The Advanced Baseline Sounder (ABS), now being referred to as the HES (Hyperspectral Environmental Sensor), is being designed for future Geostationary Operational Environmental Satellites (starting with GOES-R in 2012). ABS will have thousands of channels with widths on the order of single wavenumbers (approximately 0.5 cm**-1), while the current GOES Sounder has only 18 bands with widths on the order of tens of wavenumbers. In the absence of clouds, the ABS has the capability to produce a three-dimensional depiction of temperature and moisture with better vertical resolution (approximately 1 km) and temporal resolution (hourly full disk soundings) while maintaining the horizontal resolution (approximately 10 km). The ABS will be capable of frequently observing: atmospheric vertical temperature and moisture profiles, the structure of clouds, inferring the presence and transport of key atmospheric constituents, and deriving surface properties (surface pressure, surface skin temperature and infrared spectral surface emissivity). These observations will be important in addressing the science questions related to the structure and dynamics of atmospheric systems, atmospheric chemistry, and transportation of constituents, and diurnal variations and short-term changes in the atmosphere and at the surface. The observations from the ABS will also provide the operational data required for improved fine-scale modeling and forecasting of significant weather related to convective systems and cyclonic storms. Simulations with MM5 cube data have been carried out to demonstrate the capability of ABS on high temporal, high spatial and high vertical resolution atmospheric, cloud and surface products with high accuracy. Recent hyperspectral aircraft (NASTI/SHIS) and space-based (AIRS) sounder measurements will also be used for the ABS study.