Latest SPC outlooks. Outlook for Thursday has been expanded northward significantly due to confidence in a deep rich airmass supportive of severe storms being present. We have a very potent long wave trough ejecting into a very rich warm sector. As others have noted when folks start this low rumbling this far out they know something is up. I expect a steady uptick in messaging in the days to come.
"The focus for severe is overwhelmingly concentrated on Wednesday
through Thursday across parts of the southern Great Plains eastward
into the MS/OH/TN Valleys. Model guidance continues to show a very
powerful upper-level system ejecting into the southern Great Plains
on Tuesday from the Desert Southwest. Additional modification of
the airmass across the northwest Gulf Coast will aid in
severe-thunderstorm potential. Surface dewpoints will probably
reach the lower-mid 60s in the Arklatex on Wednesday into Wednesday
night. Model variability and greater confidence and a farther-west
edge of low-level moisture/surface low placement in the southern
Great Plains necessitated a shift of the severe probabilities west
on Wednesday (day 5). Once model spread is reduced, a 30-percent
severe area will likely be introduced. A continuation of
thunderstorm activity will likely occur into Thursday as the warm
sector potentially develops as far north as the OH Valley. Have
expanded the severe risk as there is now greater confidence in the
forecast surface-low track on Thursday being across parts of the
Midwest. Model spread increases by late in the extended period
before severe potential likely becomes very low next weekend."