Recent developments in microburst nowcasting using GOES

Abstract

Recent testing and validation have found that the Geostationary Operational Environmental Satellite (GOES) microburst products are effective in the assessment and short-term forecasting of downburst potential and associated wind gust magnitude. Two products, the GOES sounder Microburst Windspeed Potential Index (MWPI) and a new two-channel GOES imager brightness temperature difference (BTD) product have demonstrated capability in downburst potential assessment. The MWPI, a diagnostic nowcasting product, is designed to infer attributes of a favorable microburst environment: large CAPE and a convective mixed layer with a steep temperature lapse rate and low relative humidity in the surface layer. These conditions foster intense convective downdrafts due to evaporational cooling as precipitation descends in the sub-cloud layer. More recently, a new application of the brightness temperature difference (BTD) between GOES imager channels 3 and 4 has been developed. It has been found that the BTD between GOES infrared channel 3 (water vapor) and channel 4 (thermal infrared) can highlight regions where severe outflow wind generation (i.e. downbursts, microbursts) is likely due to the channeling of dry mid-tropospheric air into the precipitation core of a deep, moist convective storm. This paper provides an updated assessment of the MWPI and new GOES BTD algorithm, presents case studies demonstrating effective operational use of the microburst products, and presents validation results for the 2010 convective season over the United States Great Plains and Atlantic Coast regions.