Hatcher Pass

Forecast as of 03/30/2019 at 07:00 am and expires on 03/31/2019

Above 3,500ft Moderate

2,500 to 3,500ft Considerable

Below 2,500ftConsiderable

Degrees of Avalanche Danger

Problem Details

UPDATE: Saturday 3/30 at 5pm, expires in 24 hours

Low danger in the morning will rise to CONSIDERABLE by mid day for WET loose and WET slab avalanches, up to D2, on SE to SW aspects, on slopes above 30º, at all elevations. Natural avalanches are possible and human triggered are likely. Large avalanches in specific areas will be possible. A large human triggered wet slab occured today at 11:45am on the SE aspect of Skyscraper, large enough to bury, injure, or kill.Wet slabs are hard to predict and can be remotely triggered. Despite overnight freezing, daytime temps are RISING RAPIDLY and may catch you off-guard. 


 

BOTTOM LINE

The avalanche danger today is LOW in the morning, rising to CONSIDERABLE in the afternoon for Wet Avalanches at low and mid elevations, most likely in the afternoon and evening on steep SE to SW aspects. Most avalanches will be small in size although large avalanches up to D2 will be possible on S aspects at low and mid elevation in the pm. A MODERATE danger exists at upper elevation for wet avalanches in the afternoon on SE to SW steep slopes.

Cornices are huge and will be possible for a human or dog to trigger today. Cornices will have the potential to trigger larger sluffs or slab avalanches that may fail to the ground. Large cornice chunks have been observed below many leeward slopes.

A slightly cooler trend this week with overnight freezing temperatures at upper elevation has significantly improved conditions. Time of day and aspect choice will be key for pure enjoyment, staying safe, and avoiding avalanches.


PREVIOUS ADVISORIES AND UPDATES HERE

 

 

Problem 1: Cornice

Cornice failures, either naturally, or human triggered, will be possible today up to D2 or larger in size, on leeward aspects at upper elevation. This is a high consequence hazard.

A large cornice fall triggered a D2 persistent slab this week in the Rae Wallace chutes. Last week, a dog triggered a cornice fall that triggered a D1.5 persistent slab to the ground.

Cornices are large and can be difficult and dangerous to assess. Our recommendation is to assume that cornices are LARGE on all leeward aspects at upper elevation, and to give cornices a wide berth of 20 feet or more. Cutting cornices of this size as a stability tool is not recommended nor effective.  

 

Above: Significantly weakening Cornices Top of Cable Valley West Pass

 

 

 

More about cornice fall in the avalanche problem toolbox, HERE.

 


Problem 2: Wet Loose

A solid overnight freeze will keep most snow surfaces frozen this morning at mid and upper elevation.  Natural avalanches will be possible today, and human triggered avalanches will be likely in the afternoon on SE to SW aspects at mid and low elevations, mostly small, but up to D2 on S aspects, on slopes 40° and steeper.  It will be possible to human trigger mostly small ,wet loose at upper elevation on steep SE to SW aspects in the afternoon. 

Natural, wet loose avalanches have been observed all week, mostly on southerly aspects. Some have trenched to the ground.

A small wet loose avalanche can easily treek a knee, or push you into terrain traps.

Timing is key to your safety. The snow will transition through the day. Pay close attention to the snow surface. As it heats through the day it will become increasingly saturated. Wet snow, deeper than your ankles, will be dangerous on slopes 40 degrees and steeper, and become more likely to entrain snow, increasing the likelihood and consequence of any wet-loose. Wet-loose sluffs are avoidable with good decision making and terrain choices.

 

 

Above: 3/28 It all starts with a pinwheel...natural wet loose SE Marmot, 3500'.

 

More about wet avalanches in the avalanche problem toolbox, HERE.


 Problem 3: Wet Slab

Wet slabs will be possible to human trigger on SE to W aspects at mid and upper elevation on slopes 30° and steeper, and up to D2 in size, in the afternoon. Poor structure and the lack of a slab will alleviate this concern at low elevation in most locations.  

