SPC MD 1364


MD 1364 Image

Mesoscale Discussion 1364
NWS Storm Prediction Center Norman OK
1235 PM CDT Fri Jul 31 2020

Areas affected...northern Louisiana into central and northern

Concerning...Severe potential...Watch likely 

Valid 311735Z - 311900Z

Probability of Watch Issuance...80 percent

SUMMARY...Thunderstorm intensity and coverage is expected to
increase this afternoon. Isolated strong-to-severe thunderstorm wind
gusts and a brief tornado will be possible. A severe thunderstorm
watch will likely be needed soon.

DISCUSSION...Clear skies have allowed surface temperatures to warm
into the upper-80s to low-90s F this afternoon across portions of
northeast Louisiana into central Mississippi. Here, the combination
of strong surface heating and widespread moisture (surface dewpoints
in excess of 70F) will provide an airmass conducive for the
development of thunderstorms this afternoon. In fact, recent visible
satellite imagery shows agitating cumulus developing/persisting
across the area. In addition to the potential for thunderstorm
development within the hot, humid airmass, as suggested by satellite
imagery, a surface front across northwest Louisiana into southeast
Arkansas will continue to push south and east through the afternoon.
This surface boundary will provide an additional focus or
thunderstorm development.

This region is on the southern periphery of the better deep-layer
flow, yielding deep-layer shear of 30-40 knots despite westerly
low-level winds. This combined with most-unstable CAPE values
approaching 4000 J/kg across central Mississippi, will yield the
potential for organized multi-cell thunderstorms, potentially
evolving into short lines/bows, capable of producing isolated severe
wind gusts. A brief tornado cannot be ruled out given the very
unstable airmass and the presence of a surface boundary, nor with
any transient supercell structure that may develop with in the
vicinity of sustained backed low-level flow.

Given the environment across the region and the expected number of
thunderstorms, a Severe Thunderstorm Watch will likely be needed
across portions of the area during the afternoon.

..Marsh/Bunting.. 07/31/2020

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


LAT...LON   33229134 34458931 32238877 31659296 32289402 33229134 

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