A QUICK GLANCE AT COMPOSITE REFLECTIVITIES MAY BE MISLEADING

摘要

Only through the high resolution of the WSR-88D which offers 16 dB2 levels (the WSR-57 would have shown just one VIP level of return) could the location of the snow be pinpointed. Using a cross-section, the potentially confusing slant of the snow as it fell was understood, and precipitation was not forecast to fall under the highest reflectivities. Care should be taken when using volume products to assess precipitation actually striking the surface. When composing products such as Terminal Forecasts and Short Term Forecasts using WSR-88D products, the forecaster should consult both Composite Reflectivity and individual Reflectivity slices such as the 0.5 degree product. The four panel presentation (Figure 6) contains a 16 level Composite Reflectivity (upper left), a 16 level 0.5 degree Reflectivity (upper right), an 8 level 0.5 degree Reflectivity (lower left), and an Echo Top product (lower right). While the Composite reflectivity indicates returns in excess of 24 dBZ across southwest Hodgeman county and northeast Ford county, the 0.5 degree slices showed spotty returns of less than 5 dBZ. Echo tops of 15,000 to 18,000 feet were indicated over northeast Finney County, coinciding with the highest reflectivities. However, tops of less than 5,000 feet were located along highway 50 from Garden City to Dodge City, where the snow was actually reaching the ground.