In the 4-panel image above from 1955z over northern Virginia the ProbSevere model was evaluated on a low-topped bowing line of storms. The developer has noted poor performance in liner convection but wanted to evaluate its utility in storms with damaging winds.

The top left pane shows 0.5 deg reflectivity from LWX radar with the ProbSevere model shapefile overlaid. The top right pane shows 0.5 deg velocity and the lower left pane is enhanced echo tops. The mouseover shows inbound velocities of around  50kts at the nose of the bowing convective line with enhanced echo tops only to 20kft (low-topped). This line of storms is likely producing some damaging winds but the low-topped nature of the convection should preclude any hail. The ProbSevere shapefile of predictors indicated only a 1% probability of a severe storm in an environment with 620 J/kg of MUCAPE and a healthy 36.2 kts of EBShear (High Shear Low CAPE). The MESH product is likely performing well since it only indicated hail to 0.08 inches. This case further supports the lack of utility of the ProbSevere model in liner convection. However, I continue to feel that its best use is for detecting storms which can produce severe hail.

Shawn Smith