S25 Extreme Temperatures in Southeast Alaska

Sunday, 23 January 2011
Richard, C. Lam, Bay Area Air Quality Management District, San Francisco, CA

The Juneau Forecast Office, responsible for producing weather forecast products for Southeast Alaska, have to forecast extreme temperature events. By learning more about the synoptic patterns associated with these anomalous events, forecast confidence can be enhanced. This study focuses on extreme temperatures events (i.e. Summer High, Winter High, and Winter Low) for zones 17 to 28 in Southeast AK. The top 20 events for each category are utilized to generate composite averages and anomalies. Weather patterns, associated with these extreme temperature events are plotted and analyzed. Evaluation of several cases demonstrate that to have extreme high summer temperatures in the Alaska Panhandle, there needs to be an anomalously strong surface high in the Yukon Territory in order to advect warmer and drier air from the Interior into the coastal region. On the other hand, the same high pressure may bring in anomalously cold air from the Arctic region to Southeast Alaska during winter months. In addition, the variability associated with these anomalous weather events are also studied. Besides, precursors to these extreme temperature events may occur two weeks prior to event onsets.
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