SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0752 AM CDT Mon May 23 2022
Valid 231300Z - 241200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS...
...SUMMARY...
Severe thunderstorms will be possible today into tonight across
parts of the southern Plains, with large hail, severe wind gusts,
and a tornado or two possible. Isolated damaging wind and a tornado
may occur across parts of the Southeast.
...Synopsis...
In mid/upper levels, broadly cyclonic flow will cover much of the
Rockies and Plains, as a series of shortwave perturbations
contribute to gradual amplification of a slowly eastward-moving
synoptic trough. On the southeastern fringe of that regime,
moisture-channel imagery indicates a weak southern-stream
perturbation over northeastern Chihuahua and far west TX, east of
another small trough over western Chihuahua. The leading feature
should move east-northeastward across southwest/west-central TX
today, with vorticity augmentation likely from convective processes.
That perturbation should reach eastern OK and east TX by 12Z
tomorrow. Meanwhile, behind the southern perturbation and over the
southern High Plains, height falls will continue as the synoptic
trough amplifies. By 12Z, the larger trough should extend nearly
over the spine of the Rockies from MT-NM, with a prominent vorticity
lobe over northeastern NM. Farther east, a deep-layer trough was
apparent over AL, with weak low-level circulation centered near MGM
at 11Z. This feature is forecast to move northeastward across
northern GA and the western Carolinas through the period, while
gradually deamplifying.
At the surface, 11Z analysis depicted a cold front over the Atlantic
east and south of New England, becoming quasistationary across
northern/western NC, southeastern TN and northern AL, then a slow-
moving cold front again over central MS, southern LA, and the
mid/upper TX coastal-shelf waters. A quasistationary to warm front
was drawn from there across south TX to a low near FST. A separate
low north of MGM should move northeast and merge with the frontal
zone through the day. The TX part of the front will move northward
and become diffuse, amid an intensifying, broad, low-level warm-
advection plume. A dryline should develop today over eastern NM,
along the western edge of the associated moisture return. Another
frontal zone will develop farther northeast by 00Z -- from the
northern part of a strengthening lee trough/low over northeastern NM
across the TX Panhandle and north TX. This boundary should pivot to
a position from east-central NM to north-central OK by 12Z.
...Southern Plains...
Isolated to scattered thunderstorms are expected to develop this
afternoon over the High Plains west of the Caprock, as well as over
a swath of weakly capped, moist boundary layer from the southeastern
Trans-Pecos/Big Bend regions to the Edwards Plateau and across the
northern Serranias Del Burro of Coahuila. The severe threat is not
well-focused east of the dryline, but with weak MLCINH and variable
large-scale lift aloft expected, a broad area will have the
potential for convective initiation and maintenance.
Large hail and isolated severe gusts will be the main concerns
during the first few hours of the convective cycle. Several
supercells are possible, given strong veering of flow with height,
and generally 35-45 kt effective-shear magnitudes. Tornado potential
appears very conditional and relegated to localized boundary/
storm-scale interactions, given the modest ambient hodographs. Some
of the diurnal activity may aggregate into at least a couple loosely
organized clusters or small MCSs into this evening, supported by
moisture advection/transport associated with a broad, strengthening
nocturnal LLJ. Such convection will offer predominantly a wind
threat while moving east of the Caprock, and across the
southwest/south-central TX region.
A combination of moist/theta-e advection and diurnal heating
(including heating of higher terrain from the Big Bend region into
Coahuila) will erode the cap today, and will contribute to favorable
buoyancy. By late afternoon, preconvective surface dew points in
the 50s F should be common from the Panhandles to the South Plains,
with 60s from the lower Pecos Valley region across the Edwards
Plateau, Hill Country, north TX, and southern OK. MLCAPE around
1000-1500 J/kg will be possible over the High Plains east of the
dryline, while values of 1500-2000 J/kg may develop prior to
convective passage from northwest to southwest TX. Convection
should weaken with eastward progress tonight over northwest
TX/southern OK, and near the I-35 corridor in central/south TX.
...Southeast...
Widely scattered to scattered thunderstorms are expected through
this evening, in a northeastward-shifting, low-level convergence arc
located east through south of the primary low/middle-level
circulation center and vorticity max. A marginal tornado threat is
apparent from embedded supercell(s)/mesovortices, and isolated gusts
near severe limits may be noted as well. The overall coverage and
magnitude of severe potential still appear isolated and marginal,
though mesoscale trends will be monitored for better-focused,
higher-probability potential within this swath.
The boundary layer should destabilize through the afternoon ahead of
the primary convergence arc, within a combination of low-level
theta-e advection and pockets of variably cloud-muted diurnal
heating. Although weak midlevel lapse rates will temper buoyancy
somewhat, moisture associated with surface dew points commonly in
the mid 60s to lower 70s F will contribute to MLCAPE around 500-1500
J/kg. Despite the slow weakening of the deep-layer trough, a
mesoscale belt of enhanced cyclonic flow in the 850-500-mb layer
will shift northeastward across GA and parts of the Carolinas
through this evening, just south through east of the main midlevel
vorticity lobe. This will overlie the main low-level convergence
zone, with enough low-level and deep shear to support sporadic
organization of associated quasi-linear convection into bows and
LEWPs. Occasional, mostly short-lived supercell structures may be
noted either within the main convective arc, or in discrete to
semi-discrete supercells to its east. Some backbuilding or
regeneration of convection is possible late this afternoon from
central GA toward southeastern AL and perhaps adjoining parts of the
FL Panhandle as well, though shear will be weaker over that area by
then.
..Edwards/Kerr.. 05/23/2022
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