919
ACUS03 KWNS 190730
SWODY3
SPC AC 190729

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0229 AM CDT Thu Sep 19 2024

Valid 211200Z - 221200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN THE SOUTHERN
HIGH PLAINS...

...SUMMARY...
Isolated severe thunderstorms are possible on Saturday afternoon to
early evening in the southern High Plains.

...Southern High Plains...
In advance of a southern-stream shortwave trough reaching the Four
Corners, a 50-65 kt 500-mb jetlet is forecast to eject over NM by
early evening Saturday. This will yield favorable deep-layer shear
for organized storms across eastern NM into parts of northwest TX.
Strengthening large-scale ascent within a low-level warm/moist
conveyor should overspread this region by Saturday morning. This
should yield early-period convection and renders moderate
uncertainty over the degree of destabilization by afternoon. Still,
with ample boundary-layer heating to the south of early-day
activity, a plume of at least weak-surface based buoyancy should
develop. Renewed afternoon to early evening thunderstorms should be
capable of producing at least isolated severe. Steep mid-level lapse
rates should be confined along and west of the Sangre de Cristo
Mountains, rendering further uncertainty over the intensity and
coverage of the severe threat. The eastern extent of the threat
should be curtailed by the confined buoyancy plume and decreasing
instability deeper into TX/OK.

...Lower/Mid-MO Valley to the Upper MS Valley...
A relatively complex and uncertain evolution to convective potential
is evident on Saturday afternoon and evening. This region will
largely remain within a low-amplitude mid-level ridge. This may
flatten somewhat in between a southern-stream shortwave trough in
the Southwest and a northern-stream trough over the southern Prairie
Provinces to along the ND/MN international border. In association
with the latter wave, a surface cold front should push southeast in
the north-central states. Guidance varies with the degree of
destabilization ahead of it, and especially with the spatial extent
of afternoon/evening convection. As such, a severe threat area has
not yet been delineated but may be warranted in later outlooks if
predictability increases.

..Grams.. 09/19/2024

$$