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ACUS11 KWNS 271626
SPC MCD 271626

Mesoscale Discussion 0342
NWS Storm Prediction Center Norman OK
1126 AM CDT Mon Mar 27 2017

Areas affected...Northeast Arkansas...Far Southeast
Missouri...western and central Tennessee...southwestern and
south-central Kentucky

Concerning...Severe potential...Watch possible

Valid 271626Z - 271900Z

Probability of Watch Issuance...60 percent

SUMMARY...A severe threat appears likely to develop by early
afternoon across parts of the mid Mississippi Valley extending
eastward into south-central Kentucky and middle Tennessee. As cells
gradually intensify, wind damage and isolated large hail will be
possible. WW issuance will may be needed by 18Z across the region.

DISCUSSION...The latest surface analysis shows a surface low in
southwest Missouri with a cold front located southwestward from the
low. A warm front extends eastward from the surface low across
southern Illinois and west-central Kentucky. A line of thunderstorms
is ongoing in northeastern Arkansas located along a gradient of
low-level moisture oriented from west southwest to east northeast.
Moderate instability appears likely to develop along this corridor
over the next few hours. The line of storms is also located just
ahead of a shortwave trough on the southeast side of a pronounced
vorticity max. As the shortwave trough moves eastward, strong
large-scale ascent and continued surface heating will provide
support for a gradually increase in convective coverage.

In addition, the RAP is analyzing a mid-level jet from northwest
Mississippi extending northeastward into western Kentucky. This
feature is helping to create moderate deep-layer shear profiles with
0-6 km shear in the 35 to 40 kt range as evidenced by the Paducah
and Nashville WSR-88D VWPs. The wind shear environment should be
favorable for severe thunderstorm development with bowing line
segments and supercells both possible. The current thinking is that
the line of storms in northeast Arkansas will gradually expand in
length from north to south. The line should obtain a severe threat
by early afternoon as it moves across northwest Tennessee and
western Kentucky. Additional thunderstorms with a wind damage and
isolated large hail threat may develop ahead of the line from
northern Mississippi into western and middle Tennessee.

..Broyles.. 03/27/2017

...Please see for graphic product...


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