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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0750 AM CDT Sat Apr 16 2022

Valid 161300Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE ARKLATEX
REGION TO PARTS OF SOUTHERN AL...

...SUMMARY...
The densest corridor of severe-thunderstorm potential today appears
to be from southern Arkansas to southern Alabama.  More-isolated
and/or marginal severe weather is possible elsewhere from parts of
south Texas to the coastal Carolinas.

...Synopsis...
Predominantly zonal flow will prevail in mid/upper levels over most
of the CONUS, south of a synoptic trough over the Northeast and QC,
and a strong shortwave trough that will move eastward from the
Pacific Northwest across the northern Rockies.  Another well-defined
shortwave trough -- loosely phased with the Northwest feature at
this time -- is apparent in moisture-channel imagery approaching the
central/northern CA coastline.  This perturbation should outrun the
northern-stream one and move eastward to parts of the central/
southern High Plains by the end of the period.  Meanwhile,
convectively induced/enhanced, cyclonic vorticity lobes now over AL
and AR will move eastward to southeastward across the Southeast
today.

Surface 11Z analysis showed a cold front across parts of western TN,
central AR and eastern OK, through a frontal-wave low between
FTW-SPS, then across northern parts of the Permian Basin region of
west TX.  The low should shift southeastward to east TX today, with
the front reaching south-central/southwest TX by 00Z.  By 12Z, a
weaker version of the low should be located over northern LA, with
cold front across southeast/deep south TX and eastern/northern
Coahuila.  An outflow boundary from southern AL across northern MS
should sag southward over MS through the day.

...AR/MS/LA/AL...
A corridor of damaging-wind and large-hail potential, with a tornado
also possible, exists ahead of a strong-severe thunderstorm co*plex
now over portions of AR.  For near-term considerations, refer to SPC
watch 134 and related mesoscale discussions.

This activity and/or additional, surface-based severe convection
should be focused today along and south of the outflow boundary and
well east of the surface low.  Preconvective low-level vorticity/
lift will be maximized along the boundary, with theta-e/instability
diminishing to its north.  To its south, rich low-level moisture,
and limited/gradual diurnal heating beneath cloud cover, should
remove most MLCINH and boost MLCAPE to around 1500-2000 J/kg. 
Meanwhile, 40-45 kt effective-shear magnitudes should be co*mon,
supporting mixed modes (messy/HP supercells, bowing QLCS segments
and multicell clusters).

...TX MRGL area...
Isolated thunderstorms may develop along the front this afternoon,
and maintain access to a favorably moist-heated warm sector long
enough to produce severe gusts and large hail.  Any relatively
discrete convection that matures could beco*e supercellular, at
least for a short time, and offer very large/damaging hail.  As
such, a conditional significant-severe hail threat exists; however,
concerns over low convective coverage and limited duration preclude
assigning an unconditional 10%/significant-hail area.  Forecast
soundings suggest a brief period late this afternoon when minimal
MLCINH and steep low-level lapse rates co*bine with surface dew
points in the upper 60s to low 70s F, to yield 1000-2000 J/kg
MLCAPE.  Though low-level flow will be weak, effective-shear
magnitudes around 40-50 kt should be co*mon.  Forecast moisture
profiles suggest mixing/entrainment may be a hindrance for
convection, as can be frontal undercutting.

...Eastern MRGL area...
The eastern extent of diurnal development associated with the AL MCV
and associated outflow/differential-heating boundaries is uncertain,
with weaker low-level shear and midlevel lapse rates expected. 
Still, portions of southeastern AL, GA and the eastern/southern
Carolinas may experience isolated severe potential -- southeast of
those boundaries and the front -- and perhaps along sea-breeze
boundaries as well.  Modest low/middle-level flow will limit
vertical shear overall, except where locally enhanced along
favorably oriented boundaries, with effective-shear magnitudes
co*monly in the 25-40-kt range.  Somewhat stronger deep/cloud-layer
shear may exist over the Carolinas part of the area.  Peak/
preconvective MLCAPE generally should reach the 500-1200 J/kg range
through the afternoon.

..Edwards/Smith.. 04/16/2022