WMOD00219

• Applicant: Colorado State University
• Project Name: Research in the Park Range Area in Colorado
• Date: 12/4/1979
• Weather Modification - Doc Type: License & Permits

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Wl>180-2

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ATTACHMENT A

SUSPENSION GUIDANCE FOR AVALANCHE AND SEVERE STORM

1979-80

A. Snowpack less than 90% of Normal
Location 24 Hr. Max. And I Or Previous 10 Day
Precip. Fest. (H2O) Accumulation
Berthoud Pass 1.50 3.50
Vail 2.25 4.25
E1kton 2.25 4.25

B. Snowpack 90 to 119% of Nomal
Berthoud Pass 1.25
Vail 1. 75
Elkton 1. 75
C. Snowpack 120 to 149% of Nomal
Berthoud Pass .6
Vail .9
E1kton .9
D. Snowpack greater than 150% of Nomal
Berthoud Pass .4
Vail .7
Elkton .7

2.75
3.50
3.50

1. 75
2.25
2.25

1. 25
1. 75
1. 75

E. Additional consideration will be given to wind in each and every case. The
most hazardous wind speeds range from 30 Kts. to 50 Kts. To assess ava-
lanche potential, use the following:
Additional Fisk Factor: Low MDT High Extreme
10,000 Ft. Wind Speed 15 Kts. 25 Kts. 35 Kts. 45 Kts.
12,000 Ft. Wind Speed 20 30 40 50
14,000 Ft. Io/ind Speed 25 35 45 55

F.

A second factor to consider is the condition
If a prolonged sunny and warm period preceeds
a difficult time adhering to the old surface.
use the following:

Rule of Thumb for slides:

of the surface of the old snow.
a storm, the new snow will have
To assess avalanche potential,

Snow/Water
20/1
15/1
12/1
10/1
8/1

Ratio
18"
IS"
12"
10"
8"

Will cause sliding.
This requires a build-up proper weight.

The above amounts need to be correlated with wind.
This guidance does not apply to thawing avalanches, but should certainly enter
into the Hazard Evaluation when a precipitation episode follows thawing
conditions.