Precipitation is a critical forcing in hydrologic models. Point measurements (rain gauges) often are not representative of the amount of precipitation falling over a large area such as the Southern Great Plains '97 Experiment (SGP97) study area. This is particularly true in summer, when the trigger for precipitation is local convection, rather than large-scale synoptic systems. Radar return, such as that from the NOAA WSR-88D weather radars, provides much better spatial coverage, but is not a direct measure of precipitation. Instead, an estimate of precipitation must be made from algorithms that relate radar reflectivity to rainfall rate. The Arkansas-Red Basin River Forecast Center (ABRFC) provides a routine data product that combines WSR-88D radar-based precipitation estimates with over 500 rain gauge measurements. This is an hourly product with 4-km resolution. More information is available on the web (http://www.abrfc.noaa.gov/pcpnpage.html).
Hourly precipitation estimates have been extracted from the ABRFC 4-km grid for a gridded area that encompasses the SGP97 area. Precipitation patterns in this gridded area are compared with satellite images for the SGP97 period (6/18/97 - 7/18/97). Vertical profiles of cloud radar reflectivity from the Atmospheric Radiation Measurement (ARM) Program Central Facility are compared with satellite and precipitation patterns to study further the cloud/ precipitation relations. Measurements from ARM rain gauges are used as another check of the ABRFC precipitation estimates. Note that precipitation measurements from the dense Oklahoma Mesonet are included already in the 500 rain gauges used to adjust the radar estimates, and thus cannot be used for further validation. ABRFC precipitation estimates and their comparison with cloud and precipitation observations are presented and discussed. Precipitation estimates and cloud patterns are consistent. The SGP97 period is characterized by several mesoscale precipitation events that more frequently cover the northern half than the southern half of the SGP97 area. Precipitation observations show slightly more intense rainfall in the northern half as well. These features are captured in the ABRFC precipitation estimates