Bollettino valanghe

Presidential Range

Mount Washington Avalanche Center
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Pericolo valanghe

Sat
Alta quota
1 · Debole
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

A dust-on-crust scenario plays out today as very light snow showers bring an inch or two of snow on light south winds. In steep terrain, the icy and mostly impenetrable crust is the predominant surface on wind exposed avalanche paths. New snow falling last night and today may create small, loose dry avalanches in the steepest terrain. Small, reactive wind slabs are unlikely but not impossible in steep terrain where wind blown snow accumulates. LOW avalanche danger exists except in these isolated areas of extreme terrain. 

The potential for a long sliding fall on the icy surface tops the list of hazards today. If venturing into steep terrain, bring an ice axe and crampons (not just microspikes), and consider roping up earlier than you ordinarily would on lower angled terrain. The odds of successfully arresting a fall with an ice axe is diminished in these hard, icy conditions.

The Winter Lion Head Route is the most direct route to climb to the summit from Pinkham Notch. The Tuckerman Ravine Trail through the Bowl, and the Lion Head Summer Trail are much more exposed and pass through avalanche terrain.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1

    Light density snow remains in the forecast today though so far snowfall totals have remained on the low side of what was forecast. New snowfall and wind direction are the bullseye data points to look for today and tomorrow. If we exceed the forecast snow total or if the wind shifts early then we will exceed our current danger rating as triggerable slabs develop. The icy, freezing rain crust which developed earlier in the week has made ski conditions miserable for all but the most dedicated (i.e., masochistic) skiers and riders. The temptation may be to seek out the newer snow, which may be unstable slabs, in order to avoid the icy crust. A safer plan is to wait for the new snow today and tomorrow to blow into the terrain then settle and bond to the surface beneath. This would result in better, smoother skiing conditions to boot.

    Pockets of older, stiff snow packed in by 100 mph west winds on Wednesday currently exist in sheltered areas but not enough of it is around to allow for travel on foot without crampons. 

Avalanche Discussion

Traveling in the mountains today will be challenging due to a breakable crust in lower elevation or wind sheltered areas and a dense, hard, icy surface in steeper areas more exposed to the wind. Pockets of older, stiff snow packed in by 100 mph west winds on Wednesday currently exist in sheltered areas but not enough of it is around to allow for travel on foot without crampons. Microspikes on lower angled slopes and trails will be useful, with ice axes and crampons needed for anything steeper. Waiting for the new snow today and tomorrow to blow into the terrain then settle and bond to the surface beneath would be a safer plan with better skiing conditions to boot. The old adage to “ski the conditions, not your calendar” is as useful in periods of low avalanche danger as during elevated danger.

We just passed through one of the more active periods of snow and avalanche problems that we’ve had for some time, in part due to the absence of a typical January thaw that resets the snowpack. Unfortunately, the freezing rain and warm temperatures on Tuesday locked up the upper snowpack and spoiled everyone's powdery fun on skis in the backcountry. If you shift gears to ice climbing or mountaineering, keep this crust on your radar. It is an unforgiving surface that kills many more people in our range than avalanches. What would ordinarily be a harmless fall on stiff snow on a 30 degree slope can turn fatal in these icy conditions where self-arrest techniques simply do not work. Rope-up early and have your gear and technique completely dialed before venturing into the alpine. 

You may have noticed that the persistent slab avalanche problem is gone from the avalanche problems. This doesn’t mean that you won’t find faceted snow anymore. In fact, to the contrary, the new ice crust is likely to cause continued temperature and vapor pressure gradients that drive even more faceting. But without a snow load on top, there is no real avalanche problem so it’s off the list. Near crust faceting may be something to look at in the near future but the primary problem will likely be new snow blown into wind slabs which struggle to bond with the freezing rain crust. Our most recent bed surface and weak layer in our largest avalanche paths at middle and upper elevations ran on the smooth, wind-packed layer built by the wind event on January 24th that reached 157 mph on the summit of Washington. Perhaps the recent thaw and subsequent refreeze will change that.

More avalanche deaths occured yesterday in the western US. Information on all US avalanche fatalities can be found here with details and accident reports appearing as they are submitted to the CAIC.  An interview with Simon Trautman of the National Avalanche Center on the recent cluster of fatal avalanche accidents can be found here

 

Thanks to everyone for taking the time to submit all the observations of snow and avalanche conditions, both inside and outside our avalanche forecast area. Please keep them coming. 

 Your avalanche, snowpack, or weather observations are extremely valuable to the forecasters at MWAC. Help create a more accurate avalanche forecast by submitting your observations here

Listen to the weekly MWAC Outreach Podcast provided by Ski The Whites. Discussions include snowpack information, weekend outlook, and general avalanche related info. 

Thursday, February 25 @ 7PM - Barriers to Cognition and Perception with Blake Keogh  - A Free Zoom Webinar.

The Harvard Cabin is open for camping only with no entry allowed inside the cabin. There is no access to the breezeway at HoJos.

Please Remember:

  • Safe travel in avalanche terrain requires training and experience. This forecast 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.
  • Avalanche danger may change when actual weather differs from the higher summits forecast.

For more information contact the US Forest Service Snow Rangers, AMC visitor services staff at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or seasonally at the Harvard Cabin (generally December 1 through March 31). The Mount Washington Ski Patrol is also available on spring weekends.

Regioni coperte