Avalanche Advisory for Saturday, March 18, 2017 at 7:10am

Issued: Sat, Mar 18, 2017 at 7AM

Expires: Sun, Mar 19, 2017

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Above 3,500ft Low

2,500 to 3,500ft Low

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 LineThe avalanche hazard will be LOW today for persistent slabs and loose snow avalanches (sluffs). Human triggered avalanches are unlikely- but not impossible. Avalanches in isolated areas or extreme terrain. Watch for unstable snow on isolated terrain features. 


Mid-pack persistent slabs exist in specific locations. Cold temperatures and large temperature gradients within the snowpack have allowed stiff, dense slabs to lose moisture to the atmosphere and become less dense and less “slab-like.” This is a small chink in the slabs armor that improves the riding conditions, but does not remove the slab/weak layer problem. This process, near surface faceting, has created square powder near the surface.

Weak basal facets and depth hoar at the base of the snowpack are still present. Persistent slabs 2-4′ deep, on all aspects, mostly at mid-upper elevations, will be stubborn to trigger on slopes 30º and steeper. A patchwork of distribution and a lack of  a continuous slab make finding the right spot to trigger one of these avalanches less likely. Pole or probe tests are a simple way to find stiffer snow overlying weaker snow.




















See Pit here.


Loose snow avalanches will be active on SE-SW aspects at mid to upper elevations on slopes 35º and steeper. Although HP has not received new snow in over 2 weeks, old snow has faceted out, losing it’s ability to bond to it’s neighboring snow, and sluffing naturally due to sun heating and human triggers.

Temperatures are expected to rise to 20º F at 1000′ today. Up until now, cold temps have kept sluffing to a minimum. This can change rapidly with a little heat, a lot of sun, and loose snow (facets) galore.  As spring rounds the corner, pay attention to time of day to anticipate potential sluff activity. Any rapid temperature increase will significantly increase avalanche hazard.

Choose lines wisely, pick appropriate safe zones, spread out ! and remember that terrain traps can compound the consequences of any avalanche. Sluff management, avoidance, and safe terrain decisions can minimize your exposure to this hazard.



Recent Avalanche Activity

No new slab avalanches have been reported or observed this week.

Several small loose sluffs have been observed SW- SE aspects at mid and upper elevation on slopes above 35º.

Natural loose snow avalanches (sluffs), SW aspect 4700′ Pinnacle Bowl.


Current conditions:

For the persistent and determined folk, may you find powder! Webster’s dictionary would likely define the conditions as “variable”: recrystallized (faceted)powder, wind board, old windslab, new windslab, sastrugi, wind waves.

Picture below: Variable conditions still exist 3/17.



Recent Weather

This week’s weather at 3550′:

Temps averaged 8ºF.

No snow accumulation this week.

Overnight at 3550′:

Temperature averaged  2° F overnight.

No new snow overnight.

This week’s weather at 4500′:

Temps averaged 9ºF, with a low of -4ºF and a high of 21ºF.

Wind averaged 5 mph, max 13 mph with gusts averaging 10 mph, max 28 mph E/ESE.

On 3/13 winds gusted NE 22 mph. On 3/14 winds gusted NE 28 mph. On 3/15 winds gusted NE 28 mph.

Winds calmed down Friday.

Overnight at 4500′:

Temps averaged  3º F overnight.

Winds averaged N 2 mph .

Additional Info & Media

   The avalanche hazard will remain the same through the weekend.

AK State Parks snow report for Hatcher Pass here. (Most recent report 3/10.)

NWS point forecast for Hatcher Pass here.


Posted in HPAC Forecasts.
Allie Barker

Forecaster: Allie Barker