12/28 FCST: LA/MS/AL

[Dave Ewoldt]

24/00z gfs/nam are in good agreement at 84 hours with a strong upper sys movg quickly ewd through the southwest u.s. By the 28th... the gfs has a strong vort center in louisiana with 50 kts of h5 wind spreading across ms/al. A 1002 mb sfc low is forecast to be in northwest mississippi with a narrow - but suffly unstbl zone of warm sector air spreading to the TN border that would support severe convection. Prob not a huge event....but if it verifies, I would think that we have a chance to add to the 2005 U.S. tornado count.

 

[Brett Adair]

27/00z GFS/NAM seem to be a bit moisture starved in the PBL. Our CAPE numbers do get up there AOA 1000J/kg due to the extreme cold air aloft, but the raw numbers only indicate us getting to near 62 degrees. I question that somewhat with a 998mb SFC low setting up shop in SE MO. However, when the main action fires the best shear/LLJ axis has shifted N and Eward. Looks like any sustained mesocyclone formation will be down near the coast of SE AL/SWRN GA, FL PHDL where the deepest boundary layer moisture will be present. Hailers will be common given -20 H5 temps in WRN AL. 0-1km SRH and 0-3 km deep layer shear could support a limited tornado threat, but with very dry mid levels mixing into a marginally moist environment the LCL's are going to be kicked up a few hundred feet. Maybe even a Kft or so....it is something that needs to be monitored since the latest GFS shows a bit more moisture and quite an upper level system pounding in.