Thursday-Sunday 1/2-5

Issued: Thu, Feb 02, 2017 at 8AM

Expires: Sun, Feb 05, 2017

Keep your senses tuned in for new wind slab formation on a variety of aspects. Winds have shifted from SE to NE and are loading downwind slopes with sensitive layers.

Get the TRAINING! This Saturday Feb.4 hands-on Avalanche Rescue Workshop 9am-5pm. Valdez Civic Center. FREE for youth 10-18 years old. Brush the rust off those skills so no critical time is wasted during an incident and everyone Lives to Ride Another Day.

This Friday, Feb.3, Luc Mehl, Alaskan adventurer, is sharing his route planning tools before a slideshow of one of his expeditionary traverses. EMBRACING THE APPROACH – TAKING THE LONG WAY TO ALASKA’S MOUNTAINS. 6-9pm. Valdez Civic Center.

Above 2,500ft Considerable

1,800 to 2,500ft Low

Below 1,800ft Low

Degrees of Avalanche Danger ?

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

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

THURSDAY FRIDAY SATURDAY & SUNDAY

DANGER SCALE

WIND SLAB:
Elevation:
 Above 1800 feet elevation
Aspect: 
most 
Terrain: 
Steeper than 30 degrees: rollovers, ridges
Sensitivity:
 Responsive
Distribution: 
Specific
Likelihood (Human Triggered): 
Possible
Size: 
Small – Large
Danger Trend:
 Increasing 
Forecaster Confidence:
 Poor

AVALANCHE PROBLEM SCALE DESCRIPTORS:
Sensitivity: Non-reactive, Stubborn, Responsive, Touchy
Distribution: Isolated, Specific, Widespread
Likelihood: Unlikely, Possible, Likely, Nearly Certain
Size: Small, Large, Very Large (size scale <here>)
Danger Trend: Increasing, Steady, Decreasing
Forecaster Confidence: Good, Fair, Poor

LIST OF AVALANCHE PROBLEMS <here>

SNOWPACK DISCUSSION: A moderate to strong southeast wind has shifted to the northeast, moving the 1-2′ of snow onto a much larger variety of aspects. Human triggered windslab avalanches are possible near rollovers, ridgelines, and upper start zones.

Due to the lack of natural activity and concerning test results involving our buried persistent weaknesses, we have removed the Persistent Slab Problem from our primary concerns. Please let us know if you find anything proving otherwise.

coastal-zone-iconMaritime (Coastal):  Solar radiation and warm air temperatures led to quickly softening/weakening new surface snow (5-7″ that fell Jan. 31). This resulted in widespread loose wet activity in steep southerly terrain on Feb. 1. This very likely will lead to a melt-freeze lens on the snow surface on steep southerly aspects in the maritime. All of this most recent snow rests on rain crusted snow that extends up to ~2500′. Over 1″ of rain fell Jan 26-27 on two feet of storm snow that started Jan.24.

intermountain-zone-iconInter-Mountain (Transitional):  

  • Jan. 31 snowfall built drifts to knee deep. Near Thompson Pass the Jan.24-28 storm snow settled to about two feet with dry powder on top, available for wind transport in exposed areas. Testing Sunday showed a rough break down about 2′ at the new snow/old snow interface. Soft slabs pockets near ridgelines proved reactive with the introduction of significant forces at the edges of the slab.

interior-zone-iconContinental (Interior):  

  • The Jan.24-28 storm delivered about a foot of new snow, which settled to 6 inches of light dry powder over a breakable, more dense layer. This lays over old layers of weaker faceted snow. While there appears to not be concentrated force, basal facets were collapsing Sunday with testing above MP 40. This uncertainty with the interior snowpack, leaves the slim possibility of human triggered avalanches in upper elevation rocky terrain.

Find more photos and observations at the bottom of the page. Sharing your observations creates an informed community that everyone benefits from at some point.

Recent Avalanche Activity

coastal-zone-iconMaritime (Coastal):

  • Feb 1: Widespread loose wet activity (up to D2) in steep southerly aspects during first solar radiation post storm.

intermountain-zone-iconInter-Mountain (Transitional):  

  • Jan 30: MP 42: Human triggered soft slab near ridgeline in wind-loaded pocket from southerly winds
  • Jan 30: Scattered, small loose dry sluffs out of steep, rocky terrain

interior-zone-iconContinental (Interior):  

  • No new observations.

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  13 / 25
Ridgetop Wind Forecast (direction/mph): NE / 25-45
Snowfall (in):  0
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction   5 / variable  28 / NE
Max Wind Gust (mph) / Direction  19 / ESE  47 / NE
Temperature Min / Max (*F)  24 / 38  15 / 23

Weather Forecast:    Warmer air, above freezing in the port, as moved into our region and could linger though the weekend. A high pressure system has parked itself over mainland Alaska, which will leave us with clear skies and support strong outflow (NE) winds through the passes and over peaks at least into Friday. It seems that not much change is in store until late Tuesday when a front forces its way towards with building clouds and some more precipitation.

Additional Info & Media

SNOW HISTORY: Valdez 2/2 AM Thompson Pass 2/2 AM
24 Hour Snow / Water Equiv. 0”/0″ 0″ /0″
Storm Snow /Water Equiv. (1/31) 5.9” /0.4″ 7″ /0.5″
Current Snow Depth 40″ 40″
February Snow / Water Equiv. 2.7″ /0.2″ 3″ / 0.2″
Total Winter Snowfall / Water Equiv. 180.7″ / 16.1” 242″ / 22.8″
Snowload in Valdez 52 lbs/sq. ft.
SNOWFALL for LAST 24 HRS at OTHER STATIONS:
Nicks Valley at 4200 ft (in): 0″
Upper Tsaina at 1750 ft (in): 0″
Sugarloaf at 550 ft (in): 0″
SNOW DEPTH & WATER SURVEY (2/1/2017) Depth Snow Water Equivalent
Milepost 2.5 Valdez  41.5″  9.8″
Milepost 18 43.9″ 9.5″
Milepost 29 Worthington Flats 61.5″ 16″
Milepost 37 Tsaina River bridge 42.1″ 9.3″
This survey is done the first week of each month.

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Thompson Pass RWIS weather station <here>
  • MP 30 Nicks (Happy) Valley weather station at 4200 feet <here> (scroll to Nicks Valley)
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>
  • Further weather resources <here>

SNOW CLIMATE ZONES:

  • coastal-zone-iconMaritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  • intermountain-zone-iconInter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
  • interior-zone-iconContinental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).

Photo of Thompson Pass

 thompson-pass-ski-runs

Interactive Map of Valdez Forecast Areas w/ Many Resource Layers (Trevor Grams)

climate-zones-topoclimate-zones-satellitegoogle-earth1

Run Map of Thompson Pass Area (Sean Wisner) (2MB download)
VAC Run Map Thompson Pass

NEWS: Our region is “one of the snowiest places on earth” – Serendipity / Rendezvous snowfall record set in 1963 <here>.

Free smart phone avalanche forecasts at: http://www.avalancheforecasts.com/

Posted in VAC Forecasts.

Forecaster: Kevin Salys