Avalanche Advisory for Friday, February 10, 2017

This advisory expires at Midnight.

Huntington Ravine has MODERATE and LOW avalanche danger today. Central, Pinnacle, Odell, South and Escape Hatch have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. North, Damnation and Yale have Low avalanche danger. Natural and human-triggered avalanches are unlikely.

Tuckerman Ravine has MODERATE and LOW avalanche danger today. All forecast areas in Tuckerman Ravine have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. The exceptions to this rating are Lower Snowfields and Little Headwall which have Low avalanche danger. Natural and human-triggered avalanches are unlikely.  Open water and ice remain exposed in the Little Headwall and the creek above. It is skiable but people have been occasionally punching through into water beneath.

AVALANCHE PROBLEM: Stubborn but potentially large wind slabs should be on your radar today if you brave the cold and wind to play in our terrain today. While the summit only recorded 1.5” of snow yesterday, we received closer to 5-6” at Hermit Lake. Our forecast area appears to have received something closer to that higher amount. Strong winds from the northwest built wind slabs last night which will likely be very stubborn to trigger in all but the steepest and most wind sheltered features. We more than likely reached peak natural avalanche activity in the evening last night. Anticipate some further loading today and possibly softer and easier to trigger pockets of wind slab this afternoon as winds abate.

WEATHER: The temperature at Pinkham Notch at this hour is hovering near zero with howling winds while the summit is in the fog with -21F with 90+ mph gusts. The hourly record of wind speeds and direction played out according to the NWS forecast models yesterday. They remained light through daylight hours and slowly shifted from the SW through the west, settling in from the NW and ramping up near nightfall. Overnight, windspeeds were in the 75-90 mph range with gusts to 115mph. Wind will calm through the day and continue from the northwest reaching the 50-70 mph range by nightfall. The temperature will warm to around -7F this afternoon.

SNOWPACK: Winds reached the speed and direction at which scouring typically occurs in northern gullies in Huntington Ravine, in upper start zones in many areas and low in the floor of Tuckerman which likely exposed the hard, icy crust that developed Tuesday night. Frigid temperatures last night and today created conditions for facet development near this crust but the hardness of new wind slab will make the slab bridge across that potential weak layer. Thinner areas of wind slab are more likely to break on early soft storm snow or perhaps weaker areas of faceted crust, but wide propagation is unlikely to occur. Heavily textured and or smooth, firm wind hammered snow will predominate the surface mid-slope. Poor visibility and cold challenges will make assessment difficult today. Looks like a trace to 2” is on its way tonight with 2-4” more tomorrow on moderating winds.

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  7:50 a.m., Friday, February 10, 2017. A new advisory will be issued tomorrow.

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

2017-02-10