Posted 9:00am, Thursday, March 3, 2011
Tuckerman Ravine has CONSIDERABLE, MODERATE and LOW avalanche danger today. Right Gully, Sluice, the Lip, and Center Bowl have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Lobster Claw, the Chute, Left Gully, Hillman’s Highway and the Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human triggered avalanches are possible. The Little Headwall has Low avalanche danger. Natural and human-triggered avalanches are unlikely.
Huntington Ravine has LOW avalanche danger today. Natural and human-triggered avalanches are unlikely. Watch for unstable snow on isolated terrain features.
The past 24 hours has been a dynamic reminder that predicting the natural world is a never ending challenge and we’ll likely never quite get it right 100% of the time. All weather forecasts by multiple meteorologists were calling for up to an inch of new snow yesterday afternoon with the approaching cold air mass that is now entrenched in the White Mountains. After a quick inch in the morning precipitation shut down until the afternoon hours when squalls generated rapid accumulation giving the Hermit Lake elevation about 6” (15cm) total for the day while the summit recorded 3.4” (8.6cm). Brian and I had a nagging feeling we would surpass the forecasted totals, but had no evidence to support this conclusion and we certainly didn’t expect a half a foot. Generally, humans’ understanding of weather is excellent and forecasts reflect that when looking at the big picture. However nailing exactly what will occur all the time is impossible so it will always be important to keep a close eye on what is actually happening and be able to change your plans quickly. Mountain weather can be quick changing and fickle. Although a substantial diversion from daily predictions is rare, it could happen on the day you’re in avalanche terrain. So albeit obvious, “Anticipate a changing avalanche danger when the actual weather differs from the higher summit forecast.”
Yesterday’s weather pushed the avalanche forecast to the limit and pushed a number of areas above their forecasted rating, particularly those at Low. West winds through the day between 60-70mph (96-112kph) loaded new snow into most forecast areas particularly those facing due East, namely Tuckerman’s Lip, Center Bowl, and Chute. Winds increased hitting 109mph (176kph) and shifted towards the NW during the overnight which scoured a number of locations. This is most true in Huntington where all gullies were heavily wind effected. As winds diminished, loading resumed early in the morning and is continuing as I write. Impressive plumes of snow are evident over Hillman’s, Left Gully, and the Right Gully/Sluice area. Therefore conditions are still changing and we can’t rule out the potential for natural avalanche activity in some areas. The areas we are most focused on in this regard are the Center Bowl through Right Gully which we have posted at Considerable. The areas posted at Moderate that are going through the most change are the top climber’s left of the Lobster Claw, and top right of Left Gully as well as Hillman’s. New loading in these locales are bringing in additional slab, but natural avalanches being “unlikely” is still most appropriate hence their Moderate rating. Getting to the bulls eye points:
- Yesterday’s snow and continued high winds from the NW will bring in some additional loading today creating new slab and some added instabilities.
- Very cold air climbing from -23F towards -5F today will keep new slabs snappy and reactive to triggers offering good propagation in softer slabs that were not beaten by extreme winds over night.
- The most suspect slabs will be in the strong lee of W and NW winds so be increasingly cautious approaching new deposition near rock buttresses and terrain formations that shielded snow surfaces from high winds. These slabs will likely be softer and more unstable than a number of very hard slabs out in the open.
- 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.
Christopher Joosen, Snow Ranger
USDA Forest Service
White Mountain National Forest
(603) 466-2713 TTY (603) 466-2856