MD 1041 CONCERNING SEVERE POTENTIAL…WATCH LIKELY FOR FAR NORTHEAST LOUISIANA INTO CENTRAL MISSISSIPPI
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
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.
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 www.spc.noaa.gov 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
