Earth Network Incorporated Total Lightning Use During the Severe Weather Event of 30/31 January 2013

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 summary below provides a recent example of the utility of the total lightning data with lower intensity convection.

se.bref.1301310041

Figure 1 – Regional reflectivity imagery from 0028 UTC on 31 January 2013

An area of showers with embedded thunderstorms moved across the Southeast on 30 January and then moved offshore during the early morning hours of 31 January. The convection was associated with an intense mid-level trough that produced a strong line of pre-frontal convection. The environment across central North Carolina was characterized as a high- shear low-instability environment with MLCAPE values of 100-250 J/KG and bulk shear values of 60-80 KT. The resultant low-topped QLCS swept east across the area during the evening and the early overnight hours with very little lightning.

NWP guidance had a good handle on the evolution of the event and the threat of severe weather was well anticipated. The very strong winds throughout the depth of the lower troposphere were responsible for several reports of down trees and power outages ahead of the main line of convection. Forecasters were concerned about whether the shallow convection would be robust enough to produce additional wind damage as it moved across the western Piedmont. Initially, there were limited reports of severe weather as the line of convection moved across the Foothills of North Carolina and approached the WFO Raleigh CWA.

ENI.NLDN.comparison

Figure 2 – Four panel plots of one hour lightning data across western NC with ENI CG data in upper left, NLDN CG data in upper right, ENI IC data in lower left, and ENI CG and IC data in lower right.

The amount of lightning associated with the convection was very limited. As a segment of the line approached the western Piedmont, the Earth Networks Incorporated (ENI) Lightning Network identified six lightning flashes across Alexander and Iredell Counties in western North Carolina including both cloud-to-ground (CG) and in-cloud (IC) lightning. At the same time, the one hour lightning product in AWIPS, provided from the NLDN network which only provides CG data (upper right in figure 2), indicated just two CG lightning flashes. Both networks identified the CG lightning in a similar location across the western border of Iredell County (top row in figure 2). But the ENI network which captures total lightning, which includes both CG (upper left in figure 2) and IC lightning (lower left in figure 2) was able to capture four IC lightning flashes which were not included in the NLDN product viewed in AWIPS.

This new lightning activity, and especially the addition of the four in-cloud lightning flashes, suggested to forecasters that the convection was likely growing taller, more intense, and potentially more likely to produce damaging winds gusts. In addition, the location of the line of convection and its orientation relative to the radar beam angle from multiple RDAs made the interpretation of radar velocity information difficult and limited in utility. The noticeable jump of lightning activity, especially the increased counts provided by the in-cloud lightning information via the ENI, was a contributor to a successful warning decision.

rah.2013.svr.001

Figure 3 – Severe thunderstorms Warning PolygFigure 4 – SPC storm reports for the 24 hour period ending 12 UTC on 31 January 2013on with reflectivity imagery from 0115 UTC on 31 January 2013 and convective wind damage reports.

A Severe Thunderstorm Warning (see figure 3 to the right) was issued for Forsyth and Davidson Counties based in part by the ENI total lightning data. While a similar warning decision may have been made without the ENI data, the ENI data provided the forecasters with a location that required additional inspection and interrogation. Given there was a long line of convection this was important. In addition, and perhaps most important, the ENI data provided forecasters with additional confidence that this particular portion of the line was likely more intense and was strengthening.

There were multiple reports of wind damage associated with the line as it moved across Forsyth and Davidson Counties as noted in the selected storm reports below and the circled area in the SPC severe weather reports map in figure 4.

0820 PM     TSTM WND DMG     1 NNW DONNAHA           36.25N  80.44W
01/30/2013                   FORSYTH            NC   911 CALL CENTER

TREE DOWN AT 6910 FISHER ROAD. TIME ESTIMATED BY RADAR.

0845 PM     TSTM WND DMG     1 NNE KERNERSVILLE      36.13N  80.07W
01/30/2013                   FORSYTH            NC   911 CALL CENTER

TREE DOWN ON PORTER LANE.

0900 PM     TSTM WND DMG     2 N LEXINGTON           35.84N  80.25W
01/30/2013                   DAVIDSON           NC   BROADCAST MEDIA

TREES BLOWN DOWN NEAR VIRGINIA DRIVE.

spc.reports.map

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