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Avalanche Assessment Data Sheet

Archived Reports   (Opens a PDF file)

Click Here for current Temple Basin Avalanche Assessment information

Assessment Date & Time: 18/08/2018 1234hrs
Observer Name/s: GK + GK
Assessment Location: Upper Otira Valley - TL Flank (E1479217 N5248586)   Altitude (m): 1540m
Slope Angle (xº) & Aspect (1-360º Mag.): 37º, 270º

Current Weather Conditions: Clear and fine
Air Temperature (ºC): 7.1ºC
Wind Direction / Strength (1-360º Mag. / Kmph): 0º @ 0km/h
Hygrometer RH (%): 32% Stable
Uncorrected Barometer (mb): 924mb Falling

Previous Activity: Wet snow avalanches to Class 3-4. Storm-slab release at 1800m on East aspect, crown=1m, width=150m.
Current Activity: Face deload sluffs Class 1 - 2 on northern aspects starting at 1800-1900m. Considerable radiation snowballing.

Snow Crystal Descriptor Codes

ABCDEFGHI
New snow Partly decomposed snow Small rounds Faceted grains Rounding facets Melt freeze crust Graupel Ice layer Needles
JKLMNOPQR
Columns Plates Melt freeze/wet Clustered grains Polycrystals Slush Rounded grains Depth hoar Surface hoar

Hardness Descriptor Codes (Hand Test)

VSSMHVHHI
Very soft - Fist Soft - Four fingers Medium hard - One finger Very hard - Pencil Hard - Knife Ice - Impenetrable

Snow Structure Data

Temp
Gradient
Surface10cm 20cm30cm40cm 50cm60cm70cm 80cm90cm100cm110cm120cm130cm
0.3ºC -0.3ºC 0.0ºC 0.3ºC 0.3ºC 0.2ºC 0.2ºC 0.1ºC 0.1ºC 0.1ºC 0.1ºC 0.1ºC 0.1ºC 0.0ºC
140cm150cm 160cm170cm180cm 190cm200cm210cm 220cm230cm240cm250cm260cm270cm
0.0ºC 0.1ºC 0.1ºC 0.1ºC 0.0ºC                  
Layer Thickness
cm
(base)
Hardness
(Hand Test)
Xtal.
Size (mm)
Xtal.
Shape
Internal
Bond
Column
Shear
Force
ECT
Shear
Force
Density
kg/m3
Water
Equiv.
Notes
1 12 S 0.2 A,B Good 280 34mm Dry snow - rounded
2 1.0
(13)
MH 0.3-0.4 C OK CT0 300 3mm Rain crust
3 7.0
(20)
MH 0.3 C OK CT0 460 32mm  
4 6.0
(26)
MH 0.2 C OK 460 28mm  
5 2.0
(28)
MH 0.3 C Poor 420 8mm Melt/freeze crust
6 4.0
(32)
S 0.8-1.0 G OK 400 16mm  
7 3.0
(35)
S 1.0 C Poor 480 14mm  
8 15.0
(50)
VS 1.2 C Good CT0 360 54mm  
9 39.0
(89)
S 1.0 C OK CT4 500 195mm Free water present, poor sintered bonds
10 19.0
(108)
MH 0.8 C OK CT3 528 100mm Free water present
11 17.0
(125)
MH 1.0 C OK CT1 480 82mm Free water present
12 17.0
(142)
S 0.8 C Good 540 92mm Impermeable layer
13 38.0
(180)
MH 1.5-2.0 L Poor 480 182mm Free water present, wet snow - sugary, 120cm to rock
Pack Statistics
Snowpack Depth: 300.0cm
Snowpack Weight: Indeterminate!

Pack Analysis :
Isothermic snowpack containing two crusts and a deep impermeable layer. A considerable amount of free water is present throughout lower snow-pack. Surface snow is a soft-slab formation.

Column Shear Test :
2 CT0 shears in upper pack at 13 & 20cm. Multiple easy shears in lower pack below 50cm. Compression of upper layers did strengthen them slightly, but they still failed on isolation.

Extended Column Shear Test :
Only partially carried out, but basically results of the shear test were replicated within the top layering.

Foot Pressure Tests :
Top 20cm would fail about 60cm from edge.

Rutschblock Test :
Not performed.

Activity Assessment :
Storm-slab is definitely present on E & W aspects above 1500m. At lower altitudes it is about 20cm, at 1800m it appears to be 1m+. It would be reactive in steeper terrain (40º+), and on convex rolls & near edges. Face deloads on solar aspects were also very active, with multiple Class 1 sluffs, but the ocassional Class 2-2.5 did roll off, initiated as a point release from higher altitude (1800m -1900m). Conditions were best described as poor, and should be avoided.

Current Assessment :
High Alpine (1800m+) - Considerable
Alpine (1200m - 1800m) - Moderate
Sub-Alpine (Below 1200m) - No Rating
 

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