SPC Mesoscale Discussion: Severe Potential… Watch Unlikely

SUMMARY…Isolated strong to damaging winds and perhaps a brief tornado may occur this morning with a line of thunderstorms moving eastward. Watch issuance remains unlikely in the short term.

DISCUSSION…A line of low-topped convection has recently consolidated across parts of eastern MS and far southeastern LA ahead of a surface cold front. Strong low-level shear is present over this region, as a 40-50 kt southwesterly low-level jet noted on the 12Z sounding from LIX is forecast to move slowly eastward this morning. 0-1 km shear around 30 kt has been noted on recent VWPs from the KLIX radar, and effective SRH around 250-335 m2/s2 should support some low-level rotation with the strongest updrafts embedded within the line. The main limiting factors which will probably preclude a greater severe risk are weak instability and generally modest low-level moisture ahead of the line of storms. Surface dewpoints remain in the low to mid 60s across this region as of 12Z, with upper 60s dewpoints confined to the southern LA Coast and vicinity. Widespread cloudiness will tend to limit diurnal heating, and low-level lapse rates will likewise struggle to steepen this morning across western/central AL. Accordingly, MLCAPE is expected to remain at or below 500 J/kg with poor mid-level lapse rates present across this region. Still, an isolated strong to damaging wind gust could occur with any downdraft along/ahead of the line. A brief tornado also cannot be ruled out given the strong low-level shear. Regardless, weak instability should keep the overall severe threat marginal, and watch issuance remains unlikely at this time.

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