Tornadoes in northern Louisiana

With a QLCS moving through yesterday, many local storm reports (LSRs) were delayed. The time series below show how ProbTor (Figure 1) and the other ProbSevere products (Figure 2) performed with respect to official NWS warnings and reports. Several forecasters at HWT this week have noted that they look for jumps in ProbSevere and ProbTor to help identify threats and provide confidence in their warnings. For the storm segment below, there was a jump in ProbWind about 8 minutes before the first tornado report ("widespread damage" reported) and a jump in ProbTor 4 minutes prior to the tornado. Increases in lightning activity and 0-2km AzShear helped jump the probabilities.

Figure 1: ProbTor time series for a tornadic storm. The jump in ProbTor was due to a sharp increase in 0-2km AzShear and and increase in ENI lightning density.

Figure 2: ProbSevere products time series compared to NWS warnings and LSRs.