OCR Text |
Show Notes on Major Storm Comparison Chart #1 - Measured in inches. 2. #2 - P or Pwd. means powder snow. 3. #3 ~ Measured in inches on a 2^-hour basis. k. Cr means crust. - Damp/Pwd. means damp snow over powder snow and so on. P alone or Pwd means powder snow. P & P means powder and pellet snow. G means granular snow. 5. #5 - A ratio. The figure indicates inches of water per inch of snow. 6. #6 - A ratio. The figure indicates inches of snowfall per hour. 7. #7 - A ratio. The figure is the result of dividing the storm duration in hours into the number of hours wind force was at critical levels. 8. #S - Detailed information on wind direction in terms of hours is not available. 9. #9 ~ Where used, the arrow indicates the direction of temperature development, 10. #10 - A ratio. The figure indicates inches of settlement per inch of snowfall on a 2U-hour basis. 11. Recap. The upper figure in each box is the total number of avalanche factors operating. The lower figures refer to the individual avalanche factors. Plus means favorable to avalanches. Minus means unfavorable to avalanches. 0 means negative effect. 12. Duration - measured in hours. 13. Avalanche cycle. The first column indicates storm duration in hours when avalanche cycle began. The second column indicates inches of snowfall when avalanche cycle began. Special storms. The storms in this group do not fit into any regular pattern. They are included to remind the observer that analysis of recognized avalanche factors offers him a logical background for his reasoning, not a yardstick he can apply with blind faith and mechanical precision. Many of the facts revealed by the preceding charts are not exactly news to the experienced snow observer, but it has not previously been possible to demonstrate them in a logical manner. This method of analyzing snow behaviour is practical rather than technical, based on experience rather than experiment. It has its limitations, like any other method. The principal one is lack of sufficient data. This is a matter both of volume and of detail. A hundred storms compared would yield much more accurate information than forty and will -36- |