MD 1831 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR EXTREME SOUTHEASTERN LA AND SOUTHERN MS

Mesoscale Discussion 1831
NWS Storm Prediction Center Norman OK
1141 PM CST Thu Dec 03 2020

Areas affected...Extreme southeastern LA and southern MS

Concerning...Severe potential...Watch unlikely 

Valid 040541Z - 040715Z

Probability of Watch Issuance...5 percent

SUMMARY...Weakly rotating storms will be possible from extreme
southeastern LA into extreme southern MS, but severe storms are not
anticipated.

DISCUSSION...A gradual increase in convection has been observed the
past 1-2 hours from southeastern LA into extreme southern MS, near a
weak surface cyclone and cold front.  There has been some indication
of a modest increase in larger-scale ascent the past few hours per
subtle moistening in water vapor imagery, downstream from a
positive-tilt trough from southwest TX to the mid MS Valley.  Local
VWPs show sufficient deep-layer and low-level shear for rotating
storms in the narrow warm sector across extreme southeastern LA into
coastal MS.  However, the greater moisture return and slightly
larger buoyancy (MUCAPE near 500 J/kg) is occurring atop a shallow,
somewhat stable near-surface layer.  Given the slightly elevated
nature of the convection, and the otherwise marginal buoyancy and
vertical shear environment, the threat for severe storms still
appears minimal.

..Thompson.. 12/04/2020

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MOB...JAN...LIX...

LAT...LON   29868886 29538931 29358990 29469019 30088997 30628973
            31108943 31098890 30758860 30478850 29868886 

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