Contrary to other potential severe high-shear, low-CAPE (HSLC) setups so far this autumn and winter, tomorrow’s setup appears to have the majority of pieces in place. The main story may be the high-CAPE setup during the afternoon and early evening across the Mississippi and Tennessee Valleys, areas encompassed by the Storm Prediction Center’s Day 2 enhanced risk. However, many signs point to a continued threat overnight extending into the Ohio Valley. While this will again occur west of several of our collaborating WFOs, it will likely be an event worth studying.
Figure 1, valid at 0000 UTC December 24th, shows a strong, negatively tilted trough across the Midwest with an attendant 850 hPa closed low and intense low-level jet. A baroclinic zone is evident in the 2-m theta-E field across the Midwest and Ozarks, with a warm sector extending into Great Lakes region. The EHI shows a “reservoir” of favorable values extending from the Ohio River southward into the Deep South. Additionally, SREF mean SHERBS3 (Fig. 2, left) and SHERBE (Fig. 2, right) values remain enhanced across the Tennessee and Ohio Valleys from 00z through 06z, suggesting a continued threat of severe weather during the overnight hours.
Finally, despite fairly modest lapse rates overnight in the Ohio Valley (Fig. 3) compared to those farther south (Fig. 4), hodographs appear favorable for the development of embedded rotation within an evolving QLCS in both locations.
Though this may not get a lot of comments due to the holidays around the corner, I wanted to post a brief overview due to the heightened threat. This should be quite an event to watch!