P 1 . 57 Goes Wmsi – Progress and Developments

A multi-parameter index has been developed to assess the magnitude of convective downbursts associated with heavy precipitation-producing, deep convective storm systems that occur over the central and eastern continental United States. The Wet Microburst Severity Index (WMSI) is composed of relevant parameters that represent the simultaneous physical processes of convective updraft development and downburst generation, incorporating convective available potential energy (CAPE) and the vertical equivalent potential temperature (θe) difference between the surface and the midtroposphere (Pryor and Ellrod 2004). The WMSI algorithm is given as the following expression: WMSI = (CAPE)(∆ θe)/1000. ∆ θe = θemax θemin, where θemax refers to the maximum value of θe at the surface and θemin refers to the minimum value of theta-e in the midlevels of the troposphere (Atkins and Wakimoto 1991) . The Geostationary Operational Environmental Satellite (GOES) WMSI product, as displayed in Figure 1, ingests atmospheric sounding data (i.e., temperature and dew point) provided by satellite retrievals. The WMSI algorithm is designed for use during the warm season, specifically from 1 June to 30 September. Pryor and Ellrod (2004) found that there exists a statistically significant correlation between GOES WMSI and the magnitude of observed surface wind gusts for both daytime (r = 0.66) and nighttime (r = 0.64) events during the warm season.