ANCHORAGE WINDSTORM OF 1 DECEMBER 1992

On 1 December 1992 a strong downslope windstorm with an atypical damag e pattern hit Anchorage. Downslope windstorms are common in Anchorage from September through April. Typically damaging winds from these stor ms are confined to the foothills of the Chugach Mountains and east Anc horage within 5 km of the edge of the foothills. In the 1 December sto rm, moderate wind damage occurred across the entire city in areas wher e wind damage is a rarity during downslope windstorms. Anchorage forec asters use an empirically derived automated technique to forecast down slope windstorms. The technique works very well. It is the purpose of this study to add to this technique so that atypical storms like the 1 December storm can be detected in advance. Historical records were se arched and two storms with similar atypical damage patterns were found . In this study the 1 December windstorm is described, the two histori cal storms with similar atypical damage patterns are described, and a forecast tool is devised using a combination of characteristics common to the three storms that is hopefully unique. A by-product of this st udy is a synoptic-scale tool for forecasting the onset of maximum wind s for the majority of Anchorage downslope windstorms.