Pre-frontal Virginia convection

A few storms have fired ahead of the squall line in northern Virginia. While most storms have had very low probabilities of severe (via the ProbSevere model), one storm had a 37% probability (figure 1), owing to 0.87" of MESH, 1220 J/kg of MUCAPE, and 27 kts of effective shear. The IR and visible GOES-East imagery showed that there was a very thick cloud mass over the mid-Atlantic, damping the satellite growth rates. However, 8 minutes after the ProbSevere exceeded 30%, the NWS issued a severe thunderstorm warning (figure 2). Fourteen minutes later, a wind report was recorded in northern Virginia. This demonstrates that ProbSevere was able to identify the "storm to watch" in this region, and the probability of severe could have been aided by earlier temporal information from the satellite growth rates, if they had been observable.

Figure 1: ProbSevere highlights a storm with 37% probability in Virginia, in midst of storms with 1-10% probabilities of severe. This storm later produced a severe wind report, while the lower probability storms have had no reports.

Figure 2: NWS warning (issued at 3:50pm). 

-Cintineo