| OCR Text |
Show SECTION 5-- AVALANCHE OBSERVATIONS Little hardware is required to observe avalanches. The observer's sharp eye, an alert mind, and pencil and notebook ( A35) are the main necessities. A good pair of binoculars is a very useful accessory. These are essential in a large area where size, type, and fracture line height of distance avalanches must be recorded. If a particularly good ( and readily accessible) vantage point exists for scanning an extensive area, a variable- power spotting telescope may prove useful. It should have permanent provision for tripod or other fixed mount. Many ski area administrators will find frequent use for optical aids other than to observe avalanches. Check of closure signs, search for missing skiers, or routine inspection of snow conditions and cornice formation all profit by the use of binoculars or a telescope. Many quality instruments are available on the market; we make no specific recommendation other than to suggest that a 7_ or 8- power binocular will be the most useful. The wide- field models are the most versatile. Because most viewing will be done in bright light, the large, heavy binoculars with large objective lenses are not necessary. Compact models easily carried by a man on skis are preferred. Government agencies often can find good instruments through GSA surplus lists. It is difficult to record all the pertinent features on an avalanche unless some systematic approach is taken. In recent years a form has been developed to facilitate reporting avalanches and avalanche control action on Class A ski areas ( Figure 10). The most important data are the name of the avalanche and the date and time of occurrence. Most active avalanche paths near populated areas have names. Use the local name whenever it is known. When several names are used for the same avalanche, a choice must be made and the other names avoided. Unnamed paths should be named or numbered for future reference. A photographic record of avalanche paths with appropriate names is the best way of assuring proper identification. The date and time required refer to when the avalanche ran and not when the notes are made. If exact date and time are not known, an estimate must be made and recorded as such. The standard avalanche classification as used in the United States covers avalanche type, trigger, size, sliding surface and air blast, in that order. Avalanche type is designated as soft slab ( SS) , hard slab ( HS), or loose ( L). These abbreviations may be preceded by a D to indicate damp, or W to indicate wet snow conditions. Loose snow avalanches originate from a point and spread outward and 29 |
