|Posted: 8:15a.m., Friday, December 10, 2010
This is an early season GENERAL AVALANCHE ADVISORY. Use of the 5-scale danger rating system will begin when conditions warrant. A General Advisory is issued when instabilities are isolated within the entire forecast area. However, it is important to realize that avalanche activity may occur before the issuance of a 5-scale forecast. Under a General Advisory you need to make your own snow stability assessments when venturing into avalanche terrain.
Winter seems to have settled into the White Mountain region, even if it has been somewhat reluctant to develop a consistent pattern. While north and west of the Presidential Range got over a foot of new snow on the 6th, there isn’t a single snow grain on the ground in Conway. You might expect Mount Washington to have gotten the heavier end of that spectrum, but you’d be wrong. In fact, the summit has measured only 8.7” so far in the entire month of December. What this means for avalanche potential is that snowfields remain relatively small, but they are slowly and steadily growing in size and distribution. As they grow, so does the size of the bed surfaces for future instabilities. Early season is a time characterized by a high degree of spatial variability, so as you move around the ravines you should continually be assessing the snowpack as you go.
The weather pattern for the next couple days looks to include continued cold weather, a chance of snow showers, and a moderate W and SW flow that may move new snow into the ravines. Into Sunday and Monday some weather will be developing and we’re crossing our fingers that it stays frozen before hitting the ground. Remember that conditions change quickly this time of year; don’t expect things to look entirely the same this weekend as they did last weekend.
Be aware that a small avalanche can be very dangerous if it is triggered in the wrong spot. Snow that has been deposited over blue ice often is very poorly bonded at the interface. Ice climbers should consider this ahead of time and place protection before crossing suspect slopes. We are now in early winter in the high mountains so remember that hiking trails going through steep terrain will require mountaineering equipment and skills.
Don’t wait any longer to refresh your avalanche skills. Practice with your beacon, review your safe travel rules and snow stability tests, and sign up for an avalanche course. We now have all the avalanche course providers in the valley this winter on our website, www.mountwashingtonavalanchecenter.org.
Jeff Lane, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856