The National Weather Service has issued a WINTER STORM WARNING for Portage Valley, Eastern Turnagain Arm and Turnagain Pass.
Blizzard conditions are expected today along roadways from Girdwood to Seward. This should be one of the first Red Flags noted for a day in the backcountry. Snowfall should begin this morning and pick up in earnest overnight. Although only 4-6″ is expected to accumulate through the daylight hours, ridgetop winds are already cranking up (30mph with gusts to 60mph from the east). Another Red Flag. An additional 10-14″ of snow is expected from 6pm tonight to 6am tomorrow morning. Visibility will be hampered as usual when it’s stormy and all this said, knowing where avalanche terrain is and isn’t will be key for today.
Avalanche activity will be in the form of fresh wind slabs, cornice falls, new storm slabs and sluffs in the new snow. Wind slab avalanches are forming now as there is plenty of loose snow available for transport. Any fresh wind slab found should be easy for a human to trigger. Storm slabs will be an issue once snowfall rates increase, which could be later today. If heading out into the backcountry, pay close attention to fresh wind slabs forming and new snow amounts. Winds could make it down into the trees today, so look for shooting cracks and slabs in areas that may not be common to have them.
If choosing to avoid all these developing avalanche issues, avoid avalanche terrain or head to your local ski area!
Glide avalanches are a real concern as these have been releasing over the past week. The most recent release of a glide crack was noted yesterday on Lipps – photos below. Corn Biscuit also had a recent release. Once skies clear (possibly tomorrow), pay close attention to cracks and limit as much time under them as possible – they are moving!
Photo of Lipps avalanche on left, taken from the Johnson Pass turn off by Dan Beutel. Close of same avalanche taken by Andy Moderow from Pete’s North ridge.
Glide crack on SW aspect of Magnum opened after ski tracks were layed down last week – just to the east of PMS Bowl (photo: Andy Moderow)
Lynx creek clide new cracks and old avalanche release – these look prime to release and anytime (photo Andy Moderow)
South of Turnagain: As we have been mentioning for some time, a shallow and poor snowpack structure exists in the Summit Lake zone. Buried weak layers of facets associated with crusts sit 1-3′ below the surface near the base of the snowpack. It will be interesting to see if this series of storms overloads them and large avalanches breaking near the ground result.
Yesterday: Mostly cloudy to obscured skies with patchy valley fog. Light precipitation over the past 24-hours only added an inch of snow to Girdwood Valley and a trace at Turnagain. Ridgetop winds were light and variable until ramping up to the 20-30mph range at 0200 this morning with gusts to 50mph from the NE. This is due to the next system moving in currently. Temperatures cooled yesterday to the teens along ridgetops and 25F at 1,000′ yet have climbed back up early this morning to 20’F along ridgelines and 30F at 1,000.
Today: The first in a series of warmer storms will hit today. Snowfall should begin this morning with 4-6″ accumulating today. Snowfall rates look to increase tonight with another 10-14″ expected by tomorrow morning. The rain/snow will start at sea level and increase steadily to 1,000-1,500′ overnight. Ridgetop winds will be in the 30-50mph range with gusts to 80-90mph. Temperatures will rise to near 32F at 1,000′ this evening and to the upper 20’s along ridgelines.
Tomorrow: A quick break in weather is expected Monday before another system hits Monday night into Tuesday. Although a break in precipitation and cloud cover may occur Monday, ridgetop winds at this point look to remain strong.
*Seattle Ridge weather station was heavily rimed and the anemometer (wind sensor) was destroyed.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||25||trace||0||53|
|Summit Lake (1400′)||21||0||0||12|
|Alyeska Mid (1700′)||26||1||0.1||36|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||23||*N/A||*N/A||*N/A|