Since late 2011, the NWS Raleigh (RAH) has been evaluating products from Earth Networks Incorporated (ENI), in particular data from ENI Total Lightning Detection Network (ENTLDN). ENI provided access to their data (real-time and archived) along with a web-based software tool, called Streamer-RT. RAH has evaluated numerous cases and has found the dataset useful in several forecast and warning applications. The evaluation has noted that the ENTLDN data has been especially helpful in evaluating modest convection and in particular sub-severe convection that is intensifying and growing into thunderstorms. The summary below provides an example of the utility of the ENTLDN data with the Greensboro N.C. (KGSO) Terminal Aerodrome Forecast (TAF) late on 07 July 2013.
Scattered showers and isolated thunderstorms moved across the western Piedmont of North Carolina during the evening of 07 July. The area of convection that was approaching KGSO generally weakened during the 0100-0230UTC period with the cloud-to-ground (CG) lightning as indicated by the AWIPS NLDN data indicating no CG lightning after 0230 UTC. When the overnight shift arrived at 0300 UTC, it initially appeared that a cluster of moderate rain showers were approaching KGSO with no CG strikes noted in the NLDN data in AWIPS.
Examination of the reflectivity structure of the convection approaching KGSO revealed that there was the potential for lightning as reflectivity values in excess of 40 dBZ extended above the -10 degrees C altitude (see page 2 of this reference for more information on this technique). The 00 UTC RAOB at KGSO indicated the -10 degrees C height was approximately 19,800 feet AGL and reflectivity values from KRAX from the 0313 volume scan at 2.4 degrees or 23,672 feet AGL were > 40 dBZ. Based on the radar data and despite the lack of CG lightning indicated from the AWIPS NLDN, the decision was made to add a thunderstorm to the TAF for KGSO.
Prior to the transmission of the TAF, total lightning data from ENTLDN was consulted. The total lightning data which includes both CG and in-cloud (IC) lightning (shown below on the right) showed around 15 total lightning flashed during the one hour period from 0215-0315 UTC. During the same period, there were no CG flashes (shown below on the left) indicating that all of the lightning during this period was IC. Thus, the NLDN would never have picked up on the lightning; the ENTLDN was the only way to confirm the lightning. This demonstrates that the addition of total lightning data provides significant and critical information beyond what the NLDNCG data provides.
Experience has shown that many times lightning first appears in thunderstorms as in-cloud lightning before CG lightning occurs. This was true during this event as the first CG lightning was observed at 0328 UTC, about 8 minutes after the TAF was updated and about 15 minutes after the 40 dBZ echoes exceeded the -10 degrees C level. The CG lightning would certainly not have been a surprise with the use of the total lightning data.