19 Nov 2017

November 19, 2017

    AVALANCHE ACTIVITY:

    Not much to report locally, Sz 1 ski cut outside the ski area boundary. Observation below.


    Avalanche involvement in the Lake Tahoe area. Story in article section below.        SAC Pic

AVALANCHE TRAVEL ADVISORY FOR THE AREAS ADJOINING WHISTLER BLACKCOMB AS OF SATURDAY NOVEMBER 18:

Mild temperatures at the mountaintops in the Coast Range Mtns at the beginning of the month followed by rapid cooling resulted in the formation of the November 2nd crust. Temperatures plummeted to -20 C from November 3rd-6th with a weak layer of facets observed to have formed above the crust. We are now calling this the November 9th Crust Fact layer since that was when it was buried by new snow.
The storm cycle that arrived over the past weekend deposited a total of 189cm of storm snow by the time it exited our region on Thursday. A widespread natural avalanche cycle occurred on Tuesday night as strong mountaintop winds deposited 86cm in a 24hr period. A size 2.5 natural avalanche was observed to have run in Whistler Bowl with a crown line of at least 1m. The storm snow layers were observed to remain quite touchy on Wednesday, with slab avalanches easily triggerable down to at least the 1700m elevation. The storm snow layers rapidly settled and gain strength over the next 24hrs with little in the way of slab avalanche activity observed with Avalanche control that was carried out on Whistler Mtn on Thursday. Cornices were the only features that were observed to remain easily triggerable yesterday.
The wind has picked up today redistributing the low density storm snow from earlier this week. Reactive wind slab at alpine and tree line elevations can be found in lee terrain. Cornices will continue to grow in the alpine and remain touchy. Avalanche hazard will increase with the approaching storm tonight into tomorrow
Caution is advised when travelling in any wind loaded terrain features and around corniced ridge lines. A cornice fall may have the potential to trigger a deep slab avalanche on the aforementioned buried weakness that are lurking within our snowpack. As always at this time of year, the bond between our early season snowpack and any glaciated areas or summer firn remains suspect.
Remember that early season conditions persist with many rocky hazards lurking beneath the storm snow in off piste terrain.
Whistler Blackcomb Snow Safety

Observation by Jeff Slack on Saturday: 
I was out in the Symphony/Flute zone today and triggered a decent windslab on a ski cut. It was on the NW aspect of Lesser Flute at around 1850m. The slab was maybe 20-25cm deep at the trigger point, the slidepath was roughly 15-20 metres wide, and it ran for roughly 50-60m. The exact spot is just below a fairly flat knoll about 150m below the summit of Lesser Flute.
It seemed to be a pretty standard leeward deposition below a convexity. It ran on an open, slightly gullied slope, roughly 35 degrees, and the slide came to a stop before the slope flattened out. 
It happened around 2pm, during a period of light snow and moderate winds that seemed to be generally prevailing from the east.
Unfortunately I don't have a photo (light would have been really bad anyways), and all of the figures are rough approximations.Hopefully those details are helpful. Let me know if you have any questions.
Other than that, the riding has been great! Very little wind-effect, dry, fluffy snow with great coverage. I haven't hit a rock yet.

    Observations below from Jeff Van Driel on the Duffy.                                           Jeff Van Driel Pic

Dug a test pit at 2000m on a SW aspect today on the Duffey. -2 with obscured skies, snowing lightly, and light to moderate SW winds. Snow depth was 120cm and the ski penetration was 20cm. The surface was Fist density snow and got progressively denser below. There are two crusts, down 85cm and 100cm, and both have rounding facets associated with them, size 1-2mm. No results on these interfaces. We had a CTH RP down 35 cm on a density change. 
There appears to be good settlement in the snowpack and there are still many early season obstacles. 


                                                                                                                                                             Jeff Van Driel Image



    YESTERDAY:

    Mostly cloudy, trace of new snow recorded at 1660 meters at 14:00 Hrs.


    There were some breaks mid day. High in the valley yesterday was +3.

    Started to snow later in the afternoon.

Weather Observations for November 19, 2017 taken at 06:00 Hours.

2180 meters    -5, Winds were 40-80 KPH S   --Whistler Peak
1835 meters    -4, Winds were 25-55 KPH SE --Roundhouse
1660 meters    -2, 22 cm of new, Base176 cm --Pig Alley
  660 meters   +1, Valley Temp, Max Temp Yesterday was +3.0, 3.6 mm of Precip recorded yest



FORECAST:

A cold front will push through today in a Northwesterly flow aloft. The freezing level will hover in the 1000 meter range, possible spike similar to yesterday to 1500 M and we can expect high alpine winds. Monday will see unsettled weather with the FL hovering in the 1200 meter range. A warm front will slowly move into the area on Tuesday with mostly overcast conditions with the brunt of the precipitation arriving Tuesday night. The FL will also slowly rise as the day progress reaching the top of the local peaks by Tuesday night. Wednesday is looking wet warm and windy. FL could top out at 2800 meters. Guesstimates: 40-60 cm by Monday morning, Trace by Tuesday morning, 150-200 mm of rain by Thursday morning.


    Looks fairly juicy for today.

    Cold front pushing South.

    Unsettled for Monday.

    Warm front pushes in on Tuesday. Brunt of the precip arrives Tuesday night.

      Looking warm, wet, & windy on Wednesday.


    Flow into next week!



OBSERVATIONS & INFORMATION:

    With the storm tomorrow pay attention and ski with a partner.

    Lots of people going for a tour, be sure you are not going through an avalanche closure!!

    Big picture Saturday afternoon.

    By days end it was overcast & snowing on Saturday.


From South Coast Touring:

Simon Thomson
November 18 at 10:55pm
Up the Duff today, here's some observations to pass on: 

Skied N aspects from 2000m to 1700m. 
Mostly shin deep trail breaking, foot pen to the crotch.  
About 50cm at the road. Great ski conditions, limited wind slab felt, all in all just unconsolidated low density snow. Minor cracking in isolated areas but no propagation. 
No avalanches seen or triggered... limited obs. 

Quick pit to ground showed no significant results on compression test. HS 160cm @ 1800m. Progressive resistances in top 110cm. Laminated crust 50cm to ground with small facets above and below. Moist snow bottom 10cm. 



ARTICLES:

3 skiers involved in an avalanche in the Lake Tahoe Area: Hourglass Bowl

Update on the avalanche in Afghanistan: 13 Killed

Fostering a New Wave of Women's Avalanche Clinics: Powder

Snowfall warning in effect: Environment Canada

Avalanche closure on Highway 16: Terrace, B.C.

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