Turnagain Pass

A quick moving storm is impacting most areas in Southcentral Alaska this morning. Anywhere from 6-16″ of new snow is possible depending on what areas in the Girdwood/Portage/Turnagain Pass regions are favored. Gale force Easterly winds on the other hand are equally impacting the ridgetops across the regions; Sunburst weather station is averaging in the 60’s mph with gusts in the 90’s. Precipitation began last night and as of 6am this morning, storm totals are:

Girdwood Valley –  1.1″ of water at Alyeska’s Top station (2800′) = ~10+” of snow 
Turnagain Pass –  0.2″ of water (1880′) = 3-4″ of snow in the Alpine
Summit Lake –  0″ 

Another 5-7″ of snow is expected today on top of the totals above at the higher elevations. Along with a storm day comes your garden variety storm snow issues, listed below. These issues are dependent upon the amount of new snow that falls. Turnagain Pass seems to be on the losing end so far but may see a bump in precip later this morning. Bonding with the old snow surface is expected to be initially poor, especially on South, West and East aspects due to a slick and hard pre-existing sun crust.

WIND and STORM SLABS:
With such strong winds, most slabs formed today will have a wind component, even in the lower elevations. Wind slabs could build as thick as 2+’ in higher snowfall zones but will likely be around 8-12″ in the Turnagain Pass area. Watching for current wind loading and cracking in the snow around you, as well as performing quick hand pits and using a pole to feel for stiff snow over softer snow, are all good ways to suss out slabs.

LOOSE SNOW AVALANCHES:
Sluffs should be expected in areas out of the wind. These are likely to run fast and far on aspects with a crust underneath. Additionally, damp or wet snow sluffs, within the new snow, will trigger easily with the first warming by the sun (possibly late today or tomorrow).

CORNICES:
Cornices will increase in size with this storm and may fail naturally triggering an avalanche below – similar to last week.

North facing aspects above 2,000′ have a variety of weak faceted layers 2-3′ below the surface. For the most part these have adjusted to the current load, however with additional load today (new snow and wind) they have the potential to re-activate. This means either a storm snow avalanche could ‘step-down’ and trigger and deeper slide lower on the slope, or a slab could fail initially in these old weak layers. Either way, Northerlies harbor potential for large slab avalanches.

If you find yourself hunting for fresh snow after this storm, be aware that a slab avalanche breaking in old snow 2-3+’ down is possible on steep North facing terrain.