Construction of hail swaths using NIDS data

In the early 1990s, the nation's first WSR-88D began operations in central Oklahoma. Most users of the WSR-88D information access a subset of NEXRAD products made available through the NEXRAD Information Dissemination Service (NIDS). To demonstrate the beneficial use of NIDS data to the insurance industry, illustrative but real swaths of severe-sized hail were produced using NIDS data; namely, the Vertically Integrated Liquid (VIL) product and output from the Hail Detection Algorithm (HDA) generated by the WSR-88D at Oklahoma City.

Three examples of hail swaths were constructed using the following criteria: a Probability of Severe-sized Hail (POSH) > 50% and a variable monthly threshold that also had to be exceeded. The VIL product is comprised of 116 x 116 grid boxes with a spatial resolution of 4 km x 4 km for each grid box. If the latitude/longitude location of a POSH > 50% occurred within a 4 km x 4 km grid box in which a VIL value exceeded the threshold for a volume scan, then one occurrence of severe-sized hail would be counted for that particular grid box. Computation of the approximate length, width, and areal size of the swath can then be achieved.

Based on these results, it appears the NIDS data, when properly applied, can alert the insurance industry to the precise geographic location where damaging hail may have occurred by detailing the areal coverage of a hail swath. Even though the proposed swath technique has not been perfected yet, this first-of-its kind scheme in detailing hail swaths should provide evidence that NIDS data is a valuable tool that awaits use by the insurance industry.