ACUS11 KWNS 141833
SWOMCD
SPC MCD 141833=20
ALZ000-MSZ000-ARZ000-LAZ000-142000-

Mesoscale Discussion 1041
NWS Storm Prediction Center Norman OK
0133 PM CDT Wed Jun 14 2023

Areas affected...far northeast Louisiana into central Mississippi

Concerning...Severe potential...Watch likely=20

Valid 141833Z - 142000Z

Probability of Watch Issuance...95 percent

SUMMARY...A significant severe-wind threat is developing across
portions of northeast LA into central MS ahead of an approaching bow
echo. A derecho may produce hurricane force wind gusts across the
region if the bow echo can maintain intensity and continue to grow
upscale. A Particularly Dangerous Situation Severe Thunderstorm
Watch will be issued soon.

DISCUSSION...A compact, intense bow echo is traversing the AR/LA
border and is rapidly moving southeast at around 50 kts. Though the
bow echo is nearly perpendicular to the radar beam, intense inbound
velocities depict the presence of a rear-inflow jet, likely driven
by a strong, deep cold pool. Furthermore, along a stationary
west-to-east surface boundary, an elongated corridor of impressive
overlapping buoyancy/shear is in place. At least mid 70s F surface
dewpoints, overspread by unseasonably steep mid-level lapse rates,
are supporting 5000+ J/kg SBCAPE. Regional VADs and mesoanalysis
depict hodographs with modest low-level curvature and very long
hodographs aloft, yielding 60+ kts of effective bulk shear.=20

The 12Z JAN observed sounding showed very dry air in the 850-500 mb
layer, along with 9 C/km lapse rates in this layer, which often
precede derecho-producing MCSs. Given the intensity of the
approaching bow echo, the presence of a dry 850-500 mb layer with
anomalously steep mid-level lapse rates, and the elongated corridor
of overlapping extreme instability/vertical shear, confidence is
increasing in the occurrence of a derecho. Widespread severe winds
are likely, along with several hurricane-force wind gusts. A few
tornadoes may also occur with mesovortices along and immediately
north of the apex of the bow echo. A Particularly Dangerous
Situation Severe Thunderstorm Watch will be needed to address the
severe threat.

..Squitieri/Thompson.. 06/14/2023

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!6_fcemhWuGzgP7JgNqkXMUhr6DBFFwf4GPqthmLwAqFkCPAEllxHcSohO_Nl58tWh5abRBMK7= vyVK-Jwc2OZfgJvBK4$ for graphic product...

ATTN...WFO...BMX...MOB...JAN...LZK...SHV...

LAT...LON 33319242 33479234 33599190 33609104 33469000 33318880
33118833 32868829 32448832 31978848 31658899 31589002
31759086 32139164 32349227 33319242=20


=3D =3D =3D
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