Jesse Risley
Staff member
It's still 72 hours out, but since it's quasi-local for me, I'll be keeping an eye on how Saturday's system progresses into Sunday as the upper-level energy gyrates out of the southern Plains into the mid-Mississippi valley. While I believe the NAM is again overdoing moisture, particularly with its northward extent, and a lot rides on how Saturday's convection plays out coupled with the evolution of ongoing convection in the warm sector coterminous with large scale forcing for ascent, if today's 12z NAM continues with its current prognostication, there is a more formidable, classic spring threat across the northern extent of the risk area into the western and central OH Valley region.
Given the potency of mid-level energy approaching the region, and the possibility of a more compact surface cyclone with better directional shear, if more formidable instability can materialize in the synoptically favorable axis south and east of the main surface low, a more substantial risk for discrete supercells could conditionally materialize. Of note is that the 12z/11 NAM run is still somewhat of an outlier here, as the ECMWF is slightly more progressive with a less nebulous SVR threat across the northern extent of the warm sector. The GFS is the most progressive and least optimistic, and continues that trend with the 18z run, showing a more diffuse surface pressure amalgamation and a fairly scantily clad warm sector in the aforesaid region. All models seem to agree with surface frontal forcing interacting with a more unstable airmass across the Gulf-Atlantic Coastal Plain and southern Piedmont region, with shear vectors more parallel to the front, generally producing a more substantial threat from linear convection there. While the NAM is advertising better LIs, favorable directional shear, and more magnanimous surface instability south of I-64 and east of I-57, across large swaths of the western OH River valley, caveats include more anemic, less latitudinous mid-level lapse rates and some rather notable VBV profiles on the wider 6 km picture, despite favorable 0-1 km shear vectors.
Nevertheless, something to keep an eye on as the system evolves over the next 72 hours.
Given the potency of mid-level energy approaching the region, and the possibility of a more compact surface cyclone with better directional shear, if more formidable instability can materialize in the synoptically favorable axis south and east of the main surface low, a more substantial risk for discrete supercells could conditionally materialize. Of note is that the 12z/11 NAM run is still somewhat of an outlier here, as the ECMWF is slightly more progressive with a less nebulous SVR threat across the northern extent of the warm sector. The GFS is the most progressive and least optimistic, and continues that trend with the 18z run, showing a more diffuse surface pressure amalgamation and a fairly scantily clad warm sector in the aforesaid region. All models seem to agree with surface frontal forcing interacting with a more unstable airmass across the Gulf-Atlantic Coastal Plain and southern Piedmont region, with shear vectors more parallel to the front, generally producing a more substantial threat from linear convection there. While the NAM is advertising better LIs, favorable directional shear, and more magnanimous surface instability south of I-64 and east of I-57, across large swaths of the western OH River valley, caveats include more anemic, less latitudinous mid-level lapse rates and some rather notable VBV profiles on the wider 6 km picture, despite favorable 0-1 km shear vectors.
Nevertheless, something to keep an eye on as the system evolves over the next 72 hours.
