Summary
Thhis report investigates the observability of low-level wind shear events using Doppler weather radar through a comparison of radar and surface wind sensor data. The data was collected during 1986 in the Huntsville, AL area as part of the FAA Terminal Doppler Weather Radar (TDWR) development program. Radar data were collected by both an S-band radar (FL-2) and C-band radar (UND). Surface data were collected by a network of 77 weather sensors covering an area of enarly 1000 square km centered approximately 15 km to the northwest of the FL-2 radar site. The UND site was located at the approximate center of the surface sensor network. A list of 131 microbursts which impacted the surface sensor network is presented. Particular emphasis is on the 107 events for which both radar data and surface data where available. Of these events, 14 were not observed by the surface network, while two events were not identified as microbursts by radar. Possible explanations of these missed microburst identifications are presented. The first case was an instance of the radar viewing a weak, asymmetric event from an unfavorable viewing angle. The second case describes an extremely shallow microburst outflow occurring at a heigh too low to be observed by the lowest elevation scan of the radar. In each of these cases, the featured microburst was very weak and, although a microburst-strength differential velocity was not observable by radar, in both instances the divergent wind pattern associated with the event was clearly evident in the radar velocity data field. All microbursts which exhibited a differential velocoity of in excess of 13 m/s were identified by radar. No microbursts went unobserved as the result of insufficient signal return.