MD 0644 CONCERNING SEVERE THUNDERSTORM WATCH 176… FOR EASTERN ARKANSAS TO NORTHERN MISSISSIPPI AND NORTHWEST ALABAMA
Mesoscale Discussion 0644
NWS Storm Prediction Center Norman OK
0657 PM CDT Thu Apr 27 2023
Areas affected...Eastern Arkansas to northern Mississippi and
northwest Alabama
Concerning...Severe Thunderstorm Watch 176...
Valid 272357Z - 280200Z
The severe weather threat for Severe Thunderstorm Watch 176
continues.
SUMMARY...The threat for severe hail and damaging winds continues
across much of WW 176, but the greatest near-term risk will reside
across eastern Arkansas into northwest Mississippi and far eastern
Mississippi to far west/northwest Alabama.
DISCUSSION...Scattered convection continues to erupt immediately
ahead of a mid-level vorticity maximum traversing across central AR.
This zone of focused ascent, combined with a favorable thermodynamic
and kinematic environment, has supported splitting supercells,
including a more prominent/robust cell across Arkansas/Monroe
counties that has remained relatively isolated. These cells will
continue to pose a large hail threat for the next 1-2 hours as they
move towards the apex of the MLCAPE axis across northwest MS.
However, long-term trends are somewhat uncertain given consolidating
convection along an outflow boundary to the west of the more
discrete activity, and the propensity for storm
interactions/amalgamating outflows with time within the focused zone
of ascent. Such upscale growth may favor an increasing damaging wind
threat, but weak low-level shear (around 20-25 knots in the 0-3 km
layer) sampled by regional VWPs casts uncertainty onto this
scenario.
To the east along the MS/AL border, a pair of long-lived supercells
with a history of 1-1.75 inch hail will begin to gradually meander
into the periphery of the higher mixed-layer buoyancy as they
migrate into western AL. However, the isolated nature of the
convection combined with 40-45 knots of effective bulk shear
downstream should help maintain storm intensity and the associated
large hail threat for the next few hours. Elsewhere across WW 176,
environmental parameters remain conducive for organized convection,
but additional CI is uncertain. The most likely location for
near-term CI appears to be across northwest MS where the GOES day
cloud phase RGB and low-level water vapor imagery shows shallow
convective towers, but robust convective initiation remains
uncertain given the onset of diurnal cooling.
..Moore.. 04/27/2023
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BMX...HUN...MOB...MEG...JAN...LZK...
LAT...LON 33429120 33699189 34499215 35239203 35569137 35669044
35428916 34868835 34138728 33878712 33548705 33138722
32758762 32398807 32158870 32248922 32498947 33429120
