Hatcher Pass Avalanche Center

Hatcher Pass Avalanche Forecast RSS

Archives
ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Sat, January 26th, 2019 - 7:00AM
Expires
Sun, January 27th, 2019 - 7:00AM
Forecaster
HPAC Staff
The Bottom Line

Strong winds combined with 3-4″ of new snow since 1/24 have created a CONSIDERABLE avalanche hazard for newly formed wind slabs at upper elevations, on Northwest to Northeast aspects, on slopes 35° and steeper.

Avoid slopes with terrain traps, as any size avalanche may be able to carry or wash a person into terrain traps, significantly compounding the hazard.

New snow may conceal a generally shallow snowpack. Be cautious of shallowly buried hazards, such as rocks.

Thanks to our sponsors.
Sat, January 26th, 2019
Upper Elevation
Above 3,500'
Considerable (3)
Avalanche risk
Mid Elevation
2,500'-3,500'
Moderate (2)
Avalanche risk
Low Elevation
Below 2,500'
Low (1)
Avalanche risk
Upper Elevation
Above 3,500'
Avalanche risk
Considerable (3)
Mid Elevation
2,500'-3,500'
Avalanche risk
Moderate (2)
Low Elevation
Below 2,500'
Avalanche risk
Low (1)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Recent Avalanches

No new avalanche activity has been observed or reported this week.

Strong winds combined with new snow may have triggered some natural wind slab and loose dry avalanches over the last 24 hours, but no reports are available as of this morning.

Avalanche Problem 1
  • Wind Slabs
    Wind Slabs
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
More info at Avalanche.org

Since 1/24 strong SE, S and SW winds, with gusts up to 54 mph, have transported snow and built new wind slabs. 3-4″ of new snow acculated at 3000-3500′ with more likely at upper elevations since 1/24, but accurate measurement of this new snow is difficult to judge as winds have effected weather station data. The thickness and scale of wind slabs will be limited as not much snow was available for transport.

Expect wind slabs, sitting on smooth surfaces and weak, sugary snow, to be likely to human trigger up to 4-10″ thick, in specific locations, generally leeward to the winds, on NW to NE aspects, at upper elevations on slopes 35º and steeper. Some natural activity may be possible today at upper levations.  At mid elevations this hazard is moderate, and at low elevation this hazard is Low. Likely terrain features containing wind slabs are along ridges, gully sidewalls, and in gaps and passes. Pay attention to cross loaded features and for the possibility of strong winds to have deposited wind slabs mid slope.

Shooting cracks, whumphing, and recent avalanche activity are bulls-eye clues for a sensitive wind slab avalanche problem. Pole and probe tests and hollow sounding snow may aid in identifying firm wind slabs sitting on weaker snow beneath.

Avalanche Problem 2
  • Dry Loose
    Dry Loose
Dry Loose
Dry Loose avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.
More info at Avalanche.org

Loose dry, new snow sitting on widespread, old, firm, smooth surfaces will likely have produced some small natural activity over the last 24 hours. Natural activity is unlikely today. Human triggered, small, loose dry avalanches will be possible on all aspects, on slopes 40° and steeper today, in wind protected areas. At mid to upper elevations, in very isolated, wind protected locations, new snow will be sitting on up to a foot and a half of loose, weak, sugary snow. Triggering a lose dry avalanche under these conditions will entrain older, sugary snow and result in fast moving sluffs with more volume. Loose dry avalanches will generally be on the small side, but may have the ability to carry a person into secondary hazards, such as terrain traps, compounding the hazard.

Weather
Sat, January 26th, 2019

This week’s weather at 3550′:

Temps averaged 25ºF, with a low of 11ºF and a high of 36ºF.

3-4″ of new snow accumulated from 1/24 through this morning. Accurate measurements of recent precipitation totals are difficult to judge as strong winds have been scouring and loading weather station instruments since 1/24.

Overnight at 3550′:

Temps averaged 25°F.

No new snow.

This week’s weather at 4500′:

Temps averaged 22ºF, with a low of 9ºF and a high of 29ºF.

Winds averaged SE 11 mph, max 42 mph . Gusts averaged SE 11 mph, max gust SSE 56 mph.

Overnight at 4500′:

Temps averaged 18ºF overnight, with a Low of  16ºF.

Winds averaged SW 6 mph overnight. Max gust SSW 34 mph.


Marmot winds since 1/24:

 

 

 

 

 

 

 

 

 


NWS Rec Forecast HERE


NWS point forecast HERE


State Parks Snow Report and Motorized Access information HERE


TREND

The avalanche hazard, for wind slabs in particular, will remain the same through today and begin to improve tomorrow as the snowpack has a chance to adjust to new loads.

The NWS Hatcher Pass recreational weather forecast for today:

                Today        Tonight

Temp at 1000`      31 F         24 F

Temp at 3000`      21 F         26 F

Chance of precip   60%          20%

Precip amount
(above 1000 FT)    0.07 in      0.01 in

Snow amount
(above 1000 FT)    0-1 in       trace

Snow level         sea level    sea level

Wind 3000` ridges  SE 9-18 mph  SE 8-15 mph

 

Observations
Recent Observations for Hatcher Pass