Avalanche Advisory for Tuckerman and Huntington Ravines


 Posted: 8:24 a.m., Monday, December 31, 2007


 Tuckerman Ravine has HIGH, CONSIDERABLE, and MODERATE avalanche danger
 today. Hillman's Highway, Left Gully, the Headwall, the Bowl, the Lip,
 and Right Gully have High avalanche danger. Natural and human
 triggered avalanches are likely. TRAVEL IN AVALANCHE TERRAIN IS NOT
 RECOMMENDED. The Lower Snowfields have Considerable avalanche danger.


 Natural avalanches are possible and human triggered avalanches are
 probable. Be increasingly cautious in steeper terrain. The Little
 Headwall has Moderate avalanche danger. Natural avalanches are
 unlikely and human triggered avalanches are possible. Use caution in
 steep terrain.


 Huntington Ravine has HIGH avalanche danger today. Natural and human
 triggered avalanches are likely. TRAVEL IN AVALANCHE TERRAIN IS NOT
 RECOMMENDED.


 Yesterday afternoon we were able to get out and check out the snow in
 Tuckerman Ravine, and our field data showed variable conditions on
 different aspects. However, it's the new snow today and anticipated
 increases in wind speeds along with shifting directions that are the
 reasons for the High ratings today. Since snow began last night, the
 Summit has recorded 1.6" (4cm) of snow, while at our snowplot at the
 Harvard Cabin showed 3.9" (10cm) of 9.5% density snow. Snowfall should
 continue through the better part of the daylight hours, although only
 1-2" (2.5-5cm) additional accumulations are expected. Winds so far
 have been from the ESE and S and fairly light at 20mph (32kph).


 Looking at current conditions as I write, we're not yet into the High
 rating. As the low pressure system pulls away today, winds will shift
 around to the W and increase to 60-75mph (96-121kph) with higher
 gusts. These shifting and increasing winds will create significant new
 loading in both ravines. As a result, avalanche danger will rise
 throughout the day, in part from the additional snow that will fall
 earlier in the day, but more so due to the changes in winds. Traveling
 in avalanche terrain today is not recommended; however, if you make
 the decision to do so, pay close attention to what the winds are doing
 and how much snow is actually falling. Remember that with poor
 visibility it is easy to put yourself in the runout of avalanches
 without even knowing you are in avalanche terrain. This includes going
 up to the floor of either ravine to "check it out".


 Although today's concerns are focused on the new snow and winds,
 yesterday's field observations are worth mentioning. In Tuckerman
 Ravine, surface conditions varied widely. Under the Sluice, I watched
 Chris and Justin working hard to kick steps into a very hard crust one
 moment, and afterwards carefully tiptoeing across a large slab in
 Right Gully. Meanwhile, under the Chute and in the left Headwall, I
 booted up mostly medium-density slabs, but quickly found sheltered
 areas that were nowhere near as stable as what I was on just a few
 steps earlier (for you snowpit-diggers out there: CT5 Q1, ECTPN, and
 ECTPV were my quantifiable results). All of what we observed yesterday
 reinforces what we already knew--that the variability of the snowpack
 on Mt. Washington can be huge. On a day like today, it's easy to make
 the decision not to go into avalanche terrain. On days when you do
 decide to go, it's important to constantly assess the conditions
 underfoot, and never let your guard down.


 After this weather system moves away. Another one is on tap for
 Tuesday night. Even though it's New Year's Eve with parties
 everywhere, I would much rather have December continue as it has for
 the next few weeks.


 The John Sherburne Ski Trail is open with continuous snow from top to
 bottom. Expect good snow over a stiff base. THE LION HEAD WINTER ROUTE
 IS OPEN. This is a steep and challenging route for mountaineers.


 Crampons, an ice axe and the ability to properly use this equipment
 are recommended for safe travel on this route.


 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 or 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.


 Jeff Lane, Snow Ranger
 USDA Forest Service
 White Mountain National Forest