[5] While March 29 translated to a level 2/Slight risk of severe weather stretching from Iowa southward to Texas,[6] a broader and more significant threat area began to materialize across the Southeast valid for the following day.

In this region, forecasters noted the potential for an extensive squall line capable of producing hurricane-force damaging winds and numerous tornadoes, some of which could be significant/EF2 or greater.

A potent and negatively-tilted shortwave was expected to round the base of this larger trough, providing substantial upper-level divergence for thunderstorm development across a broad region.

At the surface, a quickly deepening area of low pressure was forecast to move across Missouri and Illinois, providing significant advection of moist air into its open warm sector.

Into the afternoon hours, with continued moisture advection and surface heating contributing to additional instability, a well-organized squall line began to intensify as it moved across Arkansas, Louisiana, Mississippi, and eventually into Alabama.

[12][13] Across central and coastal sections of these states, environmental conditions became more conducive for the squall line to devolve into a series of semi-discrete supercell thunderstorms, with a heightened risk of tornadoes.

[135][136][137][138] Intense winds relating to the system on March 31 forced flight cancellations out of major airports in Washington DC, Baltimore, New York City and Boston,[139] as well as lead to a 3-car pileup in Iota, Louisiana.