Issued: Mon, Mar 19, 2018 at 10AM

Expires: Tue, Mar 20, 2018

Large Natural Avalanche on Marmot crossed the road at mile 15.5 near Archangel at 8:30 am this morning.

11″ of new snow has rapidly fallen overnight. It has been snowing 2″/hr for the past 4 hours. More snow and wind are expected today.

Very dangerous conditions. Travel in avalanche terrain NOT recommended. Natural avalanches are likely, human triggered very likely. Expect large avalanches in many areas or large avalanches in specific areas.

The road will be CLOSED. Please let DOT and Avalanche Forecasters do their work. Do not attempt to drive up the road or ski up the road run. The road run is in the RUNOUT of avalanche danger.

Above 3,500ft High

2,500 to 3,500ft High

Below 2,500ft High

Degrees of Avalanche Danger ?

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

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

BOTTOM LINE

An avalanche has crossed the Willow-Fishhook Road at mile 15.5 and the road is being closed.

Travel in avalanche terrain is not recommended. New snow has overloaded the snowpack and avalanches are likely today.

Marmot Gully 1 and 2 . Natural avalanches that crossed road 3/19.

 

Almost to the 8′ mark!

 

For more information and pictures, see OBSERVATIONS HERE.

Recent Avalanche Activity

 For the most part, visibility was poor this week. It is likely that more natural avalanches occurred since the new snow and wind 3/14-3/16. Two naturals were observed 3/16.

1.Arkose Ridge- W/NW 4000′ SS-N-D2.5-O

2.Marmot Mid Rib- half way down SE 3600′ SS-N-D1-S

3.Several wet-loose sluffs were observed at low elevation along the roadway on the drive down Friday night.

 

 


Check out the photos below. The first one went naturally last week 3/9. The second photo (lookers right of this avalanche) went naturally 3/15 or 3/16. The same problem lingers.

3/9 Arkose Ridge NW 4000′ Natural wind slab appears to have stepped down to old persistent slab and triggered sympathetic avy below. Debris ran to top of icefall.

Arkose Ridge 4000′ W/NW Natural 3/15 or 3/16 Suspected wind slab that failed on old persistent weak layer

 

 

 

 

 

Arkose Ridge, same photo as above Notice how avalanche wrapped around gully. Poor widespread structure is the culprit.

 

 

 

 

 

 

 

 

 

Recent Weather

This week’s weather at 3550′:

Temps averaged 22ºF, with a low of 15ºF and a high of 34ºF.

IM reported about 14″ of new snow between 3/14 and 3/16 with 1.3″ of water (SWE).

Overnight at 3550′:

Temps averaged 27° F.

No new snow overnight.

This week’s weather at 4500′:

Temps averaged 19ºF, with a low of 12ºF and a high of 30ºF.

Winds averaged ESE 5 mph, max ESE 16 mph . Gusts averaged ESE 10 mph, max gusts SE 25 mph.

Overnight at 4500′:

Temps averaged  22ºF overnight.

Winds averaged SSW 3 mph overnight, with a max gust SSW 5 mph.

 


NWS recreational forecast for Hatcher Pass here


NWS point forecast here


State Parks snow report here

Additional Info & Media

Expect the avalanche hazard to remain HIGH today and Tuesday.

100% chance of precipitation today with another 6-9″ of snow possible.

Winds 8-23 G35 mph. Snow intensity decreasing throughout the day.

 

Posted in HPAC Forecasts.
Allie Barker

Forecaster: Allie Barker