Investigating specific event types in the western U.S utilizing standardized anomalies

Standardized anomalies were computed from the global re-analysis data for the period of 1 January 1948 through 31 December 2006 for the western United States. The computations were done in 6-hour increments with anomalies computed for heights, temperatures, winds, specific humidity at mandatory levels and surface based variables such as mean sea level pressure and precipitable water. The base climatology for the means and standard deviations was computed for the period 30 year period of 1971-2000.

Following the methodology presented by Hart and Grumm (2001), the western United States events are ranked objectively based upon their standardized anomalies method of pressure weighted anomalies by variable. The degree of rarity for an event is determined by the departure of these fields from climatology.

Specific event types are investigated by examining historical events and their associated anomalies. Event types investigated include Pacific Northwest windstorms, coastal heavy rain events and heat waves. The anomalies associated with ten historical storms in each event type will be summarized. Historical events included in this examination include the Columbus Day storm of 1962, the 1997 California New Year's Day flood event, and the California heat wave of 2006.