Avalanche Advisory for Saturday, February 25, 2017 at 7 am- Update, Sunday 2/26 at 10am

Issued: Sat, Feb 25, 2017 at 7AM

Expires: Sun, Feb 26, 2017

Update 2/26

Please check OBSERVATIONS before heading out into the backcountry. Winds were stronger than recorded at weather stations and Marmot Wx station has been in and out with wind data. Two human triggered slab avalanches occurred on Saturday 2/25 on 4068′ and Hatch Peak. If you observed or triggered an avalanche this weekend, please consider submitting an observation. 

 

Join the Alaska Avalanche School and the Hatcher Pass Avalanche Center for a FREE Avalanche Awareness Class at Backcountry Bike and Ski in Palmer, TONIGHT,    Feb 25th 6-8pm.  Just show up!

Above 3,500ft Considerable

2,500 to 3,500ft Considerable

Below 2,500ft Low

Degrees of Avalanche Danger ?

1. Low
2. Moderate
3. Considerable
4. High
5. Extreme

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

AVALANCHE PROBLEM: LOOSE SNOW

The avalanche hazard is CONSIDERABLE today for loose-dry sluffs in steeper terrain.

A significant amount of new snow accumulated at HP this week! Fortunately, the new snow has remained untainted by the matanuska winds and valley rain.  Expect 20-24″ or more of new, low density snow to be capable of producing sluff on slopes 40º and steeper, on all aspects, and at mid and upper elevations.  Sluffs will be within the storm snow as well as capable of sluffing down to the old near surface facets sitting on a knife hard persistent slab. This could increase speed and distance of travel. These sluffs will have the ability to carry you off your feet, or over cliffs, and possibly bury a person in a terrain trap.   Sluff  management skills will be necessary in steep terrain.

An increase in wind speed could easily transport large amounts of low density, new snow, into slabs, and quickly increase the avalanche hazard.

Lots of powder havens comprised of safer low angled terrain exist for today’s riding and skiing pleasure.

 

 

AVALANCHE PROBLEM: PERSISTENT SLAB

The avalanche hazard is MODERATE today for persistent slabs at mid to upper elevations on all aspects.

As visions of snow fairies and powder shots cloud your judgement, don’t forget our foe, the persistent slab. The persistent slab problem still lingers at the bottom of the snowpack.

Triggering a persistent hard slab, 2-6 feet deep, is a low probability/high consequence risk. It is possible, but not likely. Assessing this hazard will be difficult. The continuity of the slab is highly variable and increasingly stubborn, which may allow for many people to travel on a slope before finding a trigger point. With this kind of hazard, reduce your vulnerability, and increase your safety margins by using safe travel protocol.

Always travel one at a time between safe zones in avalanche terrain, use spotters, and have everyone in your group carrying beacons, probes, shovels, and ideally airbags.  Know how to use, and be practiced with these life saving devices. Avoid grouping up in the runout of avalanche terrain above you. Avoid slopes with terrain traps.

The video below shows how stubborn this persistent slab is and how much force it takes to propagate the slab, but the consequence can’t be ignored.

 

The Facet Culprit

 

 

 

 

Recent Avalanche Activity

Dry loose sluffs were observed earlier in the week, however, due to limited visibility and ping-pong ball conditions- avalanche observations were limited this week. Due to significant amounts of new snow, loose snow sluffs are expected on steep slopes on all aspects, mostly at mid and upper elevation.

Recent Weather

This week’s weather at 3550′:

Temps averaged 15ºF, with a low of -4ºF and a high of 33ºF.

IM snotel reported 7″ of new snow with .6″ water on 2/17-18.

IM snotel reported 9″ of new snow with .5″ water on 2/22.

Im snotel reported 4″ of new snow with .2″ water on 2/24.

Observations in the field have confirmed more snow than indicated on the snotel site with totals reaching 24″ or more.

 

Overnight at 3550′:

No new snow overnight.

 

This week’s weather at 4500′:

Temps this week averaged 12ºF.

Winds averaged 5 mph, gusts 10 mph SE. Wind gusts increased to 15-28 mph SE Thur 2/23 and Friday 2/24.

 

Overnight at 4500′:

Temps averaged 18º F overnight.

Winds averaged 3 mph, gusting 12 mph SSE.

 

 

 

Additional Info & Media

   The avalanche hazard will remain the same throughout the weekend. If the wind starts to blow, expect the avalanche hazard to rise.


NWS rec forecast here.


State Parks Snow Report for February 24, 2017 here.

Posted in HPAC Forecasts.
Allie Barker

Forecaster: Allie Barker