Avalanche Advisory for Thursday, January 25, 2018

Huntington Ravine has LOW avalanche danger. All forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.

Tuckerman Ravine has MODERATE and LOW avalanche danger. Lip, Center Bowl, Chute and Left Gully have Moderate avalanche danger. Heightened avalanche conditions exist on specific terrain features. Evaluate snow and terrain carefully. All other forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.  The Little Headwall is mostly open water or waterfall ice and not rated.

AVALANCHE PROBLEM: Lingering wind slabs will be the primary avalanche problem today. Areas of mostly firm but potentially unstable wind slab exist in steep, lee terrain sheltered by recent NW winds. These slabs are on the smaller side but the consequences of an avalanche on our slick bed surface could be severe. Evaluate the snow carefully. Most of the terrain consists of a hard, gray old surface of refrozen, rain saturated snow. This is especially true in low rated zones where most of the 2.5” of snow which fell in the past 48 hours was scoured off of the terrain by high winds. Still, areas with a low rating may contain pockets of wind slab on isolated terrain features so assess these slabs for signs of instability or avoid them altogether. In Tuckerman Ravine, the run in the headwall known as The Lip contains an unusually nasty fall potential due to the 20’ crown face in the middle of the run. The affected area is in the fall line of the Tuckerman Ravine Trail making the consequences of a fall on this slope particularly dangerous. The refrozen and hard nature of the existing snowpack makes crampons, ice axe and microspikes useful, if not required, to safely climb any route that takes you above treeline.

WEATHER: Currently, the temperature at Hermit Lake is 3F and -6F on the summit with winds from the NW at 60 mph. Cold, dry conditions will persist today with below normal temperatures around -10F on the summit and NW wind increasing from 50-70 mph to the 65-85 mph range. Gusts could reach 100 mph. About an inch of snow was recorded early yesterday morning bringing the total snowfall recorded since the most recent rain to 2.5”. The next opportunity for snow appears to be Sunday when a low pressure system moves up the coast. Until then, count on dry but warming weather on Friday and Saturday.

SNOWPACK: Two warm spells with copious amounts of rain this month have turned our deeper snowpack into a rock hard mass. The large wet avalanche that blew out the waterfall in the Lip area is reforming ice but remains mostly unchanged with a large debris pile filling the floor of the Bowl. Snow and ice climbs in Huntington are in fine shape with plenty of water around to form new ice.

The Sherburne Ski Trail is rideable but barely concealed rocks and other rain damaged sections exist.

Please Remember:
• Safe travel in avalanche terrain requires training and experience. This bulletin 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 Harvard Cabin.
• Posted 7:45 a.m., Thursday, January 25, 2018. A new advisory will be issued tomorrow.

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

2018-1-25