NOAA/CIMSS ProbSevere model display

It's a quiet start to the 3rd week of the HWT Spring Experiment. As forecasters become acquainted with the various products being evaluated, we've seen some convection fire in southeast Wyoming, but it hasn't amounted to much yet.

The NOAA/CIMSS ProbSevere model is a statistical model that fuses together satellite growth rates derived from GOES cloud products, MRMS Maximum Expected Sized of Hail (MESH), and RAP MUCAPE and effective shear (EBShear) to predict the probability that any given storm will produce severe weather. The idea is to use the 1st-order NWP environment predictors and observed satellite growth rates to give forecasters more confidence and hopefully more lead time on issuing severe weather warnings.

Figure 1 shows the display of ProbSevere in AWIPS-II. It is driven by shapefiles, which are contoured around radar-identified storms. By scrolling over the storm, you can see the ProbSevere readout. The probability of severe (SVR PROB) is first. This storm in southeast Wyoming had a 17% probability of severe. Next we see the environmental MUCAPE (949 J/kg) and EBShear (48.3 kts) computed from the RAP NWP model. Next is the MRMS MESH, equal to 0.26 inches. Lastly, the normalized vertical growth rate, characterized as "strong", and the cloud-top glaciation rate, characterized as "moderate". The strongest satellite growth rates in a storm's lifetime are used in the model. These growth rates occurred 1.25 to 1.75 hours ago. Beyond 2 or 2.5 hours, the satellite growth rates may not be that relevant to incipient storm development. This is something the forecaster should bear in mind when using ProbSevere, as well as other important environmental aspects. Recent research has shown that severe storms tend to exhibit faster satellite growth rates than non-severe storms.

Figure 1: NOAA/CIMSS ProbSevere model display, overlaid MRMS merged composite reflectivity.

-Cintineo