Extended Abstract (136K)13B.5
Non-convective high wind events: a climatology for the Great Lakes region
John A. Knox, Univ. of Georgia, Athens, GA; and M. C. Lacke, J. D. Frye, A. E. Stewart, J. D. Durkee, C. M. Fuhrmann, and S. M. Dillingham
A 44-year climatology of non-convective high wind events has been created using hourly wind data for 38 first-order weather stations across the Great Lakes region spanning the months of November through April. The data were analyzed in terms of the two National Weather Service (NWS) criteria for a high wind watch or warning: sustained winds of at least 18 m/s (40 mph) for at least one hour or a wind gust of at least 26 m/s (58 mph) for any duration. Inconsistencies in anemometer height during the period of the climatology were examined and found not to introduce significant bias.
Our results indicate a pronounced southwest quadrant directional preference for non-convective high winds in this region. Between 70% and 76% of all occurrences that satisfied the NWS high wind criteria were associated with wind directions from 180 through 270 degrees. Within the southwest quadrant, the west-southwest direction is preferred, with 14–35% of all high wind events coming from this particular compass heading. This directional preference is borne out in five out of six stations with high occurrences of cold-season high wind events (Buffalo, NY; Dayton, OH; Lansing, MI; Moline, IL; Springfield, IL); the one station without this preference (Rochester, MN) is located on the cold side of the typical wintertime mid-latitude cyclone storm track.
Given the geographic spread of these stations, a non-topographic cause for the directional preference is indicated. The connection between non-convective high wind events and low pressure systems found in this climatology and in case studies suggests that mid-latitude cyclone dynamics may be a possible cause of the directional preference. The implications of this research for a better understanding and prediction of non-convective high wind events will be discussed.
Session 13B, Cool Season and Non-Convective Severe Weather
Wednesday, 29 October 2008, 1:30 PM-3:00 PM, South Ballroom
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