Posted 8:40 a.m., Thursday April 7, 2011
Tuckerman Ravine has MODERATE and LOW avalanche danger. The Lobster Claw, Right Gully, the Sluice, Lip, Center Bowl, and the Chute have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. Heightened avalanche conditions exist in specific terrain features. Evaluate snow and terrain carefully to identify areas of concern. Left Gully, Hillman’s Highway, 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 LOW avalanche danger. Natural and human triggered avalanches are unlikely except in isolated terrain features.
Finally a stunning morning on the mountain! It doesn’t seem that we have been treated to a lot of these this winter which makes them all the more inspiring when they arrive. With the high pressure settling in overhead it should be quite a nice next 48 hours before things slowly change over again the second half of the weekend. It will be a blue bird day today, but don’t shut off your keen avalanche awareness detectors because we have some fresh cold slabs to be aware of this morning. Over the past 36-48 hours (Tuesday night into yesterday morning) the Summit received 3.5” (8.75cm) of cold snow on high winds. Brian and I found about 3” (7.5cm) around the cabins by 7am Wednesday after the summit had only recorded about half that amount. Based on these morning observations, periods of S1 and S2 (1-2cm an hour) snowfall intensity rates between 7 and 9 o’clock, and some afternoon snow, we believe avalanche terrain likely saw just a bit more snow than the summit recordings. This snow was associated with average winds between 40-60mph (65-97kph) from the W and NW with temperatures climbing up out of the low single digits F, ideal conditions to move new soft slab into some E facing aspects.
What we are seeing this morning is a classic yin and yang between the two Ravines. Huntington has solid Low avalanche conditions with pockets of new snow in Central Gully and high in the northern side of the Fan. Over in Tuckerman, Hillman’s Highway and Left Gully have some limited new snow that should be watched, but generally they have been scoured down to old surface. This changes rapidly as you move from the Chute over towards the Sluice. Old hard surfaces exist under the Chute and down low under the climbers left half of the Center Bowl. Up high above the narrows in the Chute, across the steepest parts of the Headwall in the Center Bowl, and particularly in the Lip and Sluice new cold soft slab conditions exist. The Lip and Sluice are the areas of most concern this morning and I consider them in the upper half of the Moderate rating due to their avalanche potential in reaction to a human trigger. Through the morning hours they will retain their cold snappy nature which should subside a bit later this afternoon. Although clear sunny conditions with dropping winds will allow directly south facing slopes to pick up some solar gain, helping them start to stabilize, this won’t be as true for SE and E facing aspects. Therefore the Lobster Claw, Right Gully, and portions of the Sluice will likely see some stabilizing later today, but I would remain suspicious of the Lip and the climbers left side of the Sluice closest to the Lip due to their SE and E nature.
The Harvard Cabin is now closed for the season. Camping in the Cutler River Drainage is only allowed at Hermit Lake Shelters.
- 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 caretaker at Hermit Lake Shelters.
- This advisory expires at midnight. 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