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The radar time-height cross-section in the previous slide took research meteorologists several days to produce. How can the operational meteorologist assess the potential for CG lightning in real-time? The instructors encourage forecasters to use the AWIPS four-panel radar plot and a proximity sounding.

Frames 1-4: Radar data from the WSR-88D in Denver and temperatures derived from the Denver sounding shown earlier. Five-minute CG lightning data is also plotted. These four frames correspond to the four periods of heavy precipitation discussed with the previous slide. The radar/temperature data highlight the shallow nature of the first two periods of heavy precipitation and the greater depth of the second two periods of heavy precipitation. As in the previous slide, the 45 dBZ at –10°C threshold distinguishes those storms that produce CG lightning and those that do not. However, Frame 4 shows that this threshold does not work at all times. For this reason, we consider the radar threshold a necessary but not sufficient condition for CG lightning.

Frame 5: This four-panel plot shows storms southeast of Denver. Three of the storms meet the 45 dBZ at –10°C threshold, yet not all produce CG lightning. Again, this reflectivity threshold is a necessary but not sufficient condition for CG lightning.