Convection firing in the Ohio River valley

A supercell formed early on in Indiana on May 21, 2014. This storm had strong satellite growth rates (derived from GOES cloud products) by 16:37 UTC and a probability of severe of 38% (MESH was only 0.3 in.) As the MESH increased, ProbSevere values increased into the 70-80% range. With some weakening of the storm, the probability of severe decreased to 45%, but then increased again to 70-90% when it was warned on by the NWS at 17:32 UTC. From when ProbSevere first crossed 60%, there was 48 minutes of lead time. This storm would later produce 1.75" hail. It should be noted that forecasters shouldn't necessarily issue a warning when ProbSevere crosses some probability threshold, but rather monitor the ProbSevere and radar trends, using the satellite growth rate information to hopefully increase confidence and lead time to severe hazards (since stronger satellite growth rates tend to be exhibited by more severe storms).

-Cintineo/Sieglaff