Iowa Supercell

A pristine environment for supercells developed across Iowa this evening with large instability (MLCAPE >3,000 J kg-1) balanced by strong deep layer wind shear (55 kts). One large, discrete and cyclical supercell has persisted for the last several hours over southwest Iowa, and has occasionally produced large tornadoes. This is a classic example of a supercell riding along a boundary and ingesting large amounts of storm relative helicity, which helps aid in tornadogenesis. For more information about this, I highly recommend the Markowski et al. (1998) paper.

Tomorrow's severe weather environment setup looks great for a large portion of the Central and Southern Plains. The western U.S. trough swings out into the Plains tomorrow and should provide the lift necessary to generate a severe weather outbreak. It appears that storms should initially develop across Nebraska as discrete supercells, but they should congeal into a linear complex somewhat quickly given the parallel orientation of the deep layer shear vectors to the front. Further south across Kansas and Oklahoma, it appears as though the winds may be slightly more perpendicular to the front to allow for a longer period of discrete storms. Therefore, this should increase the risk for a tornado outbreak across these two states, especially given that 0-1 km SRH values are forecast to range between 150-300 m^2 s^-2. Sadly, I'll be arm chairing this event.