This advisory expires at midnight.
Tuckerman Ravine has CONSIDERABLE and MODERATE avalanche danger. The Sluice, Lip, Center Bowl, the Chute, Left Gully and Hillman’s Highway have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Lobster Claw, Right Gully, Lower Snowfields, and Little Headwall have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.
Huntington Ravine has CONSIDERABLE and MODERATE avalanche danger. Central, Pinnacle, Odell, and South Gully have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. North, Damnation, Yale, and Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.
AVALANCHE PROBLEM: 2-4″ (5-10cm) of extremely low density new snow will create Storm Slabs which will be easily reactive to human triggers and will sluff in Dry Loose avalanches though the day. Light density Wind Slabs will build in high start zones with their exact locations a moving target as winds wrap around the compass rose when the offshore low pressure system moves into the Gulf of Maine. Starting out the day, expect the same hazard rating as yesterday, generally one down from today’s rating, until incoming snow begins to accumulate. Many areas in both ravines have limited snow coverage, therefore limited bed surfaces and so will struggle to reach their hazard rating for the day. However, the easy triggering of the growing soft wind slabs, especially later in the day and into the evening, makes it difficult to assign a lower rating to these areas. Extremely cold temperatures coupled with increasing and shifting winds will make the Wind Slab problem worse tomorrow.
WEATHER: The NWS has issued a WINTER WEATHER ADVISORY for our area, with 2-4” (5-10cm) expected during daylight hours. An additional 3-5”(8-13cm) is forecasted overnight with an additional 1-3”(3-7cm) tomorrow. Winds will be decreasing and shifting through the day. They will begin from the WNW at 40mph (65kph) this morning and end up from the NE, falling to very slow velocities around 10mph (16kph). Winds will increase and shift again, coming from the NW tomorrow coupled with more new snow. During the day on Friday, winds will move into the 60+mph(100+kph) range increasing the avalanche danger. Temperatures will get very cold as the predicted mercury numbers keep dropping with every model run. Valleys will be colder than upper elevations due to light winds and sinking colder air, but we will still see a mean Jack Frost on the mountain Saturday morning.
SNOWPACK: New snow today should be very low in density with the air mass still below zero F. Delicate crystals may have a hard time surviving the winds until they die down a bit later. Either way, even the dropping winds should be able to transport new snow until summit winds drop into the teens. New slabs will be a mix of broken fragments and intact crystals. This combination will make them cohesive, yet very porous and ever so tender. New Wind Slab development will be thin, but should be very delicate and easy to trigger. It is possible that soft slab densities will be so light that a failure will be very similar to a Dry Loose sluff. Expect the steepest areas, including ice bulges and pitches, to shed new snow through the day. Sluffs may pile up on shelves and below ice pitches such as in Huntington’s Odell gully creating new slab problems. As winds ramp up with more snow on Friday, denser slabs will be deposited over today’s low density snow increasing instability. Expect an increasing avalanche danger trend as we enter the weekend.
- 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 8:05am Thursday, January 2, 2014. A new advisory will be issued tomorrow.
Frank Carus/Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856