Good morning. This is Wendy Wagner with the Chugach National Forest Avalanche Information Center on Monday, December 26th at 7am. This will serve as a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).
There is a MODERATE avalanche danger today for wind slab and soft slab avalanches. Recent winds have loaded leeward slopes and the sides of gullies at the mid and upper elevations. Human triggered avalanches are possible today in these wind drifted areas, primarily in steep terrain. Areas out of the wind may see some minor sluffing in the loose snow and shallow soft slabs.
The easterly winds yesterday were strong enough to form plumes off the peaks and blow the several inches of low density snow into sensitive wind drifts and slabs. Shooting cracks were observed but only a few small wind pockets were triggered. Shallow sluffs in the new snow were seen on steep slopes, including east facing Seattle Ridge. One soft slab was reported as well. Details HERE.
Two processes are keeping wind slab avalanches the primary concern today. First, winds picked up again overnight averaging 15mph and gusting to 30mph. These are not large numbers; however, 15mph is strong enough to transport new snow into sensitive drifts. Second, cold snow generally does not bond as quickly as ‘warmer’ snow (snow in a mid-20’s environment for instance). The fresh drifts yesterday are likely still not well bonded to the underlying new/old snow today. These will most likely be found just off ridge lines, on convex rollovers and sides of gullies.
The second concern will be soft slabs forming in the loose, minimally wind affected, snow due to an increase in air temperature today. Temperatures look to rise around 10deg F which may cause the loose snow to become more cohesive and begin to act as a slab. These soft slabs will likely be shallow and in the mid to lower elevations.
A good clue today for both wind and soft slab issues will be to watch for any cracking, or shooting cracks, in the snow around you. This is a sign the snow could slide if the slope is steep enough.
Partly cloudy to sunny skies and chilly temperatures greeted many folks yesterday. Turnagain Pass picked up 3-6” of light snow early yesterday and Girdwood Valley around 8”. The winds increased from the east, averaging around 20mph and gusting to 35mph at the Sunburst weather station. Overnight, the winds picked up again and are blowing near 15mph with 30mph gusts. There may be a fresh inch or two around Turnagain Pass this morning. Temperatures are slowly climbing out from the single digits at the upper and lower elevations.
Today, expect mostly cloudy skies and intermittent snow showers as the low pressure system in the Gulf spills into our area. Temperatures should rise into the teens at most locations with a chance for an inch or two of snow through the day. Winds are forecast to taper off and blow around 10mph with 25mph gusts from the northeast.
CNFAIC Weather Page and the NWS forecast
Graham will issue the next advisory Tuesday morning. If you get out in the backcountry we want to know what you are seeing. Please send us your observations using the button at the top of this page or give us a call at 754-2369. Thanks and have a great day.