There are a couple of observations I made as to why yesterday failed to produce.
1) lack of strong LLJ. This was apparent from modeling about 24 hours out and very noticeable yesterday. Even when the sun broke out and mixing should have occurred, winds were pretty much calm all afternoon until the outflow from the QLCS came through. On significant severe days, as soon as the sun breaks out and screaming LLJ winds start mixing down, it becomes extremely windy and gusty
2) The meso-low develop in a textbook location from pressure falls along the southern edge of the retreating wedge layer and rode that boundary to a T. This happens so frequently we need to look past other parameters in our area and always remember that these meso scale systems frequently are our main mode for severe weather. The only significant weather yesterday occurred with this feature and it was well outside the area SPC progged for severe weather.ALWAYS watch the wedge front for severe, even if CAPE and other values are not high in those areas
3) as the low crossed the mountains it got strung out. Pressure falls along the coast set up a secondary boundary that became the primary forcing region and led to the formation of a large area of convection near or over the ocean. This was very well modeled within 36 hours. Most CAMs eliminated all convection in the SPC risk area more than a day out. This was very noticeable. Whenever you get a large convective mass on the coast you can pretty much kiss severe threats goodbye. Not only was the LLJ disrupted but a large area of subsidence existed between the pressure falls along the coast and the meso low. This negated the favorable mid level parameters that argued for an outbreak
4) do not take so much stock in mid level parameters. They definitely determine a severe outbreak, but to be exploited you need storms, lol. This was a situation where the LP got strung out and reformed over the coastal boundary leaving most of NC/SC in a zone of subsidence and no forcing for storm formation. This was actually very well modeled from 24-36 hours out, plenty of time to adjust the severe outlook