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Show THE ALTA SNOW STUDIES ANNEX A. ALTA AVALANCHE HAZARD GUIDE The following instructions are intended particularly for the guidance of administrators new to the area. They may also serve as a suggested model for setting up similar instructions in any alpine ski area. The table of avalanche conditions is "based on the Major Storm Comparison Chart with the addition of the factors of visibility and field testing. These two factors must confirm the estimates an observer makes on current hazard conditions. General Instructions 1. The following table of avalanche hazard conditions and protective action is not a complete set of rules telling you what to do under any and all circumstances. You are expected to use your judgment, which will improve with practice and familiarity. 2. The table sets up a series of representative conditions definitely favorable or definitely unfavorable to avalanches of dangerous size. Conditions in the field will seldom fit the pattern exactly. The most important items to keep track of are (l) the new depth, (2) rate of fall, and (3) wind force and direction combination. 3. The most difficult hazard to forecast is the prolonged storm with many fluctuations in violence. Field testing and observation will be your most important guides in borderline cases. When in doubt, play it safe until you find out. U. Remember the 2-hour allowance for making safety measures effective. The critical snow depths in Column 12 of the table are averages, not exact dividing lines. Unless otherwise indicated in Column 13, they are the points beyond which trouble may be expected at any time unless conditions improve. 5. Read the explanatory notes before attempting to use the guide. 6. Remember that you are forecasting hazard, not avalanches themselves. If conditions are dangerous, it makes no difference v/hether slides actually occur or not. To say that there was no hazard because no dangerous avalanche occurred is like saying there was no hazard in driving around a curve on the wrong side of the road because you didn't meet anybody. The standards of avalanche hazard set up in the guide are based on fact, not opinion. The Major Storm Comparison Chart is your reference. 7. When apparent unsafe conditions have developed during an overnight storm or are developing as a result of a fresh daytime storm, public safety demands that preventive action be taken to protect life and property. |