UNR - SVR issued off of ProbSevere. Not a great idea!!

2125Z: Strong/Severe storms continue to move from SE WY into the UNR CWA as expected so took after quickly glancing at GLM/ProbSevere after a blog post, decided to issue a SVR based on ProbSevere & MESH values. WHen I first noticed the storm it was nearing the CYS/UNR CWA boundary & had a ProbHail of 77%, ProbWind of 53%, & MESH of 1.68". Loopping through the last 10 minutes of data I noticed an increasing trend for all values so issuing a quick warning for golf-ball sized hail based on MESH & ProbHail values seemed like a no-brainier to me. Furthermore GLM total energy showed relatively high values compared to other storms in the area so far this afternoon.

Unfortunately... after spending time on a blog post I committed the cardinal sin of warning operations & lost my situational awareness before issuing the warning. The storm began to weaken almost immediately after I issued my warning ProbHail values quickly dropping to less than 10% & GLM lightning data showing a clear decreasing trend as well. SPC mesoanalysis clearly showed these storms moving into a poor environment in NE WY with less than 500 J/kg MLCAPE, less than 30 kts effective bulk shear, & less steep lapse rates as well. I looked at the all-sky CAPE post warning as well but it was not useful in depicting the CAPE gradient from south-north in eastern WY.

Obviously it goes without saying but situational awareness & a proper analysis of the near-storm environment is essential in a warning environment. ProbSevere cannot be used by itself in a vacuum for warning decision making but rather as part of a package with other storm interrogation techniques.

ProbSevere/GLM 4 panel animation:

2030Z all-sky CAPE:

Peter Sunday