth below this crust and found myself day dreaming about how long it would take this snowpack metamorphism to eat away at the obnoxious surface layer. You may find some relief to this depending on where you opt to travel. The Lion Head Winter route has been well traveled and folks heading to the Summit via this route will enjoy some of the best the mountain has to offer today. During the heat of the day, south aspects may warm enough to dissipate the crusty layer. Areas near the Lip in Tuckerman Ravine and to some extent the Little Headwall picked up new snow on Monday from wind transport. These wind slabs in Tuckerman represent the only current snow stability issue. While they are isolated and variable, I would still approach them with an appropriate level of caution. It is worth noting that the Little Headwall is undermined and has some open water in the stream bed above. Another potential issue to consider today is the presence of ice dams in Huntington. Recent rains followed by colder temperatures may be causing hydraulic pressure to build. These can release spontaneously or when aggravated by a climbers ice axe or ice screw. Reports coming back from the Sherburne ski trail are grim. The crust makes turning difficult and you can expect to punch through from time to time. If you plan on getting off any of the beaten paths you will need snow shoes or skis. Post hole conditions off trail are excellent. One step off the beaten path and you legs will just disappear!
Another round of weather is on the way and is forecasted to bring 1-3″ (2.5 to 7.5 cm) of snow to the mountains tomorrow…..if it doesn’t change over to freezing rain. Yes, this is going to be another sloppy one. The bulk of the moisture associated with this storm will come on Friday. It looks like 1 to 2″ (2.5 to 5 cm) of liquid will fall in the form of rain in the valleys. It isn’t looking much better for the mountains but we’ll wait for later model runs before we inflate our rafts again. Check tomorrow’s advisory to find out how this weather maker may impact snow stability in the Ravines.
- 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.
Brian Johnston, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856