Avalanche Advisory for Tuckerman and Huntington Ravines


 Posted: 8:35 a.m., Monday, March 3, 2008
 Tuckerman Ravine has Low and Moderate avalanche danger today. Hillman's
 Highway has Low avalanche danger. Natural avalanches are very unlikely
 and human triggered avalanches are unlikely except in isolated pockets.


 Normal caution is advised. All other forecast areas in Tuckerman Ravine
 have Moderate avalanche danger. Natural avalanches are unlikely and
 human triggered avalanches are possible. Unstable slabs are possible in
 steep terrain. Use caution in steeper terrain.


 Huntington Ravine has Low avalanche danger today. Natural avalanches
 are very unlikely and human triggered avalanches are unlikely except in
 isolated pockets. Normal caution is advised.


 We have gone from Extreme avalanche danger to Moderate and Low as a
 result of widespread avalanche activity and wind scouring. Yesterday
 provided us with quite a show. Visibility was in and out and we were
 able to observe new fracture lines come and go through the day. Just
 about everything that is considered avalanche terrain (i.e. any angled
 snow slope) avalanched yesterday. Aside from the usual suspects, we had
 multiple avalanches in Raymond's Cataract, along the Lion Head Ridge,
 in all the small gullies climber's left of the Escape Hatch and in
 small snowfields around the Tuckerman Ravine area. As far as our
 forecasted areas go, they all slid too. At this time it looks like the
 Bowl will win the contest for the largest avalanche of this cycle. I
 haven't had a chance to look at the debris, which is likely wind
 scoured, but we saw a large fracture line across the Headwall and into
 the Sluice yesterday. Due to the depth and length of the fracture line,
 I don't think out other paths can compete. As winds increased
 yesterday, they began to scour some areas and move a lot of new snow to
 areas lower on the mountain. The most recent avalanches occurred in the
 Lower Snowfields near the Little Headwall and in pockets lower down in
 Huntington Ravine. The cumulative effect of winds and avalanches leaves
 us with today's mix of Low and Moderate conditions.


 In Huntington Ravine, the wind created hard windpack or scoured the
 surface down to a crust layer. That doesn't mean there are not isolated
 pockets to be concerned about. Good route finding skills will allow you
 to avoid these. In Tuckerman, there is quite a bit of wind slab that
 came in after the most recent round of avalanche activity. Fracture
 lines in the Bowl are muted as a result of wind loading. The south side
 of Tuckerman including Left Gully is not as much of a concern as the
 north side including the Headwall, Lip, Sluice and Right Gully. These
 areas represent the upper end of the Moderate rating due to the
 possibility of people triggering avalanches. If you choose to explore
 the Little Headwall area or the Lower Snowfields expect to find some
 unstable slabs there as well. As mentioned, areas lower on the mountain
 picked up a lot of new snow yesterday and our most recent slides were
 at these elevations.


 There is a chance of mixed precipitation or rain showers for the
 mountains today but there isn't much moisture expected. Winds are going
 to increase this afternoon and into tonight reaching 100 mph (161 kph)
 overnight. These winds could start the snow guns again and new loading
 may occur. This will be something for you to keep an eye on today. The
 winds will be out of the west and may find some nooks and crannies that
 have snow that yesterday's northwest winds couldn't find. The weather
 for the rest of the week is complicated. Mixed precipitation and snow
 are expected overnight and into tomorrow morning. Then a complex system
 arrives Tuesday night and into Wednesday. This has the potential to
 drop over 1" (2.54 cm) of liquid but we don't really know what form it
 will come in. Snow, sleet, freezing rain and rain are all possibilities
 right now. The active weather pattern continues after that one with
 something brewing for Friday. It certainly hasn't been a boring winter!


 The Lion Head Winter Route is not one of our forecast areas but does
 have potential to produce avalanches as anchors become covered and the
 snowfields increase in size. We are currently at that point so its
 important to make your own avalanche stability assessments and use safe
 travel techniques when following this route. Straying from the marked
 path quickly puts you into more significant avalanche terrain. The Lion
 Head Winter Route was designed to mitigate avalanche risk as much as
 possible, but does not eliminate it. It usually offers the safest
 direct line up the east side of Mt. Washington. If you plan on being in
 steep terrain, make sure you have crampons, an ice axe and the ability
 to self arrest. This includes the Lion Head Winter Route. The Sherburne
 Ski Trail is open with new snow, a lot of wind drifts and good
 coverage.


 Please Remember:
 o It is impossible to accurately predict natural events, such as
 avalanches, in every instance. This Advisory is one tool to help you
 make your own decisions in avalanche terrain. It should be used along
 with safe travel techniques, snow stability assessments, an
 understanding of weather's effect on the snowpack, and proficiency in
 avalanche rescue.


 o You should obtain the latest weather forecast before heading into
 the mountains. Anticipate a changing avalanche danger when actual
 weather differs from the National Weather Service forecast.


 o For more information, contact the U.S. Forest Service Snow
 Rangers, the AMC at Pinkham Notch Visitor Center or Hermit Lake
 Shelters, or the HMC caretaker at the Harvard Cabin. This advisory will
 expire at midnight.


 Brian Johnston, Snow Ranger
 USDA Forest Service
 White Mountain National Forest