Avalanche warning issued as snow keeps falling in Southcentral
As of early Thursday morning, 30 inches of snow had fallen at the Turnagain Pass Snotel, a backcountry weather station, since the snow started flying Wednesday.
This heavy snow on top of an already poor snowpack will only make conditions worse in the coming days.
An avalanche warning remains in effect until 5 a.m. Friday March 15. The areas in the avalanche warning include Turnagain Pass, eastern Turnagain Arm, the Kenai Mountains, Western Chugach Mountains, Summit Lake and Seward.
Human-triggered and natural avalanches are likely on slopes greater than 30 degrees. Although not a part of the avalanche warning, recent snow in Hatcher Pass is also prone to slides.
Avalanches may run long distances, meaning areas below steep slopes are considered dangerous as they are potentially in an avalanche zone.
Avalanche conditions may exist outside the warning area. Backcountry users are urged to use extreme caution when venturing out into the fresh snow.
The first in a series of storms set to impact Southcentral came with powerful wind and significant snowfall. As of Thursday morning, some areas have already picked up close to 3 feet of snow with more on the way.
By Friday, many areas will receive more than 3 feet of snow from this first storm. A few areas are set to pick up more than 6 inches of liquid water equivalent in the form of snow.
This season has had an extremely varied and unstable snowpack. Inconsistencies in snow, whether that be light, fluffy dendrites or heavy, wet flakes, there was little consistency.
Most recently, a prolonged stretch of sunshine and mild temperatures melted a significant chunk of the snowpack and created a layer of surface hoar on top of the snow as new storms moved in.
The weak layer in the snowpack prompted high avalanche danger in the presence of new snow a week ago. Now, our most recent round of snow has added to the danger, but for a new reason.
Wind loading of recent snow increased instability on steep slopes. Snow that's blown as it falls will often be picked up and tumbled along the ground, turning the beautiful snowflakes into more round pellets that can pack more densely together.
The blowing snow is taken from the windward side of the mountain and deposited on the leeward side, sometimes at a rate of almost 10 times the snowfall itself. This puts more snow at higher elevations and the more dense layer on top: an avalanche-prone combination we witnessed unfold in our most recent storm.
More to Come
Over the course of the next few days, a parade of storms will continue to bring heavy snow to the mountains of Southcentral.
The line of storms will hit one after another for at least the next week, making it tempting for outdoor enthusiasts to get out and enjoy the fresh powder. However, varying temperatures, wind and an already unstable snowpack will keep the avalanche danger high.
Use extreme caution and conservative decision-making in any backcountry exploration in the coming week.
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