5. Complex Terrain/Radar Scanning Issues

The range of the storm from the radar is an important factor. If cloud base convergence is being evaluated, the correct tilt must be used. The proper tilt is a function of the cloud base height and range from the radar. For example, if the cloud base is estimaged to be 3000 m and the cell is 75 km from the radar, the 1.4° tilt should be used. Also as mentioned earlier, the important echo core is relative to the cloud base.

Obtaining in situ liquid water and ice content values is difficult at best, so estimates are obtained through the use of the WSR-88D radar. Figure 9 is an example illustrating volume sampling of a microburst storm by the Salt Lake City, UT (KMTX) WSR-88D radar when operating in Volume Coverage Pattern (VCP) 21. The proper choice of VCP and corresponding elevation slice(s) is imperative for proper sampling of reflectivity values near cloud base. Since most pulse-type storm cells have relatively short life spans (e.g., < 30 min), it is recommended that VCP 11 be used due to its higher resolution vertical (14 elevation slices) and temporal (5 min) sampling.