New outlook from the SPC overnight raised probabilities to 30% in the Day 4 outlook on Wednesday across most of Mississippi and Alabama. Their confidence is quite high at this range regarding the potential for a major severe weather event:
“
On Wednesday, convection will likely be ongoing across the eastern
Texas/Arkansas/Louisiana areas, with some severe risk possible
during the morning hours. By afternoon, an increase in coverage and
intensity is expected as closed upper system shifts out of the
Plains toward the Mississippi Valley. With a rather
large/destabilizing warm sector and ample shear across a broad
region, a rather large 15% area will be maintained, representative
of an all-hazards severe risk. Corridors of greater risk --
including possibly more concentrated tornado potential -- may evolve
during the afternoon, possibly near the northward-moving warm front.
While the ECMWF is farther south with this west-to-east front
(central MS/AL) during the afternoon than the GFS (southern TN),
will nonetheless introduce a 30% risk area -- encompassing a range
of possible warm-frontal locations -- given likelihood for
widespread severe weather that warrants greater probability at this
time. ”