SPC Nov 2, 2024 1300 UTC Day 1 Convective Outlook

[NorthGeorgiaWX]

SPC 1300Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0746 AM CDT Sat Nov 02 2024

Valid 021300Z - 031200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE PERMIAN
BASIN AND SOUTH PLAINS INTO PORTIONS OF OKLAHOMA...

...SUMMARY...
Scattered strong to severe storms will be possible later today and
tonight, primarily from the Permian Basin and South Plains into
southwest Oklahoma during the late afternoon and early evening.

...Synopsis...
In mid/upper levels, a full-latitude trough is located from BC down
the West Coast States to Baja.  A series of accompanying shortwaves
and speed maxima -- predominantly remaining behind the height axis
-- will contribute to the trough's eastward shift across the western
parts of the CONUS and Canada through the period.  By 12Z tomorrow,
the trough should extend from the Mackenzie River Valley of
northwestern Canada, across the length of AB, to western MT, the
central/eastern Great Basin, western/central AZ, Sonora, and
southern Baja.  An extensive fetch of southwest flow aloft and
height falls will precede the trough over the U.S Rocky Mountains
and Great Plains. 

In the slower southern part of that southwest flow, a basal
shortwave trough was evident in moisture-channel imagery over parts
of AZ and the eastern Sonora/western Chihuahua area.  This feature
is augmenting the more diffuse, large-scale support from the
synoptic trough for the warm/moist advection regime and related,
extensive band of thunderstorms and precip observed from southern NM
to southern KS.  This perturbation should reach eastern NM and far
west TX by 00Z, then perhaps with convective vorticity enhancement,
eject northeastward into portions of KS and western OK overnight. 

At the surface, 11Z analysis showed a cold front over the Atlantic
well offshore from the Mid-Atlantic region, becoming quasistationary
across northern FL, the north-central Gulf Coast vicinity and
southeast TX, then a warm front over central/northwest TX.  The
western segment of this boundary should move slowly and diffusely
northeastward today into OK as a warm front. 

...Southern High Plains to portions of OK...
Scattered to numerous thunderstorms in a southwest/northeast-
oriented band should shift eastward over the outlook areas today
into this evening, offering mainly isolated damaging gusts and
marginally severe hail, with a low-end threat for embedded/QLCS
mesovortex tornadoes.  Hail and tornado potential will be greatest
farther southwest today over parts of west TX and extreme
southeastern NM.

Available/modified RAOB data and objective SPC mesoanalyses indicate
effective inflow parcels already are surface-based south and west of
the effective warm front, across western OK, northwest TX, and the
South Plains to the Permian Basin.  This should remain the case
throughout today, as muted diabatic heating and theta-e advection
slowly destabilize the warm sector south of the convective boundary.
 This will combine with mid 60s to low 70s F surface dewpoints,
offsetting modest midlevel lapse rates enough to support
peak/preconvective MLCAPE ranging from around 2000 J/kg over
southeastern NM and the South Plains/Permian Basin regions, to
around 500 J/kg near the diffuse warm front in central OK.  The
approaching synoptic and shortwave troughs will tighten height
gradients enough to boost deep shear, contributing to around
35-45-kt effective-shear magnitudes.  Meanwhile, low-level
hodographs should exhibit enough size/curvature and lowest-km RH to
suggest at least marginal tornado potential. 

While the parameter space (as sampled by various model soundings) 
will be favorable for the full range of severe hazards in and near
the "slight risk" corridor today, a somewhat anafrontal character to
the convective band is expected, given that it will be nearly
parallel to the flow aloft and slowly progressive due to quasi-
linear outflow effects.  Sustained and/or discrete supercell
potential appears greatest near the southern end of the regime over
the Permian Basin region, where instability should be greatest today
amid favorable shear, thereby relatively maximizing overall
probabilities for tornadoes and large to significant-severe (2+
inch) hail.

..Edwards/Mosier.. 11/02/2024

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