Dan Robinson
EF5
The first viable tornado chase opportunity looks to be on our doorstep, a typical Midwest winter event where a significant wave manages to bring moisture northward under one of the cool season's many potent shortwaves. Dewpoints reaching 55-60F will wrap into a surface low with the classic arc of supercells blooming to the southeast of the low. Models have been slowly improving the thermodynamics of this setup, leading to sufficient low-level instability to support a respectable tornado threat on par with many similar events we've seen in this region between December-February in the past.
CAMs have been rather messy with this event, depicting multiple waves of storms beginning in the late morning near St. Louis and tracking generally northeast along the I-70 corridor into Indiana. While the I-70 depictions would make for a convenient chase, what typically happens with these is the more classic arc of supercells setting up from Peoria through Mount Vernon, with the northern cells in the arc more favored for tornadoes (closer to the surface low vorticity and better low-level turning). However, the core of the jet has been shown farther south, and storm motions should be more easterly in these regions. CAM UH tracks are also not as useful in these setups, as I expect that any discrete storm will have a healthy low-level meso (not just the I-70 storm that the HRRR wants to highlight).
I'm not sure I buy the viability of the early storms, as they could be more elevated/across the boundary. I'd be leaning more toward the later-firing cells to the west as the better plays. We'll also need to watch the look of the dry slot at the morning's first satellite image - a good one will of course portend a better result. My feeling right now is to stage between Vandalia and Effingham to hedge for the morning activity, then leave those and get into position slightly SW of there for the main round later.
CAMs have been rather messy with this event, depicting multiple waves of storms beginning in the late morning near St. Louis and tracking generally northeast along the I-70 corridor into Indiana. While the I-70 depictions would make for a convenient chase, what typically happens with these is the more classic arc of supercells setting up from Peoria through Mount Vernon, with the northern cells in the arc more favored for tornadoes (closer to the surface low vorticity and better low-level turning). However, the core of the jet has been shown farther south, and storm motions should be more easterly in these regions. CAM UH tracks are also not as useful in these setups, as I expect that any discrete storm will have a healthy low-level meso (not just the I-70 storm that the HRRR wants to highlight).
I'm not sure I buy the viability of the early storms, as they could be more elevated/across the boundary. I'd be leaning more toward the later-firing cells to the west as the better plays. We'll also need to watch the look of the dry slot at the morning's first satellite image - a good one will of course portend a better result. My feeling right now is to stage between Vandalia and Effingham to hedge for the morning activity, then leave those and get into position slightly SW of there for the main round later.