Wet slabs have also been sympathetically triggered by wet loose avalanches this week. For the most part, wet slabs are hard to predict. We did observe 3-5 natural wet slabs on SE to SW aspects this week. Expect the wet-slab cycle to continue and grow in size as spring weather continues.

 

 

Above: 3/28 Natural wet-slab on W/SW aspect up Archangel Valley at approx 3500'.

 

 

 

 

 

 

Avalanche Activity

Natural and human triggered wet-loose and natural wet-slabs were observed most of the week. Most wet-loose were small in size, in terrain 40° and steeper, and on ALL aspects, and all elevations. The largest avalanches were up to D2 in size, at all elevations, on SE to S aspects.  

Many large cornices have failed naturally, triggering persistent slab avalanches. Large to extra large cornice chunks have fallen naturally too.

Above: 3/29 Large wet-loose archangel valley, SE aspect, 3700'.

 

Above: 3/29 Natural wet loose to the ground near Presidents of Marmot, SE aspect 3400'

Above: 3/29 Wet loose and wet-slab. 4500' SE Birthday / High Grade Pass.

Above: 3/29 Large cornices exist on many upper elevation leeward aspects and have been breaking naturally this week. Friendship Pass.

 

 

For more info and pictures on the Natural and Human triggered avalanches this week , check out the mid week summary, HERE or weekly OBSERVATIONS HERE.

 

 

Weather

This week’s weather at Independence Mine 3550′:   

Temps averaged 33ºF, with a low of 25ºF and a high of 43ºF.

IM recorded 4” of new snow and .3" water (SWE) since 3/23.  

Overnight at 3550′:

Temps averaged 28°F.

No new snow.

This week’s weather at Marmot Weather Station 4500′:

Temps averaged 28ºF, with a low of 22ºF and a high of 40ºF.

Winds averaged SSE 5 mph, max 17 mph . Gusts averaged SSE 9 mph, max gust SSE 27 mph.

Overnight at 4500′:

Temps averaged 24ºF overnight.

Winds averaged E 3 mph overnight. Max gust E 9 mph.


NWS Rec Forecast HERE


NWS point forecast HERE


State Parks Snow Report and Motorized Access information HERE

Additional Information

TREND    

Avalanche danger will remain the same until we see a continued lack of freezing at night. Sunny skies, warm days, and freezing temps at upper elevation should persist through the weekend. 

Alerts

Read entire HPAC advisory HERE.

Announcements

UPDATE: Saturday 3/30 at 5pm, expires in 24 hours

Low danger in the morning will rise to CONSIDERABLE by mid day for WET loose and WET slab avalanches, up to D2, on SE to SW aspects, on slopes above 30º, at all elevations. Natural avalanches are possible and human triggered are likely. Large avalanches in specific areas will be possible. A large human triggered wet slab occured today at 11:45am on the SE aspect of Skyscraper, large enough to bury, injure, or kill. Wet slabs are hard to predict and can be remotely triggered. Despite overnight freezing, daytime temps are RISING RAPIDLY and may catch you off-guard. 


BOTTOM LINE for March 30 at 7am, expires in 24 hours.

The avalanche danger today is LOW in the morning, rising to CONSIDERABLE in the afternoon for Wet Avalanches at low and mid elevations, most likely in the afternoon and evening on steep SE to SW aspects. Most avalanches will be small in size although large avalanches up to D2 will be possible on S aspects at low and mid elevation in the pm. A MODERATE danger exists at upper elevation for wet avalanches in the afternoon on SE to SW steep slopes.

Cornices are huge and will be possible for a human or dog to trigger today. Cornices will have the potential to trigger larger sluffs or slab avalanches that may fail to the ground. Large cornice chunks have been observed below many leeward slopes.

A slightly cooler trend this week with overnight freezing temperatures at upper elevation has significantly improved conditions. Time of day and aspect choice will be key for pure enjoyment, staying safe, and avoiding avalanches.


Announcements:

Heading to Turnagain? Be sure to check the CNFAIC Forecast HERE.