Friday-Monday 1/27-1/30

Issued: Fri, Jan 27, 2017 at 8AM

Expires: Mon, Jan 30, 2017

Cooling temperatures will aid in the solidifying the rain soaked snow in the lower elevations as new snow stacks up on icy surfaces that it won’t bond well to.

In the upper elevations, thickening storm slabs with moderate southerly winds and poor visibility should lead to conservative travel choices.

Above 2,500ft Considerable

1,800 to 2,500ft Considerable

Below 1,800ft Moderate

Degrees of Avalanche Danger ?

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

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

FRIDAY SATURDAY SUNDAY & MONDAY

DANGER SCALE

STORM SNOW:
Elevation:
 All
Aspect: 
All
Terrain: 
Steeper than 35 degress
Sensitivity: 
Reactive
Distribution: 
Widespread
Likelihood (Human Triggered): 
Likely
Size: 
Small – Large
Danger Trend:
 Increasing 
Forecaster Confidence: 
Good

PERSISTENT SLAB:
Elevation: 
Mostly above 2500′
Aspect: 
All
Terrain: 
Steep rocky slopes where facets exist under old and between windslab, especially interior of Thompson Pass
Sensitivity: 
Stubborn
Distribution: 
Specific
Likelihood (Human Triggered): 
Unlikely
Size: 
Small – Large
Danger Trend: 
Increasing with load
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: While 1/2 of an inch of rain soaked the lower elevations in town and the maritime zone (rain line was likely up to 1200′ and pushed inland all the way to Milepost 19 yesterday), up to 20 inches of snow continued to stack up at the pass since Jan. 23rd. Highest numbers of new snow were near Thompson Pass proper, while those numbers were nearly halfed (~1 f00t) down near the Tsaina River and possibly less out at Milepost 46. The new snow seems to be sticking well to old snow surfaces (faceted sugar old snow, surface hoar, and windslab) buried Jan 23rd with no clean failures in assessment. Consistent onshore winds from the SE have been moderately drifting snow to lee slopes throughout this chain of fronts. Soft wind slab formation in very exposed areas is likely compounding storm snow instabilities.

 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):

  • Jan 26: Widespread wet snow releases below the rain line: Above town and airport; Keystone Canyon; poor visibility limited observations
Highschool Hill Loose Wet Avalanches Thursday

Highschool Hill Loose Wet Avalanches Thursday

  • Jan 25: Storm snow instabilities: Keystone Canyon Steeps.

intermountain-zone-iconInter-Mountain (Transitional):  

  • No new observations.

interior-zone-iconContinental (Interior):  

  • No new observations.

 

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  28 / 29
Ridgetop Wind Forecast (direction/mph): SE / 5-30
Snowfall (in):  5-7
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction   2 / var  20 / ESE
Max Wind Gust (mph) / Direction  11 / W  29 / SE
Temperature Min / Max (*F)  31 / 38  24 / 30

Weather Forecast:     As temperatures cool in our area and lock up all the rain soaked snow, look for snow flurries today and into early Saturday as a low pressure system seems to want to track directly at Cordova. Depending on its true path, our numbers on falling water could vary, but could reach up to 7 more inches of snow by Saturday morning. Skies and precipitation look like they could begin to break up for the weekend until a stacked low system moves quickly into the gulf and impacts us by Sunday night and into next week.

Additional Info & Media

SNOW HISTORY: Valdez 1/27 AM Thompson Pass 1/27 AM
24 Hour Snow / Water Equiv. 0.1” /0.5″ 3″ /0.3″
Storm Snow /Water Equiv. (1/23-27) 24.7” /2.1″ 20″ /1.7″
Current Snow Depth 46.8″ 41″
January Snow / Water Equiv. 71.7″ /5.3″ 74″ / 5.9″
Total Winter Snowfall / Water Equiv. 167.8″ / 15.1” 217″ / 20.3″
Snowload in Valdez ? lbs/sq. ft.

 

SNOWFALL for LAST 24 HRS at OTHER STATIONS:
Nicks Valley at 4200 ft (in): 4″
Upper Tsaina at 1750 ft (in): Trace?”
Sugarloaf at 550 ft (in): Rain
SNOW DEPTH & WATER SURVEY (1/3/2017) Depth Snow Water Equivalent
Milepost 2.5 Valdez  22.7″  4.7″
Milepost 18 27.9″ 5.9″
Milepost 29 Worthington Flats 44″ 9.9″
Milepost 37 Tsaina River bridge 33.8″ 5.6″
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