All eyes are watching this severe weather risk today, Wednesday April 5, 2017 afternoon and evening across the Kentucky, Indiana and Ohio. All potential hazardous weather is possible at this time including wind, rain, hail and even a possability for long-duration EF2-EF5 long-duartion tornadoes, especially outside of our region in Mississippi and Alabama.
As this low pressure system moves into the Ohio Valley, a warm front lifts through in the morning hours today. Storms should develop in the warm air by afternoon ahead of the cold front which is expected to bring a dusting of snow to us this weekend! The farthest points south we will likely get today will only provide a medium risk for severe weather but this could chage as the day progresses. Most model data gives us ample instability and wind energy to support severe weather. This skew-T chart from the NAM model shows the turning wind directions in the lowest 2 kilometers of the atmosphere, dew points near 60 degrees and CAPE (instability) values over 1000 J/kg.
One caveat to this entire severe weather setup. If our dew points "mix down" into the 50s because of the expected sun and breeze ahead of the storms today, the severe weather risk will not be as high as initially expected this morning. This has happened on multiple occasions in the past, particularly when our surface wind direction is southeasterly. While it would not squelch the threat completely, the hazards of concern would lessen the liklihood of tornadoes but leave the potential for wind and large hail. Stay connected with your NOAA Weather Radio today as well as mainstram news outlets and radio as we should all be prepared for severe thunderstorms today not ruling out the possability for a tornado watch/warning situation!
An outbreak of severe thunderstorms with a few strong tornadoes, very large hail, and damaging winds is expected today into tonight from Alabama and Georgia into South Carolina, as well as northward into middle and eastern Tennessee and central Kentucky. For our immediate area, the Storm Prediction Center states an increase in low-level moisture will occur today from TN northward to the lower OH Valley, in advance of the surface cyclone/cold front and west of the ongoing convection across AL/GA. Some surface heating will occur ahead of the front per morning satellite imagery, which combined with the moistening, will result in a corridor of moderate buoyancy extending northward from northern AL across middle TN into central KY, and perhaps southern IN. Convective initiation is expected along or just ahead of the front by mid afternoon, with sufficient cross-boundary flow/shear for discrete storms to move off the boundary. Deep-layer vertical shear and buoyancy will favor supercells capable of producing large hail and damaging winds, while a branch of the low-level jet across TN/KY will provide sufficient low-level shear for isolated strong tornadoes from about 7pm-9pm EDT.