85th AMS Annual Meeting

Sunday, 9 January 2005
Mesoanalysis of Bow Echo Environments during BAMEX
Amber E. Reynolds, NCAR, State College, PA
One of the more significant forms of mesoscale convective organization is the bow echo. Although bow-shaped convective lines are relatively small in scale (20 120 km long), they can produce damaging straight-line winds over periods of several hours across swaths of several hundred kilometers. Bow echoes represent a challenge for operational forecasting and warning of severe weather. It is difficult to predict the severity of these systems, which often results in false severe weather warnings issued to the public. The environments of bow echoes sampled on June 10, June 24, June 25/26, and July 4/5, 2003 during the Bow Echo and Mesoscale Convective Vortex Experiment (BAMEX) were analyzed to determine differences associated with bow echoes that produce localized vs. widespread straight-line wind damage. Surface-based, Most Unstable, and Mixed Layer Convective Available Potential Energy (CAPE) and Convective Inhibition (CIN) were computed from environmental soundings. Bulk wind shear was also calculated for surface to 3 km (low-level) and surface to 6 km (deep layer) intervals for the four cases. In addition, an analysis of bow echo maintenance was performed by comparing the velocity representing the strength of the cold pool versus ambient low-level wind shear. The results of this investigation indicated that the amount of CAPE and CIN can vary greatly in the environments preceding bow echoes. In addition, there was no significant difference in the amount of low-level or deep layer wind shear to contrast localized versus widespread straight-line wind damage cases. The results of this investigation will be useful to other scientists who are investigating different aspects of these four cases.

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