Observations

Mount Webster

March 5, 2021 at 12:00 PM
Name: Ryan Lewthwaite| MWAC
Location: Mount Webster

On a drive over Crawford Notch an older avalanche was noticed on the southwest aspect of Mount Webster. This avalanche may have occurred on Monday when the area received a period of wetting rain, but I am uncertain. The avalanche was small relative to the path, but could have buried, injured or killed a person if they were entrained. The location of the avalanche is adjacent to the AT where it crosses Hwy 302 and is visible from the roadway. At an elevation of ~2100 feet the snowpack here is very shallow and has been affected by sun, rain, and is exposed to prevailing winds. The avalanche stepped down and slid on an old snow and ice/rock bed-surface that has water running over it. The lubricating effects of water underneath a snowpack can help pull it from the slope which was at most 35 degrees in steepness. Old facetted snow grains that comprise the bottom half of the snowpack were a catalyst in the failure. The debris was not visible from my perspective and I did not explore the crown. This avalanche would be categorized as a soft slab with an unknown mechanism of trigger at or near the ground and within old snow SS-U-R2-D2-G/O. The area was roughly 100 x 150 feet with a maximum crown height of 20 inches.