Posted 8:15a.m., Thursday, March 17, 2011
Tuckerman Ravine has Moderate and Low avalanche danger today. Hillman’s Highway, Left Gully, Chute, and the Center Bowl have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanches are possible. All other forecast areas in Tuckerman have Low avalanche danger. Natural and human-triggered avalanches are unlikely in these areas.
All forecast areas in Huntington Ravine have Low avalanche danger. Natural and human-triggered avalanches are unlikely. Watch for unstable snow in isolated terrain features.
Yesterday we expected to see 1-3” (3-8cm) of new snow but despite an honest attempt the skies just could not produce like we hoped. Snow began early in the morning but low-intensity flurries seemed to be the order of the day. Flakes fell for much of the day but the summit picked up a mere 0.5” (1.3cm) while lower elevations wrung out just a bit more. Our snow plots below the ravines were the big winners but that’s not saying much. Though both plots may have accumulated 2” (5cm), the warmth caused pronounced settlement. This morning nothing was left on our measurement board at Harvard Cabin thanks to temperatures maxing out at +2C and a crust encapsulated the new snow at Hermit Lake. Although we struggled to reach the forecasted snow accumulations at upper elevations the good news is that the summit was able to ward off the mixed precipitation and remain snow all the way through. We suspect the start zones received some mixed precipitation, as evidenced by a small pile of wet avalanche debris below Odell. Winds stayed out of the SW for most of the daylight hours before they pushed clockwise to the WNW. With an average daily speed of 40mph (65kph) the wind was successful in moving snow, and new windslab should be expected in N to ESE aspects. Light accumulations up high didn’t provide enough snow to make today’s ravine look significantly different than yesterday’s ravine, but I have no doubt that new instabilities have developed. This is most likely to be the case in the upper elevations of Hillman’s and Left Gully, as well as in some locations in the Chute and Center Bowl. These areas will be at the lower end of the Moderate rating, and warmth will aid in stabilization throughout the day. In Huntington, you may find small isolated pockets of unstable snow in several gullies, particularly Central.
A quick ridge of high pressure has just released the ravines from their cloudy shroud, however, it isn’t expected to last long. A warm front this afternoon will draw the clouds back in. As this happens we’ll see the chance of mixed precipitation return to our neighborhood. Winds will decrease a bit today from their current 65mph (105kph) and then ramp back up tonight with speeds in excess of 100mph (161kph). These conditions should have little effect on today’s stability but stay alert for changing conditions. If the forecasted mixed precipitation later today comes in as snow the avalanche danger will rise.
- 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.
- This advisory expires at midnight. A new advisory will be issued tomorrow.
Justin Preisendorfer, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856