November 5, 2018
A low cape-high shear setup arose on this date. A negatively-tilted shortwave moved through the south central US during the day and into the Mississippi Valley by the late night. The surface low was in Texas at 00z with a warm front along the Arkansas-Louisiana border and on through central Mississippi.
The SPC outlook covered the Tennessee and lower Mississippi Valleys with a slight risk, and an enhanced area was outlined for central and southwestern Tennessee, northern and central Mississippi and southeastern Arkansas. This included Memphis and gained everyone’s attention.
Forecast soundings for this area showed a really, really low cape and very, very high shear combination. If you could get an updraft to sustain itself it would likely go crazy. Early afternoon cells in central Arkansas showed mid-level rotation, so at least that was favorable. My forecast for MEM was for severe thunderstorms in the area late in the day and early evening, with several false alarms for tor warning due to the ridiculous helicity.
The 850jet was aligned from northern Louisiana northeastward to central Tennessee. The mesoanalysis page focused composite parameters bullseyes in northern Louisiana and this verified with a large tornado around the Natchitoches area. There were some wind damage reports over northern Mississippi but nothing for this immediate area. The meso page showed the best cape was way down south and this is reflected in the VORTEX-SE soundings.
Storm movements reached 50mph, the sun set at 5pm, and I was glad I let this one go
