Avalanche Advisory for Thursday, February 9, 2017

This advisory will expire at Midnight.

Huntington Ravine will have HIGH and CONSIDERABLE avalanche danger today. Central, Pinnacle, Odell, and South will have High avalanche danger. Natural avalanches will become likely and human-triggered avalanches, very likely. All other forecast areas in Huntington will have Considerable avalanche danger. Natural avalanches will be possible and human-triggered avalanches likely.

Tuckerman Ravine has HIGH and CONSIDERABLE avalanche danger today. Sluice, Lip, Center Bowl, Chute, Left Gully and Hillman’s Highway will have High avalanche danger. Natural avalanches will become likely and human-triggered avalanches very likely. Lobster Claw, Right Gully, and Lower Snowfields will have Considerable avalanche danger. Natural avalanches will be possible and human-triggered avalanches likely.  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: Wind slabs developing later today will be the primary avalanche problem. Light winds early today will allow new snow to develop into a soft, weak layer over the existing ice crust. West winds will shift northwest and ramp up through the day, ultimately building wind slabs that are likely to overcome the strength of the weak layer beneath. Natural avalanches will become increasingly likely by afternoon in leeward areas of a west or northwest wind with considerable danger even in areas with a southerly aspect. Travel in avalanche terrain later in the day is not recommended.

WEATHER: Currently, winds on the summit are in the 20 mph range from the southwest with 6F on the thermometer. Moderate snowfall began this morning on light winds at 6:30am at Pinkham Notch which is currently at 13F. Bands of precipitation on the radar show that the low pressure system to our south is likely to send the 4-6” snowfall our way pretty easily. A discussion with an NWS forecaster this morning indicates that models are incorrectly showing the wind speed and direction shift occurring 6-8 hours later than actual so make your travel decisions based on the MWObs forecast today. Expect west to northwest loading wind speeds to be blowing by noon and increasing to 50-70 mph by dark.

SNOWPACK: The 8” of snow and sleet capped by a 3cm crust is our bed surface today, at least in areas that did not avalanche. Anticipate the failure layer for avalanches later today to be the new snow falling this morning. Light winds this morning will allow new snow crystals to lay down relatively undamaged while cold temperatures will not improve settlement and bonding. Increasing wind speeds will create increasingly dense wind slabs that will grow in mass until they exceed the carrying capacity of the weak new snow below. Threading the needle today between dust on crust skiing and being swept by an avalanche will require impeccable observation skills, terrain management and a fair amount of luck. Seems like a good day to go to the resort or seek some lower elevation glades or trails in the afternoon. Our forecast areas are currently well developed so be aware of avalanches from places like Dodge Drop and Duchess to run into Hillman’s and Lower Snowfields. Avalanche path extent and the icy bed surface also indicate that dry, slab avalanches today and tonight, while not historically large, could run pretty darn far.

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  8:15 a.m., Thursday, February 9, 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

2017-02-09