The GREMLIN radar product is shown above in the top left while MRMS composite reflectivity is on the top right. The two storms in question have severe warnings on them in this loop. The thunderstorm in the southwest is more isolated from other convective cloud debris, while also displaying a more intense thermal couplet and cloud top divergence signal than the thunderstorm to the northeast. It seems likely that this is the reason why the northeast storm has a lower ceiling for GREMLIN reflectivity than the southwest storm, even though the MRMS composite includes a 60 dBZ core in the northeast storm.

-Joaq