GLM first identified developing storm in WI

1923Z: Weak storms continue to develop across MN & WI in the absence of any major forcing feature & marginal instability. While we're acting as WFO DLH I noticed an area of increasing GLM fields in central WI shortly before 1900Z where otherwise no other convection was ongoing. While there is an 8 minute gap in the 1-minute satellite data from 1858-1906Z the IR values really didn't begin to pique my interest until 1910-1915Z. Also, a noticeable increasing lightning trend with ENTLN data wasn't really noticed until 1905-1910Z as well so GLM was able to capture the initial electrification of this storm with few minutes extra lead time. On a day like today when monitoring areas of cumulus for the first convective echoes to develop, GLM (especially GLM total energy) was especially useful.

Peter Sunday

UNR - GLM/ENTLN lighnting data on a severe storm in SD

ProbSevere indicated a severe thunderstorm that explosively developed along the SD/NE border. This storm initiated in a favorable environment & I anticipated it to further develop, so the rapidly increasing values in the ProbSevere values along with an increase in CG activity from the ENTLN were plenty for me to feel confident in issuing a warning for 2" hail.20 minutes after my warning, ProbHail had increased to 99% with a MESH value of 2.25".

For comparison, I looked at the GLM data along with observed lightning data from the ENTLN. The ENTLN showed an obvious increase in CG activity beginning around ~0015Z from the ENTLN data. However, there never was an obvious increase in GLM flash extent density or total energy.

GLM/ENTLN loop:

Peter Sunday

UNR - Comparison of GLM & ENTLN lightning data

2015Z: I noticed rather low values of GLM flash extent density & total energy with a severe warned storm near Wheatland in eastern WY so out of curiosity I decided to plot observed CG & cloud flashes from the ENTLN. Despite low values of Flash extent density & total energy the earth based network observed a rather active storm with numerous CG flashes & even more cloud flashes. The total energy product seemed to perform better than flash extent density in conveying the lightning activity in the storm & potential strength of the storm, but if I was only using GLM in a vacuum I likely would have greatly underestimated the potential of this storm. It is becoming more evident to me that the GLM output can differ drastically for "severe" storms depending on the environment, geographic region, & even from storm to storm during the same event.

GLM/ENTLN 4 panel loop:

Peter Sunday

GLM offset with ltg jump

GLM overlaid with ENTLN data showing GLM offset to the northwest of the storm.  Ltg jump occurred over the few previous frames as storm seemed to cycle again, with dBZ nearing 75