Avalanche Advisory for Saturday, March 17, 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. Sluice, Lip, Center Bowl, and Chute have Moderate avalanche danger. Evaluate snow and terrain carefully to identify features of concern. All other forecast areas have Low avalanche danger. Watch for unstable snow on isolated terrain features.

AVALANCHE PROBLEM: Our avalanche forecast today is driven by the legendary, howling winds that hammer Mount Washington. Strong winds overnight and this morning have scoured much of our terrain but have also left firm and stubborn wind slabs in their wake. These wind slabs are the primary avalanche problem today. The moderate rated terrain in the headwall area of Tuckerman Ravine harbors the largest wind slabs with pockets of wind slab elsewhere. In low rated areas these slabs will generally be on the smaller side and should be pretty easily avoidable, though it will require good micro-route finding skills. Though these firm wind slabs will be the primary avalanche problem, the main environmental challenge you’ll face today is cold temps and wind chill. You’ll need the luck o’ the Irish to avoid frost nip if you venture above treeline today.   

WEATHER: A little over an inch of new snow was recorded at the summit in the past 24 hours with 6cm recorded at Hermit Lake. Due to the strong winds, even the tree sheltered snow plot was heavily wind effected. Winds overnight raged near 90 mph for almost 7 hours with gusts in the high 90’s or 100mph for 3 hours. A peak gust out of the WNW hit 111mph. Wind direction will continue from the NW but diminish through the day to the mid 50’s mph. Temperatures will be around -5F for a high today on the summit. Another inch or snow of snow could fall mid-day and may contribute to low visibility conditions primarily caused by summit fog. Goggles, face protection and a good whiteout navigation plan will be key today.

SNOWPACK: The 30” of snow which fell primarily on Tuesday through Thursday is wind effected to say the least. Stiff wind slabs exist even below treeline. The nor’easter responsible for the snowfall lingered and continued to drop snow in the region. As winds finally wrapped around to the west while the low exited the area, available snow on the ground was blown into our east facing terrain, resulting in wide spread natural avalanche activity. Improved visibility and reduced avalanche danger will allow further observations later today, but we can report on a few natural avalanches. Hillman’s Highway and the Main Gully in Gulf of Slides ran full extent (R5 D3) of the path and into mature forest. Hillman’s “jumped the bank” near the approach trail and ran into the woods. Duchess also avalanched as did Gully 2 in Gulf of Slides and ran close to full path (R4 D2). We’re confident that other slide paths ran but thick summit fog is lingering this morning. The ice crust that has haunted us for weeks now is on the list of snowpack features to look for today. We’ll be checking it out for extent of exposure as well as faceting nearby.

The Sherburne Ski Trail benefited greatly from this week’s snowfall. Great coverage exists, though a bit of scouring may have exposed a rock or two in the usual wind hammered sections. 

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 Harvard Cabin.
• Posted 8:00 a.m., Saturday, March 17, 2018. A new advisory will be issued tomorrow.

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