  This paper presents a new application of brightness temperature difference
(BTD) between Geostationary Operational Environmental Satellite (GOES) imager
channels 3 and 4. It has been found recently 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. Case studies demonstrating effective
operational use of this image product are presented for two significant marine
transportation accidents as well as a severe downburst event over the
Washington, DC metropolitan area in April 2010.
