This is the Annual Report of the Colorado Avalanche Information Center (CAIC) for the winter of 1997-1998. It describes the operations of the CAIC and the important events of the winter season. This annual report contains the executive summary; Funding and budget; operations; weather and avalanche synopsis; detailed winter summary; information acquisition; dissemination of forecasts, public education; forecasting for highways. 36 pages. 3 figures. 6 tables. Digital file available as a download. IS-46D
Excerpted from the report:
The Colorado Avalanche Information Center (CAIC) completed its 15th year as a program of the State of Colorado. For the first time ever technology allowed climate researchers to detect the El Nino in November, 1996, and predict its magnitude by June, 1997. Researchers originally felt this winter would be the biggest El Nino this century. Review of snowfall records showed great variability during previous El Nino winters, though there was a bias toward a drier winter. One strong trend that appeared from the dry winters was the early and middle winter (November through February) was very dry, but the spring months of March and April were snowy. This would mean a thin, unstable snow cover with lots of depth hoar for most of the winter to be followed by springtime deep snows and a few big avalanches. That is exactly what happened!
Avalanche events of 1997-98: The El Nino winter produced snowfall that was slightly below normal (87% to 106%) with many days of very light snow and few large storms. The mountain snowpack was shallower and weaker than normal in the first 4 months of winter. A total of 2,958 avalanches was reported to the Center (40% above the average of 2,110). Though there were more avalanches, the average size was smaller and there were very few large, destructive avalanches. Avalanche Warnings were posted on 21 days (12 below normal). There were six avalanche deaths (one above normal). Property damage was $150,000 (near normal).