Day 4: Nashville CWA, May 12

Things are developing quickly early this afternoon over the Nashville, TN CWA. A sharp cold front is racing toward the region and will trigger some linear convection over the next couple of hours. Here is the WPC frontal analysis from 18Z.

Out ahead of the front, we have a decently unstable air mass. The 12Z KOHX Nashville sounding showed about 1200 J/kg of Most Unstable CAPE.

The GOES LAP data from 15Z confirmed this pretty well. The LAP was mostly populated with the GFS over our forecast area, but there was an area of cloudy retrieval that indicated 1000-1500 J/kg of CAPE. The GFS values were again much lower.

LAP derived layer precipitable water values of 1.5-1.6 inches moving into the region with the cold front. Given that instability is relatively modest and the shear profile is not all that impressive, we are thinking that the main convective threats today will be heavy rain and straight line winds with the cold front.
- JP