A handful of severe thunderstorm warnings were issued for the Pittsburgh CWA by our team today given upticks in the satellite signatures. A pea-sized hail report came in at 1951z and this allowed us to calibrate the satellite signatures to the intensity of the storms. Thus, given the uptick in both Gremlin and Octane, we were able to realize that it would take a bit stronger of a signal to warrant large hail and potential a downstream warning.

Figure 1: Gremlin East CONUS reveals a rapid uptick in dBZ just before the pea size hail report at 1951z.

Figure 2: OCTANE already revealed CTD present in the part of the line that produced the hail report. Additionally, the cloud tops seemed to cool more just before the hail report.

– Aurora Borealis

In addition to my colleagues above, while in warning Ops today, it was noted as a group that after some initial calibration of what was going on weatherwise and looking at the Octane Products, the Octane products look to have at least done a slightly better job at noting which convection was just weak enough to not produce hail or wind reports while radar data might have struggled slightly more with pointing out wind and hail threats overall and what storms were the strongest.

Figure 3: Cells on the southern end of the map in the (orange circle) had more significant cloud top cooling but was much shorter lived and cloud top divergence was also slightly weaker. These storms failed to produce more than pea sized hail and no wind reports. While storms noted further north (pink circle)  while they had slightly weaker cloud top cooling with a more sustained cloud top divergence was responsible for some wind reports and potentially a tornado.

Meanwhile focusing on one of the radar related four panel products I tend to use in warning ops when differentiating between what storms to look at, the farther south storms, tended to have higher Vertically integrated Ice, higher MESH values, and overall looked slightly more structured than storms at the far northwestern periphery of the area. However, the further north storms are the ones that ended up producing winds reports which correlated with the better divergence aloft signal found in figure 1.

Figure 4: (Panel Contents from Upper left to Lower left: Upper left panel is RALA, upper right panel is MESH, lower right panel is 30 min rotation tracks, and lower left panel is Vertically Integrated Ice.

So overall it appears at least in this instance, the trends in upper level divergence as well as cloud top cooling may have been a slightly better indicator for potential severe thresholds of storm activity across the PBZ CWA.

-Sting Jet