Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 201913
SWOMCD
SPC MCD 201912
ALZ000-MSZ000-LAZ000-202045-

Mesoscale Discussion 0801
NWS Storm Prediction Center Norman OK
0212 PM CDT Sat May 20 2017

Areas affected...Portions of LA...much of MS...and western/central
AL

Concerning...Severe potential...Watch unlikely

Valid 201912Z - 202045Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated strong/gusty wind threat will persist through
the remainder of the afternoon. Watch issuance is unlikely.

DISCUSSION...Latest visible satellite imagery shows an outflow
boundary moving southeastward across western MS, and multiple
clusters of convection have developed across eastern MS and
western/central AL in a low-level warm air advection regime. Outflow
from thunderstorms across eastern MS is moving westward, and
additional convection along these converging outflow boundaries will
likely occur over the next several hours across much of central MS.
A moist low-level airmass and diurnal heating have resulted in
MLCAPE generally ranging from 1500-2500 J/kg across the discussion
area, even though mid-level lapse rates remain modest (5.5-6.5 C/km
in the 700-500 mb layer).

With the primary upper trough/low located across the central Plains
and far to the northwest, large-scale forcing for ascent and
stronger mid-level winds will be mostly displaced to north of this
region. Still, some veering of winds with height present on recent
DGX/GWX VWPs are supporting around 30 kt of effective bulk shear,
and isolated instances of strong to locally damaging winds may occur
with the strongest cores through the remainder of the afternoon.
Current expectations are for thunderstorms to remain mostly
disorganized, and the overall severe weather threat will likely
remain too isolated/marginal to warrant watch issuance.

..Gleason/Weiss.. 05/20/2017

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

ATTN...WFO...BMX...HUN...MOB...MEG...JAN...LIX...LCH...

LAT...LON   34958817 34948740 34898664 33218655 32568696 31528792
            30698973 30379075 30359116 30859206 32519135 33389036
            34208985 34888874 34958817




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