SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0249 PM CDT Sat Apr 16 2022
Valid 162000Z - 171200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR SOUTHERN
ARKANSAS INTO NORTHEAST LOUISIANA...SOUTHERN MISSISSIPPI AND
SOUTHWEST ALABAMA....
...SUMMARY...
The corridor of greatest severe-thunderstorm concern today appears
to be from southern Arkansas to southeastern Alabama. More-isolated
and/or marginal severe weather is possible elsewhere from parts of
south Texas to the coastal Carolinas, as well as across northern
Utah into southeast Idaho.
Trimmed the northern periphery of the marginal delineation where
instability is now limited north of the front and any additional
development later tonight should remain sub-severe. No changes were
necessary for the general slight risk area. Trimmed the tornado
probabilities southwest to areas ahead of the southwestward moving
outflow boundary. However, elevated hail remains possible northeast
of this boundary. Therefore, kept the 15 percent hail probabilities
across this region.
Elsewhere, the forecast remains on track.
..Bentley.. 04/16/2022
.PREV DISCUSSION... /ISSUED 1126 AM CDT Sat Apr 16 2022/
...Synopsis...
Late-morning regional radar mosaics show ongoing thunderstorms along
an outflow boundary from western AR into the Ark-La-Miss region.
This activity will continue to sag south/southeastward through the
day in tandem with the outflow boundary, posing a severe wind/hail
threat. While the highest severe weather potential will be
associated with storms along this outflow, thunderstorms developing
a cold front draped from the mid-Appalachians into southern
OK/northern TX will pose a more isolated severe risk. Further west,
an upper-level wave moving across central CA is expected to push
into the inter-mountain West by this afternoon. Thunderstorms
developing ahead of this wave/along a cold front may be capable of
severe winds.
...Southern AR into southern MS/AL...
Over the past hour, most remote sensing observations suggest that
the ongoing thunderstorms along the outflow boundary have been
gradually weakening with predominantly sub-severe wind/hail
reported. Despite mostly cloud skies ahead of this line,
temperatures have begun to warm into the mid to upper 70s, which is
supporting gradual destabilization with MLCAPE values increasing to
near 1500 J/kg. Moderate buoyancy (MLCAPE values to near 2000 J/kg)
is expected to be in place across northern LA and southern
MS/southeast AL by late afternoon, leading to a re-intensification
by this afternoon. Surface to 850 mb convergence along the boundary
combined with boundary-parallel deep-layer shear vectors should
support thunderstorm clusters to mainly linear modes, potentially
with a few bowing structures. A weak MCV is noted in the Ark-La-Miss
region as of 1600 UTC, which may intensify and organize into such a
bowing structure by the early afternoon hours. Damaging winds are
the primary concern, but elongated hodographs above 3 km will
support an attendant severe hail risk. Veering in the lowest 1 km
may support a brief tornado threat for any surface-based storm
rooted on the outflow boundary.
Later tonight across central AR, scattered elevated thunderstorms
are likely as warm advection increases atop the residual cold pool.
While mid-level lapse rates will be somewhat limited, sufficient
instability and deep-layer shear may support a few strong to severe
storms capable of severe hail.
...Southern to eastern TX...
Isolated to scattered thunderstorm development is expected along the
cold front by mid to late afternoon as daytime heating erodes
mixed-layer inhibition noted in morning soundings. Despite weak
low-level flow, strong winds aloft combined with 7-8 C/km lapse
rates will support a few organized storms with an attendant
hail/wind risk.
...Southeast to the Carolinas...
Weak convection is ongoing across GA into SC ahead of the surface
cold front. This activity will continue to meander towards the coast
through the afternoon hours. Intensification and additional
convection is probable through the afternoon hours as modest daytime
heating occurs and supports some boundary-layer destabilization.
Somewhat poor mid-level lapse rates and modest forcing for ascent
will limit the overall severe potential, but a few robust updrafts
are possible given adequate deep-layer shear.
...Utah...
Steep mid-level lapse rates are noted in the 12 UTC SLC RAOB, which
will likely be maintained for much of the day as temperatures aloft
fall and mid-level moisture increases ahead of the approaching
upper-level wave. This will support isolated to scatted
thunderstorms across the inter-mountain West by late afternoon. A
dry, well-mixed boundary layer across northwest UT into southeast ID
will support a microburst potential with strong to severe winds.
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