Severe Storm Outlook Narrative (AC)
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ACUS11 KWNS 182118
SPC MCD 182118

Mesoscale Discussion 1771
NWS Storm Prediction Center Norman OK
0318 PM CST Sat Nov 18 2017

Areas affected...Western and Middle TN...northern MS and northern AL

Concerning...Severe potential...Watch possible

Valid 182118Z - 182315Z

Probability of Watch Issuance...40 percent

SUMMARY...A few severe wind gusts will remain possible across Severe
Thunderstorm Watch 517 through 01Z.  In addition, some risk for
strong/severe gusts will exist south of the watch area over northern
portions of MS and AL. Radar and storm report trends will be
monitored and a local watch extension or a new Severe Thunderstorm
Watch may be needed.

DISCUSSION...The southward extension of a line of strong/severe
thunderstorms extended from Stewart County TN southwest across
northwest MS at 2110Z.  Thus far, storms have remained mostly below
severe limits across WW 517, however recent radar trends show a
solidifying line with a more pronounced leading edge reflectivity
gradient.  Thus, in the presence of weak surface-based instability
and strong low-mid-level southwesterly wind fields the risk for
widely scattered damaging gusts should continue through 01Z as the
line moves towards Middle TN.

Farther south, a few breaks in cloud cover have allowed slightly
greater surfaced-based instability across northern MS, where storms
have been gradually strengthening since 20Z. Low-mid level wind
fields will be supportive of some severe potential in this area, and
a local watch extension may be needed across southern portions of
the WFO Memphis County Warning Area.  Although cloud cover remains
well established farther east across northern AL, at least some risk
for strong/severe gusts may develop as the fast-moving line of
storms progresses east through this evening aided by strong frontal

..Bunting/Hart.. 11/18/2017

...Please see for graphic product...


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