| Posted: 7:50 a.m., Sunday, March 2, 2008 |
Today's ratings remain the same as yesterday as this avalanche cycle continues to play out. Yesterday's storm deposited 9.5" (24 cm) of new snow on the summit of Mt. Washington with a density of 9.7%. At Hermit Lake we recorded 13" (33 cm) of snow with an average density of 8.2%, with the lightest snow falling early and becoming denser through the day. This upside down snow pack did result in avalanche activity yesterday but the real show didn't begin until the winds shifted to the WNW and increased. This occurred later than forecasted resulting in some very calm conditions on the mountain yesterday as the low pressure system passed by. Around 4:00 pm they began to accelerate steadily and are now hedging toward the NW at speeds in the 70 mph range (112 kph). These winds are forecasted to continue increasing through the morning to 90 mph (145 kph) and then back off to 60 to 80 mph (96 to 129 kph) for the midday hours. These winds are finding plenty of snow above treeline to transport into the Ravines. We have the new snow discussed above as well as some from last week's storm that measured around 9" (23 cm). That snow hasn't seen winds this strong since it fell. What this all boils down to is wind loading has been occurring since yesterday afternoon and will continue to occur throughout the day. The increasing winds create increasing slab densities and these slabs have been sliding and will continue to avalanche today. Furthermore, I think that conditions are such that we could see some paths run farther than they have this season. We have also been discussing how we are seeing avalanche activity occur in places that we don't usually see it happen. Chris just observed some fracture lines on the way into Huntington Ravine this morning in gullies that have filled in to the climber's left of the Escape Hatch. Poor visibility will preclude you from seeing what is avalanche terrain today. Realize that avalanches are happening and there is more avalanche terrain on the mountain than usual. Be conservative in your travel decisions today.
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 it’s 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.
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Avalanche Advisory Archives.
United States Avalanche Danger Descriptions.
Échelle Canadienne de risque d’avalanche.
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