Medicine Bow Nordic Ski Patrol
Patrol Log: Saturday, February 2, 2008:
R. Howell and J. Pohl
On Saturday
Feb. 2 Joe Pohl and Bob Howell skied the Libby Creek loop from Green
Rock to the hairpin turn at its west end, then NW up the drainage to
the headwaters of Sally Creek, then back Sally Creek to Snowy Range
Lodge then Green Rock. We met several other groups on skies and
snowshoes. The snow conditions were very good, with approximately
10 inches of new powder in the last day. The temperature was 20F,
the wind was light, and it was clear in the morning with light snow
developing by late afternoon. The snow depth was 46 inches at the
snow stake near the start of the trail.
We dug a snow pit at NAD27 13T 0397769 4576911, elevation approximately
9980 ft on an open slope south of the Libby Creek trail, at the top of
the slope dropping down into the Libby Creek valley. The slope
was 22 degrees, facing 152 degrees (SSE). The surface temperature
in the shade was -9C. The pit showed the following snow pack
structure.
# Height
Temp Comments Hardness
Snow grain structure
(cm) (C)
----126----------------------------------------------------------------------
6
120 -11.5 new powder
fist 0.4 mm F2 stellar
crystals
110 -10.0
----102----------------------------------------------------------------------
5
100
-9.5
3 fingers 0.3 mm F5 slightly
rounded
----
95----------------------------------------------------------------------
4
90 -8.0
80
-7.0
2 fingers 0.3 mm slightly rounded crystals
-----76----------------------------------------------------------------------
70 -6.0
3
60
-5.5
1 finger 0.5 mm metamorphosed F5 spatial dendrites
-----54----------------------------------------------------------------------
2
50
-4.5
pencil 0.8 mm highly metamorphosed F3 --
almost graupel like
-----41----------------------------------------------------------------------
40
-4.0
4 finger 1.5 mm faceted 1
30 -2.5 depth hoar
20 -2.0
10
-1.0
1 finger 2.5 - 3 mm faceted
-----0
-1.0 --------------------------------------------------------------
Note -- in the depth hoar the grain size increases smoothly towards the
bottom,
The hardness also increases smoothly towards the bottom.
Shovel
shear test. Working down through the pack
Slight
force for failure at top of layer 5 (102 cm height) -- i.e. failure of
the new powder
Moderate
force for failure near the middle of layer 4 (86 cm height)
Moderate
force for failure at top of the depth hoar (41 cm) with the material
above (up to 86 cm) sliding as one large block
In the Rutschblock test:
It required multiple hard jumps to produce a shear near 65 cm, in the
middle of layer 3. The failure surface
eventually produced was a smooth sliding surface.
The car counts were as follows.
------ 10:00
AM -------
with without
trailers trailers
Corner
Mountain Lot
0 2
Little
Laramie
Lot
0 2
Ski Area to
Cattleguard
48 1
Cattleguard
to Turnaround 21 3
Green Rock
Picnic Gnd. Lot 0 20
Road above
Turnaround
20 3
Total
89 31
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Patroller Calendar
Page last modified February 4, 2008
Comments/Additions/Corrections to hamannj@tribcsp.com