This advisory expires at midnight.
Huntington Ravine has MODERATE and LOW avalanche danger. Central, Odell, South, and Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate terrain and identify features of concern. North, Damnation, Yale, and Pinnacle Gully have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain.
Tuckerman Ravine has MODERATE and LOW avalanche danger. Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. Heightened avalanche conditions exist on specific terrain features. Evaluate terrain and identify features of concern. Lobster Claw, Right and Left Gully, and Hillman’s Highway have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain.
AVALANCHE PROBLEM: With another warm day ahead of us, Wet Slab and Loose-Wet avalanches will be on our radar. Warm air temperatures and sunshine may test our snowpack today. There are two areas of new snow that present the most concern. The first of these is the areas of wind loading that occurred on Wednesday night and Thursday. These wind slabs formed on WNW winds and are largely in lee areas of our steepest terrain. The second layer of new snow presenting a concern is the areas of sluff deposit. Again, primarily under the steepest terrain, these two layers of new snow may see a strong period of warmth today that could test their bond with the old surface or soft snow interfaces underneath. Areas of old surface may soften up today and could present loose-wet sluff problems today.
WEATHER: Yesterday was a beautiful January day on the hill. Calm winds, clear skies and an inversion made for almost a spring-like day in the Ravines. The overnight low on the summit was 25F and at Hermit Lake 15F. Today, winds will shift from W to NW and hover in the 45-60mph range. Temperatures will stay in the 30s for the morning before falling into the 20s as the day progresses. Overhead moisture may bring in mixed precipitation at some point during the afternoon and into the night.
SNOWPACK: Several layers of the snowpack will come into the play today. The old surface melt-freeze crust from January 12 will either soften in areas where it is exposed (particularly areas with southern exposure) or provide a bed surface in areas where new snow exists on top of it. As mentioned in the avalanche problem discussion, this new snow exists in several forms: small pockets of dry loose snow low in gullies and in the trees, areas of wind slab that saw some sun yesterday and areas of sluff deposit that also saw some sun yesterday. What happens today will largely depend on how warm the snowpack becomes. With temperatures in the mid-30s and plenty of sunshine, we may see some areas of solar gain. That being said, winds in the 50mph range can negate this and may keep the snowpack cold. Keep an eye on the sky but also your hand in the snow when in the field today. If things really get warm, today will be a heads up day, especially if the interface of the old surface and new snow heats up.
The Lion Head Winter Route is open and the most direct route to the summit from the east side of the mountain. Please be on the lookout for machine traffic on the Sherburne.
- 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 8:15a.m., Saturday, January 21, 2017. A new advisory will be issued tomorrow.
Helon Hoffer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2713