Along with other output, the model sent forecasters in Norman a sequence of images they could display on workstations as a moving picture of how the storm would evolve during late afternoon and early evening. Nevertheless, experienced forecasters found that even this simplified version of ARPS was useful. Forecasters gained enough confidence in the model that on May 21 they referred to it in an official National Weather Service release indicating the potential for intense thunderstorms over Oklahoma that evening. These images show snapshots from the ARPS prediction for rainfall over central Oklahoma on Mother's Day, Sunday, May 9, 1993. Each image represents a 100 x 100 kilometer square horizontal slice through the storm four kilometers above ground level, showing what the storm would look like on a radar scope, where reflectivity corresponds to how hard it's raining.
Color indicates rainfall intensity, increasing from light blue to pink.
Severe storms on Saturday, May 8, and again on Sunday resulted in several tornadoes and heavy flooding in parts of Oklahoma, and ARPS successfully forecast this threat. The rainfall images show multiple supercells forming into a line. This agreed well with what was observed. Saving Money and Lives By increasing the lead time for severe storm warnings, ARPS has the potential to reduce property damage and save lives. It should also make it possible to give more precise information about impending storms.