28 Feb 2021

February 28, 2021

     YESTERDAY:

     Sproatt Mountain early Saturday am.

     It was a busy morning.

      Cowboy Ridge.

      Rainbow Mountain.

      Overcast to the Southwest.

      Looking North East in the am.

      There were a lot of people playing on the steeps Saturday.


     Overcast to the South.

     Cloudier as the morning progressed.

      There were some blue patches in the pm.

      Saturday February 28, 2021. 14:00 Hrs. -6 with a 15-35 KPH SSW wind. +2 in the valley.

        Satellite image from the same timeframe as above image.

     Big picture Saturday afternoon.


     Overcast in the afternoon.


     Thicker clouds arrived  later in the afternoon.


Weather Observations for February 28, 2021 taken at 06:00 Hours.

2240 meters      -7, Winds were 15-25 KPH S--Horstman Hut
2180 meters      -7, Winds were 40-50 KPH S--Whistler Peak
1860 meters      -4, Winds were 15-25 KPH SE --Rendezvous 
1835 meters      -4, Winds were 20-35 KPH S--Round House
1650 meters      -3,  2 cm in 12 Hrs, 2 cm in 24 Hrs, Base 252 cm --Pig Alley
1570 meters      -4,  1 cm in 12 Hrs, 1 cm in 24 Hrs, Base 183 cm--Catskinner
  660 meters      -1, Valley Temp, Max temp Yesterday was +3.3, 0.0 mm of precip yesterday.


      As of 07:00 Hrs this am we have overcast skies and unlimited visibility.


FORECAST:

A weak warm front will push through later today in a North Westerly flow aloft. Cloudy this am with some periods of light snow developing later this afternoon. The FL will likely spike at around 1200 meters and hover in that range with a drop back down to 800 meters by Tuesday. Periods of light snow for Monday with a warm overcast day and Westerly flow aloft.. Drying out Monday night into Tuesday morning before another weak cold front arrives Tuesday morning into Wednesday. A more potent front should arrive Thursday with more precip expected Friday and Saturday. Guesstimates: Trace-3 cm by Monday am, 2-6 cm by Tuesday am, 2-6 cm by Wednesday am, 1-3 cm by Thursday am. 


      GOES IR image from this am.


      Weak warm front for today with rising FL.





     Northerly flow aloft.

      Weak cold front with warmer temps for Monday.





        Low in the Gulf of Alaska will send fronts our way into the weekend. Weak one on Tuesday.



     AVALANCHE ACTIVITY:

     An avalanche has killed a snowmobiler on Tiger Peak, Idaho. Article below.                  Net Pic

      Old slab in Whistler Bowl.


     Cornice release on Whistler.


     That debris would hurt you.

      Dry loose across the valley, likely from Friday.

      Old bomb Hole.

     Old avalanche and cornice debris in Glacier Bowl.


     No new avalanches observed on Whistler. Sz 2 cornice release.

      No new avalanches observed on Blackcomb. Some pinwheeling on steep rocky solar terrain.

      Even a small roof avalanche can cause some damage.



From Sea to Sky avalanche advisory:

Avalanche Summary

Reports from Thursday and Friday show:

  • Evidence of the previous natural storm cycle up to size 3 on north to east aspects 1500 to 2000 m.
  • Good propagation in explosive triggered storm slabs to size 2 (Thursday).
  • Storm/wind slabs have been reactive to human triggers around treeline to size 1.
  • Cornices have been very reactive to explosives as well as remote human triggers, size 2-2.5.

Going forward:

  • Wind loading patterns will likely reverse with northwest winds, forming reactive wind slabs in new features.

Snowpack Summary

20 cm of recent snow overlies a variety of old surfaces including facets, spotty surface hoar in wind sheltered areas around treeline, a sun crust on steep solar aspects and a rain crust below 1500 m. Upper level wind, having recently shifted northwest is likely transporting the recent snow into wind slabs in a reverse-loading pattern in exposed features at upper elevations. Older wind slabs formed by previous southwest winds may also remain reactive to human triggers.

Another weak layer buried in mid-February is composed of a crust, facets or spotty surface hoar depending on elevation/aspect, and is now down 50-80 cm. There have been no recent avalanches reported on this layer. Large triggers, such as an avalanche in motion, cornice fall, or intense loading from snow, wind and/or a rapid rise in temperature could awaken these deeper weak layers.

The mid and lower snowpack is well settled and strong in most areas.


      INFORMATION & OBSERVATIONS:

     Pay attention to the signs.

     Can you find the roof of the Claire and Kees Hut?

     Tracks on Cowboy Ridge. Still evidence of old crown lines.

      Nice turns and conditions in Banana Chute Saturday.                                             Andre Ike Image

      Enjoying the turns in Fissile.                                                                                   Andre Ike Image



     Backcountry has been busy.


     Sending it down the Coffin.

     The wind can certainly make some nice shapes out of the snow.


      With cornice control this is a good sign to pay attention too.

      Cornice debris in Glacier Bowl on Whistler.

     Perfect Cord.

     Its slowly creeping, looks heavy.

     Nice day in the park.


FROM SEA TO SKY MIN REPORTS:

Stadium Glacier: Feb 27, 2021

Mount Mulligan: Feb 27, 2021



VIDEOS:

Sherman Peak Avalanche Accident: Feb 20, 2021

Weak Layer test: Colorado


ARTICLES:

A snowmobiler has been killed in an avalanche on Tiger Peak: Idaho

'Large and destructive' human triggered avalanches expected in Interior Ranges: B.C.

Risky Positioning-Social Aspirations and risk taking behaviour in avalanche terrain: Powder Canada

A note on how we address avalanche fatalities: Teton Gravity Research

Final report on Ruby Mountain avalanche fatality (snowmobiler): CAIC

Final report on Pumphouse Lake avalanche fatality (snowmobiler): CAIC

Snow avalanche occurs in J-K's near army convoy: Kashmir


         Submit your best avalanche photo for a pair of  Goggles Feb 1-28, 2021. Sea to Sky Area.

                                                    Thanks to Volkl Canada for sponsoring.

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