Tuckerman Ravine has CONSIDERABLE, MODERATE, and LOW avalanche danger. The Lip, Center Bowl and Chute have Considerable avalanche danger. Natural avalanches are possible and human triggered avalanches are likely. Right Gully, the Sluice, Left Gully, and Hillman’s Highway have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The Lobster Claw, the Lower Snowfields, and the Little Headwall have Low avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.
Huntington Ravine has MODERATE avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible.
The mountain picked up a few inches of snow yesterday with up to another couple forecasted today. We anticipate some brief shots of high intensity squalls this morning before getting into a clearing trend later in the afternoon. SW and W winds between 40-60 mph (65-96kph) overnight were perfect loading speeds for our east facing Ravines. These W winds will increase in velocity to 60-80mph (96-129kph) before retreating to 50-70 (80-112kph) later. This all translates into an increasing avalanche danger that began yesterday and should peak at the tail end of today’s regional snow squalls. The areas of most concern are the largest E facing slopes of Tuckerman’s Center Bowl. As you move away from the center towards the Chute and the Sluice you will likely find more variability with both old icy surfaces and freshly deposited slabs. In Huntington you should find a tremendous amount of spatial variability within each gully. The recent thaw turned several gullies into shoe string ribbons going up the Ravine. Therefore, it won’t take a lot of snow to generate pockets that are wall to wall in multiple pinch points that will be difficult to avoid. So prepare to be on hard icy surfaces one minute and into new slab the next. Expect all snow that is not the old concrete from the recent warm up to be harboring weak layers and varying degrees of instability. Also anticipate bonding at the interface between the icy surfaces and the new low density slabs to be poor. With increasing winds and more snow today I would also be ready for new crystals to become beat up and fragmented packing into denser slabs over pockets of unconsolidated snow that were deposited yesterday. Due to the slick nature of the old bed surfaces you can expect frequent spindrift sluffing again today perhaps build into slabs on mid-slope benches such as in Odell, Pinnacle and Central. Because of all this you will probably find some slopes on the upper end of the Moderate rating in several locales in the Huntington gullies.
In addition to the hazard of avalanches also keep in mind the potential for long sliding falls on the hard slick surfaces found in many locations. As mentioned yesterday, if you fall anywhere expect to gain speed quickly and hit earthly objects because clear run-outs just don’t exist. Also be ready for an arctic blast of very cold air bringing the mercury down to -10 F (-23C) today and -20 F (-29C) tonight. Climbing in these conditions is rugged and where one small issue can snowball into something much worse. Although this isn’t a recommendation for soloing I am personally quite wary of doing anything roped in these temperatures, because no matter how fast you are “roped = slow” for most of us. A slight temperature reprieve for the first half of the holiday weekend should occur before diving back into very cold air Sunday night for several days.
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 8:23a.m. 1-17-2013. 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