This advisory expires at midnight.
Tuckerman Ravine has Moderate and Low avalanche danger. The Sluice, Lip, Center Bowl, Chute, and Hillman’s Highway have Moderate danger. Natural avalanches are unlikely and human triggered avalanches are possible. All other forecast areas have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.
Huntington Ravine has Moderate and Low avalanche danger. 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 gullies have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.
AVALANCHE PROBLEMS: Human triggered Wind Slabs and Persistent Slabs are the main concern today. Cold weather is still dramatically slowing slab problems from stabilizing. Continue to expect an intense amount of spatial variability. Some areas of slab have been sitting for about a week and are clearly persistent. With clear cold conditions in place we will be looking for facet development in these older slabs today. Wind slabs from more recent snow on Monday haven’t changed too much due to cold air slowing consolidation and sintering. These will likely lump into the Persistent Slab category by tomorrow depending on what we find today.
WEATHER: Temperatures continue to be very cold and are the discussion point of choice. At higher elevations, mercury will dance around -10F (-23C) and then drop to about -20F (-29C) tonight. Winds will shift from NW to W this morning, and build to 45-50mph (72-80kph) late this afternoon. These velocities are far from what the mountain can deliver, but coupled with sub-zero air, they should be respected. Skies will move from clear to overcast later. Weather models looking out towards the weekend are making me nervous. Although temperatures may rebound a bit on Saturday, flirting as high as a balmy zero, that will change. Our gauges may fall lower than they have yet this year on Saturday night and Sunday morning with winds in excess of hurricane force. Start watching the weather closely if you are planning a weekend trip.
SNOWPACK: There is a lot of spatial variability in areas both rated at Low and Moderate. You will find icy old surfaces from the last rain event with nearby dry slabs, knee deep or more, all within 30 meters or less of one another. This situation is common for us due to our high winds and their scouring effect. Be on the lookout for weaknesses from new snow buried at different depths, depending on location, from precipitation that fell on Sunday and Monday. Snow initially loaded on light W winds before speeds increased to create denser slabs. These stronger layers, stacked on lighter weaker ones, is the main wind slab avalanche problem in areas posted “Moderate”. Also examine older deeper slabs for facet development that we are calling persistent.
- 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 800a.m. 1-23-2014. A new advisory will be issued tomorrow.
Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856