March 15, 2025 Long-Track Tornado Event // Southern MS and Adjacent LA

 A long-lived long-track tornado moved northeast across southeast MS during the early afternoon of March 15, 2025. The EF4 tornado had a pathlength of 109 km and lifespan of 82 minutes. An 18 UTC HRRR proximity sounding was captured for Hattiesburg, MS, which was located a few 10's of km east of the tornado track. That sounding profile was used to test a tornado pathlength and duration algorithm, and the predicted values were an 85 km pathlength and 74 minute duration, which was in error of 24 km and 8 minutes, respectively.

 The large-scale environment was fairly typical of a tornado-producing synoptic-scale storm system. Mid and upper flow was enhanced around a trough moving across the middle United States. Embedded speed maxima were present at 250 mb, with one impulse rotating out of the trough and across the region of tornado production. In the low-levels, southeast flow ushered low 70s dewpoints into southern MS by midday. Midlevel lapse rates were also fairly steep above the moist boundary layer, around 7 C/km, and this aided in MLCAPE values near 2000 J/kg. Tornado longevity was likely enhanced by 20 m/s of bulk-wind difference from the surface to around 1 km AGL. And convective mode was initially favorable for tornadic supercells, though trended toward QLCS later in the day.

All in all, a fairly standard long-lived long-track tornado environment. Nothing stood out in particular. The environment supported the observed tornado attributes and the environment produced as expected.

Thanks to Kathy Kanak for sharing ideas and providing much of the data used in this post.

18 UTC HRRR proximity sounding located several ten's of km east of a long-track tornado.

Damage survey tornado track for the long-lived long-pathlength event in southern MS.

MRMS rotational tracks.

Tornado pathlength and duration prediction algorithms for the long-track event in southern MS.

Subjective surface analysis valid 18 UTC for the long-track tornado event in southern MS.

250 mb objective analysis valid 00 UTC 16 March 2025.