Monday, 7 January 2013
Exhibit Hall 3 (Austin Convention Center)
Winter storms in the southern United States have been associated with significant impacts to infrastructure and economy. During the years 2000-2009, there were at least 7 major winter storms over the Southern Plains, all of which received federal disaster declarations. National climatological studies of winter storms, including snowstorms and ice storms, have been developed but there remains a dearth of regional climatologies of winter storm distribution and frequency. In addition, synoptic and mesoscale mechanisms that support the evolution and maintenance of winter weather and precipitation phase type are often regionally specific. In this study, we use the National Climatic Data Center Storm event database and local climate summaries to construct a winter weather case study database for 1993-2011. We use this information first to create a regional climatology of freezing precipitation (ice, sleet) and frozen precipitation (snow) over the Southern Plains, which we define as encompassing the domain between 32-38N, and 92-102W. Next, we use principal component and composite analysis to extract common synoptic patterns during mixed phase winter weather with an emphasis on understanding distinctions between the evolutions of ice storm/freezing precipitation, versus snowstorm events. We evaluate the characteristic thermal profiles, surface pressure, atmospheric dynamics and composite evolution for each synoptic pattern; thus creating a pattern-recognition based reference to aid the forecaster. We then discuss the role of large-scale climate; specifically the impact of Gulf of Mexico sea surface temperatures, on moderating thermal profiles associated with freezing precipitation. Future work, including our planned modeling studies will also be briefly discussed.
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