Friday-Monday 4/14-4/17

Issued: Fri, Apr 14, 2017 at 8AM

Expires: Mon, Apr 17, 2017

Tonight!!! April 14: VAC Full Moon Spring Fling FUNraiser with Acoustic Avalanche at the Tsaina Lodge.   Grab a date and come boogie! Fire dancing, DJ and raffle too!

Recent wind out of the NE has moved large amounts of loose snow and and formed fresh wind slabs on lee aspects terrain features….evaluate bonding and possible weak layers underneath.

Spring conditions are here with rising hazard in the afternoon! As the sun warms and weaken snow on steep southerly faces, plan your day appropriately….limiting exposure to avalanches from above.

Above 2,500ft Moderate

1,800 to 2,500ft Moderate

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

 

WET AVALANCHES:
Elevation:
   Below 5000′
Aspect:
   East in AM, bearing South, then West in PM
Terrain:
Steep terrain near rocks and vegetation.
Sensitivity:
   Touchy when warmed.
Distribution:
   Specific.
Likelihood (Human Triggered):
  Possible
Size:
  Small-Large
Danger Trend:
   Increasing quickly each day with warming temperatures, falling at night
Forecaster Confidence:
   Good

WIND SLAB:
Elevation:
   Above 3000′
Aspect:
   Southerlies
Terrain:
Near ridgelines, rollovers and gully walls.
Sensitivity:
   Responsive to Touchy when sitting on sun crust.
Distribution:
   Specific.
Likelihood (Human Triggered):
  Possible
Size:
  Small
Danger Trend:
   Increasing.
Forecaster Confidence:
   Fair

PERSISTENT SLAB:
Elevation:
  Above 2500′
Aspect:
 All
Terrain:
Slopes > 35*
Sensitivity:
   Stubborn on northerlies, Touchy when warmed by sun
Distribution:
   Widespread
Likelihood (Human Triggered):
   Possible
Size:
  Small – Large
Danger Trend:
   Decreasing
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

AVALANCHE PROBLEM TOOLBOX <here>

SNOWPACK DISCUSSION:

Maritime (Coastal) Specific: 

Winds have just backed down after 2 days of strong NE flow. Many areas of soft snow has drifted and blown onto southerly aspects, forming fresh wind slab, sometimes resting on sun crust and triggering easily.

Snow transport Wed, Apr 14 from strong NE outflow.

Dig and look for surface hoar, buried April 9, that was found all the way up to ridgeline. It was seen still standing under new snow near the summit of Girls Mountain and is likely existent in many areas…since it formed widespread prior. No reports yet of avalanches on this weak layer, so let us know if you see something.

It has been 5 days since some snow has fallen and over a week since the last significant snow storm. Quite the variable scenario exisits out there, from sun crust to firm wind board to nice pockets of preserved and faceting snow. Lower to mid elevations are going isothermal quickly with this warm weather. Timing is the name of the game this time of year, plan accordingly and monitor the evening freezing and afternoon warming closely.

Sharing your observations creates an informed community that everyone benefits from at some point.

Recent Avalanche Activity

Maritime (Coastal) Specific:

  • April 12: Numerous natural, wet loose avalanches to size D2.5 from Marshall Pass to the port, large running slides down the south faces west of Mineral creek to the flats/sea level. Many running to ground with dirty debris.
  • April 11: With more direct sun, more wet loose releasing out of steep, south aspects entraining snow to D2.5, sometimes to ground
  • April 7: new natural west aspect in the Books.

      Photo: Bobby Lieberman
  • April 6-8: many wet loose avalanches on south aspects 4500′ and below stepped down and pulled out the last storm slab to old firm surfaces. These large size D3 avalanches ran full path. A few reports of similar activity above 4500′.

Large wet debris running far into flats on south side of Tone’s Temple

Slabs pulling out from wet loose off of southerlies along Worthington Glacier

More fresh releases off Girls Mountain south face.

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  26 / 35
Ridgetop Wind Forecast (direction/mph):  NE / 0-30
Snowfall (in/water equivalent):  0″ / 0″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  8 / Var  25 / NE
Max Wind Gust (mph) / Direction  30 / NE  53 / NE
Temperature Min / Max (*F)  39 / 54  27 / 37

Weather Forecast:     A solid freeze occurred last night after the winds died down and lower high temperatures today will hopefully abate dramatic warming of the snow today. Sun remains the dominant force, but some high clouds will move in this weekend for a brief period. Then more sun and no precipitation for the near future.

Additional Info & Media

SNOW HISTORY: Valdez 4/14 AM Thompson Pass 4/14 AM
24 Hour Snow / Water Equiv.  0”/0.0″ 0″ /0″
Storm Snow /Water Equiv. (3/27-4/6)  16.9″ /4.1″ 24″ /2.4″
Current Snow Depth 28″ 42″
April Snow / Water Equiv. ~″ /1.82″ 8″ / 0.8″
Total Winter Snowfall / Water Equiv. 239.8″ /24.47” 327″ / 31.4″
Snowload in Valdez 65.0 lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS (4/14 AM)/STORM TOTAL (3/27-4/6)/STORM WATER EQUIV.:
Nicks Valley at 4200 ft (in): 0″ / ~16″ / ?”
Upper Tsaina at 1750 ft (in): 0″ / ?” / 1.2+”
Sugarloaf at 550 ft (in): 0″/ 20+rain” / 2.8″
SNOW DEPTH & WATER SURVEY (4/2/2017) Depth Snow Water Equivalent
Milepost 2.5 Valdez  41.9″  11.9″
Milepost 18 40″ 11.9″
Milepost 29 Worthington Flats 62.2″ 19.6″
Milepost 37 Tsaina River bridge 46.3″ 12.5″
This survey is done the first week of each month.

Weather Quicklinks:

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