Psuedo-GLM Products in the Mid-Atlantic

Forecasters conducted warning operations in the Sterling, VA and State College, PA CWAs, which allowed for analysis of the pseudo-GLM products (from the DCLMA). Although the earliest convection initiated along and just west of the Appalachian Mountains (out of range of the LMA), storms soon formed within range. Isolated storms initiated and developed rapidly ahead of the main line. The pseudo-GLM products detected IC flashes ~10 min prior to the first CG flashes in two of these storms. These storms continued to intensify and eventually merged into a line, further increasing the flash rates.




As the discrete cells merged into a line, flashes remained frequent, and the pseudo-GLM products helped confirm the strength of individual cells within the line. Greater flash rates also helped identify areas of new convection as they formed along the line.



Forecasters also observed that the pseudo-GLM swaths (i.e., 60 min sum of flashes) helped to illustrate persistent cells and identify the most intense portions of the line.



The above screen captures illustrate several four panel displays used to compare individual products in AWIPS. The pseudo-GLM products often were plotted alongside the 3-D Var updraft and vorticity tracks, as well as the multi-radar multi-sensor hail swaths and reflectivity at -10 C.

Scott Rudlosky