In 2001, WDT began archiving NEXRAD data along with information from the Hail Detection Algorithm (HDA) for commercial applications. These data and technologies in combination allow for the determination of hail swaths of 0.75" up to 2" (large hail) and 2" and greater (very large hail).
Studies have shown that the HDA is skillful in determining whether a given storm will produce hail. One study performed in Colorado showed the HDA correctly determined which storm was producing hail 92% of the time with an extremely low false alarm rate of 4%; (Witt et. al. 1998). Also, based upon a geographically diverse radar dataset, the HDA has demonstrated very accurate detections of severe hail including the probability of detecting hail greater than 1 inch (87% of the time) and 2 inches (96% of the time). The accuracy of these results is based on hail detection using a single radar. WDT's proprietary algorithm utilizes overlapping data from multiple NEXRADs that cover the area of interest.
This allows iMapWeather Forensics to achieve probability of detection of hail nearing 100% over the lifetime of hail generating storms. Of course, performance is a function of atmospheric conditions, proper operation and calibration of the radar and quality reports of hail.
