Issued: Sat, Feb 10, 2018 at 7AM

Expires: Sun, Feb 11, 2018

Join us tonight!!!

Hatcher Pass Avalanche Center Annual Fundraiser and Cabin Fever Reliever,

TONIGHT, Saturday, February 10th at the Moose Lodge in Palmer, 1136 S Cobb St, Palmer, AK 99645

Get your tickets online here! or cash only at Backcountry Bike and Ski or Active Soles in Palmer. Come show your support for your local avalanche center and dance the winter blues away!

Above 3,500ft Moderate

2,500 to 3,500ft Moderate

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

BOTTOM LINE

A Moderate Hazard exists for Persistent Slab Avalanches.  Buried persistent weak layers, both near the surface and in the mid-pack, will be possible to human trigger at mid and upper elevations in specific areas.  Natural avalanche are unlikely. Small avalanches in specific areas; or large avalanches in isolated areas.

A Low Hazard exists at low elevation.

 


PERSISTENT SLAB AVALANCHE PROBLEM

A Moderate Hazard exists for Persistent Slab avalanches at mid to upper elevations. A Low Hazard exists at low elevation.

Strong Easterly winds on February 2-3, gusting to 59 mph, scoured windward slopes and loaded leeward aspects, building stiff, cohesive slabs over weak, persistent layers.  Numerous natural avalanches occurred during and shortly after the wind event, mostly at mid to upper elevations on Southwest to Northwest aspects. Slab thickness varied from a few inches to 2 feet deep. Weak layers were both near surface faceted grains and buried surface hoar. These layers will continue to be the layers of concern today.

Stability has increased substantially since this event, however, it will still be possible to trigger cohesive slabs sitting over buried persistent weak layers (near surface facets and surface hoar) up to 2-3 feet deep, up to D2 in size, in specific areas. Likely locations include mid to upper elevation, previously wind loaded slopes and cross loaded features, mostly on Southwest to Northwest aspects, on slopes 30° and steeper. These areas will have a smoother surface appearance than the safer windward aspects which are highly textured.

This avalanche problem will be difficult to predict and any single instability test will be unreliable. The thickness of these slabs varies greatly. It will be more likely to trigger an avalanche where the slab is thinner, where your weight can more easily transfer to the buried weak layers. Any failure of the weak layer will have the ability to propagate (travel) into much thicker portions of the slab problem, increasing the overall size of the avalanche, and therefore the danger and consequences. It will be possible to remotely trigger avalanches from above, below, or adjacent to problem areas. This avalanche problem may also allow for numerous people to successfully ride on slope, before it finally fails, or it may choose to fail on the first rider, it’s a crap shoot.

If you are in and around this hazard, travel one at a time, space out between partners, use islands of safety for decision making points, only have one person on slope at a time, do not group up in the runnout zone. Everyone in your group should be carrying a beacon, shovel and probe on their person, and be prepared and practiced to perform companion rescue.

Pit profile here

Recent Avalanche Activity

No natural of human triggered avalanches have been reported since February 4.

Hiker triggered avalanche on February 3, Marmot, SSW, ~2800′

Close up of picture above

Observed Feb 8 – Marmot SW Face, 4000′, Crown from natural avalanche likely Feb 2 from strong wind loading overloading weak facets and surface hoar. HS-N-R2D2-I

Same as above

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Debris from avalanche pictured above

 

 

 

 

 

 

 

 

 

 

 

 

 

Observed Feb 8 – Natural avalanche from Feb 2 wind event, debris filled the terrain trap in the creek below. HS-N-R1D2-I

 

 

 

 

 

 

 

 

 

 

 

 

 

Observed Feb 8 – Natural avalanche debris from Feb 2 in the terrain trap under Southeast faces of Marmot, near presidents.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Feb 8 – Surface Texture

Strong east winds on Feb 2 scoured Marmots southeast aspects and loaded the SW faces.

Feb 8 – Wind sculpted texture

 

 

 

 

 

 

 

 

 

 

 

 

 

Feb 8 – Surface Hoar forming

 

Feb 8 – Wind scoured areas have thin snowpacks, consisting completely of 18-24″ inches F to 4F facets, 1.0-4.0 mm

 

Recent Weather

An inversion continues to persist in our area. At 7AM the temperature at the Palmer Airport is 7°F and RH 87%, while the temperature on Marmot Mountain at 4500′ is 25ºF wit a RH of 20%.

This week’s weather at 3550′:

Temps averaged 20ºF, with a low of 11ºF and a high of 30ºF.

1″ of new snow this week.

Overnight at 3550′:

Temps averaged 24° F.

0″ new snow overnight.

This week’s weather at 4500′:

Temps averaged 23ºF, with a low of 14ºF and a high of 31ºF.

Winds averaged SE 4 mph, max SE 13 mph . Gusts averaged SE 7mph, max gusts SE 20 mph.

Overnight at 4500′:

Temps averaged  25ºF overnight, with a Low of 24ºF .

Winds averaged SE 6 mph overnight, with a max gust of SE 18 mph.


NWS recreational forecast for Hatcher Pass here


NWS point forecast here


State Parks snow report here

Additional Info & Media

Snow is in the forecast starting tonight and through Monday. A few inches of new snow will increase the likelihood of triggering small, dry loose avalanches Sunday through Monday. While NWS is only calling for a few inches, strong SW flow has the potential for heavy precipitation at HP. Any rapid, heavy load will have the potential to increase the avalanche hazard for higher consequence slab avalanches.

 

Pictured here, Upper Air on the NAM model, Midday Sunday. SW flow generally brings HP larger snow accumulations

 

 

 

 

 

 

 

 

 

 

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Posted in HPAC Forecasts.
Allie Barker

Forecaster: Allie Barker