SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0649 AM CST Sun Nov 03 2024
Valid 031300Z - 041200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
SOUTHERN PLAINS...
...SUMMARY...
Multiple rounds of strong-severe thunderstorms are possible today
through tonight over parts of the southern Plains. Tornadoes,
damaging winds and large hail are possible.
...Synopsis...
A full-latitude, mid/upper-level trough will move slowly eastward
across the western CONUS, while evolving into a split-flow regime.
The more-influential southern section of the trough is expected to
amplify considerably as a shortwave perturbation and associated
speed max -- now located over the southern Great Basin -- pivot
through the base of the synoptic trough. By 00Z, the shortwave
trough should dig southeastward to southern AZ and adjoining
portions of Sonora. A leading vorticity lobe should eject to
eastern NM by the end of the period, within a broader area of
enhanced cyclonic flow extending across AZ, northern Chihuahua, and
west TX. A 500-mb low may form by 12Z tomorrow near the center of
that curvature, across central NM. In response to these
developments, strengthening/difluent flow and height falls will
spread eastward ahead of the synoptic trough -- across the southern
Plains and west TX.
At the surface, 11Z analysis showed an outflow boundary fronting an
MCS from the western Ozarks southwestward to northwest TX. The
boundary should shift into AR and southeastern OK through the
remainder of the morning before stalling, while the segment from the
Red River region southwestward across the Big Country and northern
Permian Basin already has become very slow-moving to stationary.
The boundary should retreat northward through the period, with
uncertainty remaining as to how far and with what specific timing,
given a substantial cold pool evident across central/western OK and
the South Plains/Panhandle region. A dryline -- initially analyzed
over southeastern NM and far west TX -- should shift eastward to the
southern Panhandle/south Plains and across the Permian Basin through
the afternoon. A surface low initially near the central CO/KS
border should move northeastward to central/north-central NE by 00Z,
with cold front southwestward to another low in southeastern CO. A
lee trough and more diffuse dryline will take shape and move
eastward across the central High Plains into western KS, before
being overtaken by the cold front.
...Southern/central Plains...
A QLCS began the period arching from the western Ozarks across
southeastern OK and parts of north-central/northwest TX. The
central/northern part of this complex is outrunning favorably
unstable inflow and should continue a broader weakening trend
through the remainder of the morning. Meanwhile the southern part
-- over southern OK and north TX -- has more buoyancy and still-
favorable vertical shear to its east and southeast. However, that
segment of convection is decelerating and non-severe. It also is
located behind the associated outflow boundary, which is exhibiting
anafrontal characteristics.
As it retreats northward across the Red River Valley today into this
evening, the outflow boundary should become more diffuse, with a
loosening baroclinic gradient. This will occur amidst broader,
synoptically driven theta-e advection. Meanwhile this feature and
the dryline to its southwest should focus additional widely
scattered to scattered thunderstorm development. Convection also
may form in the warm/moist sector east of the dryline and south of
the outflow boundary, given the lack of a substantial EML and
typically accompanying capping. With favorable low-level and deep-
layer shear expected, supercells and bowing QLCS configurations are
possible, offering all severe hazards (hail, gusts, tornadoes). The
greatest potential for relatively discrete/sustained supercells
appears to be near the retreating boundary in northwest TX and parts
of southern/central OK, and significant-severe hail may occur with
some of that convection.
Multiple convective episodes are expected from the afternoon's
greatest boundary-layer heating through late overnight, when
large-scale ascent will increase again due to both warm advection/
LLJ processes and DCVA/cooling aloft ahead of the approaching
trough. These will overlap rich low-level moisture (surface
dewpoints near and south of the boundary in the mid 60s to low 70s
F). By late overnight, airmass recovery may extend into much of
western/central OK, supporting another round of severe potential
there. A more-concentrated mesoscale-focused severe threat
(especially for tornadoes and/or severe gusts) may develop today
into this evening near the residual boundary, but uncertainty on
convective mode/coverage remains too large to assign greater
unconditional probabilities at this cycle.
Farther north, diurnally destabilized but convectively processed
trajectories will temper the overall threat into the central Plains,
along/ahead of the dryline and cold front. However, a few strong-
severe thunderstorms are possible, mainly this afternoon into early
evening.
..Edwards/Mosier.. 11/03/2024
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