Thursday-Sunday 1/19-1/22

Issued: Thu, Jan 19, 2017 at 8AM

Expires: Sun, Jan 22, 2017

Continuously strong winds out of the NE are rapidly moving and creating SENSITIVE WINDSLABS (already seen yesterday) on lee aspects near ridges, gullies, rollovers, and bowls.

Despite sunshine, severe wind chills will result in bundling up and lack of vitamin D. Be prepared for longer than expected forays away from a heat source.

 

Above 2,500ft Considerable

1,800 to 2,500ft Moderate

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′
Aspect: Shifting winds have loaded (top and cross-loaded) all aspects exposed to wind in the last week
Terrain:
Ridges, gullies, bowls, rollovers
Sensitivity:
 Touchy
Distribution:
 
Specific
Likelihood (Human Triggered): 
Likely
Size:
 Large
Danger Trend: 
Steady
Forecaster Confidence: 
Good

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: Coverage isn’t much better than before the Jan.13-17 storm that laid down 54 inches of snow. Both south and north winds have stripped and redistributed the new snow. Now, a strong northeast wind is once again wreaking havoc on our mountain slopes.  Expect firm windslab depths to 3 feet or more on lee features. In semi-protected areas, soft windslabs were easily sliding off of steep rollovers on Wednesday. The cold temperatures, near or below zero F, at Thompson Pass and inland will slow the bonding of fresh windslab to old surfaces.

In wind protected areas, the storm snow has settled quickly and has formed a soft, supportable slab with wind skin in areas. Luckily, the recent storm snow seems to be bonding quite well despite its weak nature in relation to overlying new windslabs. Failures have been non-planar breaks that won’t support propagation.

In the lower part of the firm midpack, below our knife-hard wind slabs from early this year, old facets are firming and tending to holding tight to eachother.

Most unsettling are scattered areas with a structurally weak base of sugar snow that is precariously holding up heavy mid and upper slab layers. Large whumphs were reported Tuesday near the Worthington Glacier, reminding us we cannot fully trust this snowpack yet: especially in areas that are colder with a thin snowpack (inland of MP 33 where these conditions are more likely to be found).

It is still possible for smaller upper layer avalanches to step down to deep old persistent weak layers and create very large events.

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

Even with great visibility, not much large avalanche activity was observed Wednesday. Many upper, exposed areas were dramatically scoured. Several small, loose dry avalanches in very steep, rocky terrain throughout the corridor next to the road. Significantly less snow hit the continental and northern part of the inter-mountain zones. Please share what you see.

coastal-zone-iconMaritime (Coastal):

  • Dec. 17: Reported mid-storm debris below the N face of Benzine sliding into the popular ski line.

intermountain-zone-iconInter-Mountain (Transitional):  

  • Dec 18: Max High Peak had some old-ish (mid-storm?) debris below the SE aspect at about MP 35 (see Trevor’s map link below for location)

interior-zone-iconContinental (Interior):

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  -11 / -3
Ridgetop Wind Forecast (direction/mph): NE / 10-45
Snowfall (in):  0″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction   12/ ENE  42 / NE
Max Wind Gust (mph) / Direction  28 / ENE  57 / NE
Temperature Min / Max (*F)  15 / 23  -3 / 3

Weather Forecast: Clear, cold and crisp winds will be the story of the day. Clouds, dropping winds and warming temps could arrive Friday as a low pushes east off the Bering and over mainland. Model variance leads to a bit of uncertainty as to the track of this low and how it will impact us. Don’t dream of too much precipitation, but at least the brutal temps and wind will shift this weekend.

Additional Info & Media

SNOW HISTORY: Valdez 1/19 AM Thompson Pass 1/18 AM
24 Hour Snow / Water Equiv. 0” /0” 1″ /0.01″
Storm Snow /Water Equiv. (1/13-1/17) 46.4” /3.2″ 54″ /4.2″
Current Snow Depth 37″ 36″ (wind scoured)
January Snow / Water Equiv. 46.4″ /3.2″ 54″ / 4.2″
Total Winter Snowfall / Water Equiv. 44.9″ / 13” 197″ / 18.6″
Snowload in Valdez 27.56 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 (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