The analytic expression relating GOES-E/W channel 3 water-vapor radiance to relative humidity is used along with upper-troposphere temperature observations to derive a high horizontal resolution brightness temperature product that correlates well with measured specific humidity. Moisture information in raw water-vapor images is obscured by strong horizontal temperature gradients in the upper troposphere. This information is exposed in the derived product. Our results illustrate that the ability to remotely sense and resolve differences in water-vapor content increases with atmospheric dryness. ¿ 1999 American Geophysical Union