SPC Mesoscale Discussion: Severe Potential… Tornado Watch Likely

SUMMARY…Storms will move into the discussion area late this afternoon and early evening. Observational and numerical model trends both suggest and increase in the potential for damaging winds and tornadoes. A tornado watch will likely be issued by 4 PM CDT.

DISCUSSION…Afternoon boundary-layer mixing has reduced dewpoints across the discussion area by 1-3 F. Still, modifying the 18Z BMX sounding with surface observations across the region suggests that capping is eroding across southern Alabama and vicinity with destabilization perhaps a few more hours away in central Alabama. Latest surface analysis shows a deepening area of surface pressure in Louisiana into western Mississippi. With the continued approach of an upper-level trough, continued deepening of the surface low is anticipated through the overnight period. This mass response will increase theta-e advection into the western Florida Panhandle and Alabama helping to boost MLCAPE values 500-1500 J/kg by early evening. Observational trends in KDGX and KLIX VAD profiles have shown a large increase in low level hodograph curvature and SRH. These trends should continue as the trough shifts eastward. Guidance has suggested a marked increase in the low-level jet across much of Alabama during the 7-11 PM CDT time period. Given these expected favorable low-level shear parameters along with effective deep-layer shear of around 60 kts, organized convection with mid and low-level rotation appears likely. A tornado watch will be needed for this area. Aside from the tornado threat, strong winds fields will support a threat for damaging wind gusts as well.

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