Urban Avalanche Advisory

Current Advisory as of

January 21, 2022

Expires 7:00 AM the following morning.

Issued By Tom Mattice

Danger Level: 4 - High
View Danger Definitions

Today's Discussion

There remains a tremendous amount of uncertainty today around freezing levels and snow volumes.  The one thing you can surely count on is its going to be WET.  With precipitation totals over the next 2 days forecast to be from 5-8" on top of new snow over the last 24 hours at upper elevations avalanche danger is HIGH today.  Natural avalanches are likely and human triggered avalanches will be more than likely.

The question is what are you going to see and where are you going to see it.  With forecast temps to 40f at sea level and with current temps at 29 at Eaglecrest summit we have a mixed bag of conditions.  Many forecast models are saying we will see 34f and rains to 2500+' today and yet others keep us just a little cooler which would GREATLY add to snow volumes with the high precipitation volumes.

At upper elevations expect to see weakened wind slabs on N-W facing slopes.  Expect to see a storm slab that will grow rapidly and get weaker as we see increased warming today potentially to above freezing at all elevations.  If we see rain on snow to summit these storm slabs will rapidly weaken and the high precipitation rates will be adding increased stresses as well.  Tomorrow will be even warmer with continued rains continuing hazardous conditions.

Down low today expect to see possible loose wet and wet slab avalanches.  Your slab activity may be more limited and yet with 5-8" of rain on the snow today we could see base releases on rock faces, and if there are any previous weak layers this huge load will find them.  With potential for temps to climb above freezing at all elevations we may transition to Wet Slab and Loose Wet avalanches on all elevations and aspects.  Temperatures will be the driving force and yet the huge precipitation volumes will be making the snowpack feel the change rapidly.

Currently its 29f at Eaglecrest down from yesterday mornings 32f.  Mt Roberts is currently 32f down from 33f.  Still picking up snow.

Eaglecrest picked up 17cm of new snow from 21mm of SWE.  Still only 12 or so percent.  Not too wet yet.  Mt Roberts picked up 15cm of snow from 25mm(1") SWE.  Closer to 16% so a bit heavier and wetter with its temps right at freezing.

It wont take much warming to really change things today as we would transition from more snow up high to rains.  Yet currently from our weather stations to summit you can expect winterlike conditions to remain.     With temps right at freezing at our weather sites you can also assume you may have a little more new snow at uppermost elevations although this storm has been somewhat isothermal.

Winds remain the concern in the region for the new snow.  Much of the mountain will be pasted in or stripped and yet on lee slopes from N-W faces you may see weak wind slabs.  Sheep mountain saw winds to SSE89mph.  Eaglecrest peaked at SE73mph.  Mt Roberts also saw SE43mph winds.  Winds slabs will be your primary concern.

If temps stay cold enough today the snowfall rates would lead to storm slab activity eventually and yet it it warms much it will lead to more loose wet and potentially wet slab activity.   Definitely expect to also see some level of loose wet and wet slab activity at lower elevations in the region where we still have quite a bit of snow.

Today- Rain, heavy at times. Snow level 1200 feet. East winds 10 to 15 mph shifting to the southeast 15 to 25 mph. Gusts to 35 mph. Highs in the lower 40s.

Tonight- Rain, heavy at times. Near steady temperature in the upper 30s. Southeast winds 10 to 20 mph.

Saturday- Rain. Rain may be heavy at times. Highs in the lower 40s. Southeast winds 10 to 15 mph.

Please avoid the Flume Trail over the next 2 days and stay out of the gated areas above the Behrend's neighborhood.

 

Primary Avalanche Problem

Wind Slab

Problem Type:Wind Slab
Avalanche Size:Large
Avalanche Likelihood = Very Likely
Avalanche Trend = Increasing Danger

Description

Winds are strong around the region and will continue to blow today during a large snow/rainfall event.

We picked up 6-9" of new snow at our weather stations and potentially even a little more on summit during winds from 40-90mph around the region.

Many aspects may be stripped or pasted in and yet on slopes from N-W faces you may see increased wind loading and wind slabs will be likely.

Remember winds are also spatially variable and you may find loading in unusual locations.  Be cautious and recognize wind slabs will be your primary concern today at upper elevations especially for human triggered events.

With 5-8" precipitation over the next 2 days we could see natural activity and danger will be rising.  Temps may drive these to end up being wet slab events and yet for the time being cooler conditions remain.

Storm Slabs will also be possible with large precipitation volumes as long as conditions stay cool enough to remain snow.

Learn more about Wind Slab.

Secondary Avalanche Problem

Loose Wet

Problem Type:Loose Wet
Avalanche Size:Large
Avalanche Likelihood = Very Likely
Avalanche Trend = Increasing Danger

Description

We have great potential for both loose wet and wet slab avalanches today.  The loose wet being the more likely of the two.   With above freezing temps at sea level these events are possible to likely now as we see from 5-8" precipitation over the next 48 hours.

As we see warming today and again into tomorrow we will see rain on new snow at increasing elevations adding to the likelihood of these loose wet and wet slab events.  With 5-8" of SWE in the forecast expect to see wet avalanche activity at some time in the next 2 days.

Learn more about Loose Wet.

Today’s Avalanche Tip

Please continue to share your snowpack and avalanche observations with the Coastal Alaska Avalanche Center at CoastalAkAvalanche.org 

The more we know, the safer the snow.