Wednesday-Saturday 2/8-11

Issued: Wed, Feb 08, 2017 at 8AM

Expires: Sun, Feb 12, 2017

Should be a great day in the mountains – use normal caution focusing on good communication and travel techniques. Steer clear of steep, unsupported slopes and gullies loaded by the north wind.

Above 2,500ft Moderate

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

WEDNESDAY THURSDAY FRIDAY & SATURDAY

DANGER SCALE

WIND SLAB:
Elevation:
 Above 1800 feet elevation
Aspect:
 South and west 
Terrain: 
Steeper than 35 degrees
Sensitivity:
 Stubborn
Distribution: 
Specific
Likelihood (Human Triggered): 
Possible
Size: 
Small – Large
Danger Trend:
 Decreasing 
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:  The last snowfall ended more than a week ago, Jan.31. Since then, the storm snow has settled and bonded to snow beneath. North wind has moved and textured much of the snow.

Feb.1-5 was the return of sun affect: solar radiation and warm daytime temperatures triggered roller balls and loose avalanches on southerly aspects. Hence, the shift from early season to more spring-like snow conditions.

coastal-zone-iconMaritime (Coastal):  Good settlement of the end of January storm snows with no significant weak layers. North wind redistributed snow near ridgetops and peaks.

intermountain-zone-iconInter-Mountain (Transitional):  

  • Near ridgetops and wind channeled terrain, the north wind has transported the unconsolidated surface snow and formed windslab on leeward slopes.  Much of the high ground is wind affected and scoured. Many pockets of hard windslab naturally popped off rollovers and steep gully ways last weekend with little to no new activity since. Poke around to see how the windslab is bonded to layers below.
  • Soft snow is still found in wind protected valleys. Some surface hoar observed.

interior-zone-iconContinental (Interior):  

  • Consistent cold, dry weather has faceted and dried out the 3 feet or less of snow on the ground inland of mile 37. Wind above treeline has scoured windward slopes and loaded leeward gullies. Near surface facets and some surface hoar have been observed.

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):

  • No new observations reported.

intermountain-zone-iconInter-Mountain (Transitional):  

  • No new observations reported.

interior-zone-iconContinental (Interior):  

  • No new observations reported.

 

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  5 / 22
Ridgetop Wind Forecast (direction/mph): S / 5-15
Snowfall (in):  1
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction   3 / NE  10 / NE
Max Wind Gust (mph) / Direction  15 / NE  19 / NE
Temperature Min / Max (*F)  16 / 30  4/ 13

Weather Forecast:    Slightly cooler this morning, then clouds moving in this afternoon. Temperatures will warm slightly as light snow falls, accumulating only 1-2″ Thursday. Wind is shifting to the south, but will be back out of the north by Thursday mid-day. No significant precipitation until next week.

Additional Info & Media

SNOW HISTORY: Valdez 2/8 AM Thompson Pass 2/8 AM
24 Hour Snow / Water Equiv. 0”/0″ 0″ /0″
Storm Snow /Water Equiv. (1/31) 0” /0″ 3″ /0.2″
Current Snow Depth 37″ 36″
February Snow / Water Equiv. 2.73″ /0.17″ 3″ / 0.2″
Total Winter Snowfall / Water Equiv. 175″ / 16.01” 242″ / 22.8″
Snowload in Valdez 50 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 Maritime Forecasts.
Pete Carter

Forecaster: Pete Carter