Tuesday-Friday 2/14-17

Issued: Tue, Feb 14, 2017 at 8AM

Expires: Fri, Feb 17, 2017

Over the last 36 hours, high quantities of snow accumulation followed by extensive rain on dry snow has led to unstable snowpack conditions.

Travel in avalanche terrain is NOT recommended.

Monitor the bonding of new to old and for density variations in the storm slab that could be the weak link.

Rain on new snow can quickly destabilize the structure and lead to avalanches.

Do not linger in or below avalanche terrain and expose only one at a time when necessary.

Above 2,500ft High

1,800 to 2,500ft High

Below 1,800ft High

Degrees of Avalanche Danger ?

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

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

TUESDAY WEDNESDAY THURSDAY & FRIDAY

DANGER SCALE

STORM SNOW:

Elevation: All
Aspect: All
Terrain: All
Sensitivity: Responsive
Distribution: Wide Spread
Likelihood (Human Triggered): Likely
Size: Small – Large
Danger Trend: Increasing
Forecaster Confidence: Good

WET AVALANCHES:

Elevation: All
Aspect: All
Terrain: All
Sensitivity: Responsive
Distribution: Wide Spread with rain on snow
Likelihood (Human Triggered): Possible
Size: Small – Large
Danger Trend: Increasing
Forecaster Confidence: Fair

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:

Maritime (Coastal) Specific: 

3 feet of new snow has likely accumulated in the upper elevations while the last foot fell as rain in the lower elevations of the maritime zone. Above freezing temperatures hit close to 3000′, resulting in extensive rain on dry snow which quickly destabilizes its integrity and has likely led to natural avalanche activity that we just can’t see yet. This could result in both loose wet and wet slab activity. Do not linger below large slopes above….such as in Mineral Creek or Keystone Canyon.

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

Maritime (Coastal) Specific: 

  • Small avalanches in Keystone Canyon
  • Large Avalanche in Snowslide Gulch

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  32 / 34
Ridgetop Wind Forecast (direction/mph): SE / 15-35
Snowfall (in):  1-4
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction   Calm  24 / SE
Max Wind Gust (mph) / Direction  9 / W  42 / SE
Temperature Min / Max (*F)  29 / 36  27 / 32

Weather Forecast:  As warm air has continue to make inroads into our surrounding mountains, rain and or wet snow has crept into the higher elevations. Thompson Pass is holding just below freezing, while the Upper Tsaina and 46 Mile has tipped just over the mark likely leading to wet snow surfaces. While most of the precipitation has hit us already, up to 3/4 of an inch of more water could fall from the atmosphere, which could mean 8 more inches of snow in the upper elevations. Winds have been steady and strong out of the SE, but will back down this afternoon as precipitations back down and lingers into early Wednesday. The low that has swung this warm-wet system the last couple days should push in some colder air, slightly cooling today and more rapidly Wednesday as clouds will lift. Clouds and random precip seem to plan to linger until late Fri when clearing could ensue.

Additional Info & Media

SNOW HISTORY: Valdez 2/14 AM Thompson Pass 2/14 AM
24 Hour Snow / Water Equiv. 0.0”/0.4″ 10″ /2.2″
Storm Snow /Water Equiv. (2/12-14) 1.6” /0.4″ 20″ /2.7″
Current Snow Depth 49″
February Snow / Water Equiv. 29.8″ /3.62″ 28″ / 3.4″
Total Winter Snowfall / Water Equiv. 208″ / 19.5” 267″ / 26″
Snowload in Valdez 62.4 lbs/sq. ft.

 

SNOWFALL for LAST 24 HRS at OTHER STATIONS (2/13 AM):
Nicks Valley at 4200 ft (in): 18″
Upper Tsaina at 1750 ft (in): 8″+rain?
Sugarloaf at 550 ft (in): 4″+ rain
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 Maritime Forecasts.

Forecaster: Kevin Salys