Avalanche Advisory for Thursday, January 15, 2015

This advisory expires tonight at 12:00 midnight.

Tuckerman Ravine has Moderate and Low avalanche danger. The Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human-triggered avalanches are unlikely, although unstable snow in isolated terrain features may exist.

Huntington Ravine has Moderate and Low avalanche danger. North Gully, Damnation, Yale, Central, and Pinnacle have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Odell Gully, South, and Escape Hatch have Low avalanche danger. Natural and human-triggered avalanches are unlikely, although unstable snow in isolated terrain features may exist.

AVALANCHE PROBLEM: Continued cold temperatures have worked against stabilization of Wind Slabs in our terrain. These pencil and finger hard slabs are a close second to our primary avalanche problem of Persistent Slabs. You’ll find both of these slab problem types scattered around strong lee areas such as Lip, Center Bowl and Chute in Tuckerman and in parts of Yale and Central in Huntington.  Plenty of old, hard surface exists to travel on in most areas so you can pick a route which reduces your exposure to these slabs.

WEATHER: Looks like a nice day on tap in the high country, with mostly clear skies. Southwest winds in the 15-25 mph, (24-40kph) range with temperatures in the mid-teens F before dropping to around 0F (-18C) tonight. Mostly clear conditions tonight with relatively warm temperatures today will again create conditions counter to the stabilization of our existing slabs.

SNOWPACK: With at least a little precipitation falling on 15 out of the last 18 days and temperatures deep into negative territory, snow has been slow to stabilize. We’d like to say that this nickle and diming snow accumulation is actually giving us substantial gains, but alas we can’t. However the new windslabs of late have been transitioning into persistent slabs that are holding on to their weak layers around both Ravines.  That said, these instability issues are not widespread due to the modest new daily loading only delivering scattered pockets.  You will find faceted crystals varying in size from 1-1.5mm depending on how deeply the January 4th wet snow is buried.  This fact translates directly to the strength of the pressure gradient driving the faceting process.  Under thin slabs you should find larger facets that are weaker than those buried deeper and therefore insulated better from the recent very cold air. Experienced users with avalanche skills should be able to pick out these heightened areas of concern and stick to older surfaces. Careful route selection will certainly play a strong part in staying away from the most recently developed wind slabs and the aforementioned slabs that have just transitioned to “persistent”.  As discussed yesterday, the wide open snowfields in Tuckerman allow more options for a traveler to avoid areas where the stability isn’t good. In Huntington, choke points in the gullies or wall-to-wall slab leave climbers with the choice of going up, going down, or escaping out into rock climbing. The northern gullies of Huntington have the greatest likelihood of harboring unstable snow, while the southern gullies (i.e. Odell, South, Escape) received much less of the recent snow and will have more stability.

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 7:55 a.m. January 15, 2015. A new advisory will be issued tomorrow.

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

2015-01-15 print friendly