ACUS01 KWNS 150546
SWODY1
SPC AC 150544

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1144 PM CST Sat Dec 14 2024

Valid 151200Z - 161200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN FAR NORTH TX
TO NORTHWEST AR...

...SUMMARY...
A low-end severe threat, primarily in the form of marginal hail, is
possible tonight across a portion of the Red River Valley into the
southern Ozark Plateau.

...Synopsis...
A shortwave trough will progress from the northern Great Basin into
the Upper Midwest by tonight, with low-amplitude impulses moving
east across the Southwest. Primary surface cyclone will deepen as it
tracks from the Black Hills to the Lake of the Woods vicinity. An
occluded/cold front will arc south into the Ozarks by tonight, with
trailing portion extending southwestward in OK/TX.

...North TX to the Lower OH Valley...
A broad, low-level warm/moist conveyor will become established from
the Lower Rio Grande Valley northeastward into the Lower OH Valley
through tonight. Low-amplitude shortwave ridging should preclude
appreciable thunderstorm development until late evening. A swath of
elevated storms is expected to blossom into the overnight, from
parts of eastern OK into the Lower OH Valley as weak mid-level
height falls overspread the gradually moistening corridor. The
southwest extent of this regime into far north TX should contain
surface-based parcels, although low-level lapse rates may be poor.

Nearly unidirectional southwesterly wind profiles are progged across
much of the warm conveyor, ahead of the similarly oriented cold
front. M-shaped type hodographs are anticipated from southeast OK
southwestward, with weakness in the flow around 700 mb, where MUCAPE
appears largest from 1000-2000 J/kg. Non-FV3 members of the 00Z HREF
and available NSSL-MPAS runs indicate minimal 2-5 km UH signal.
Given these factors, storm mode will probably become messy early in
the convective development life cycle. Still, conditional potential
exists, amid an adequate combo of effective bulk shear and MUCAPE,
for a few deeper updrafts to acquire transient rotation, with an
associated marginally severe hail threat. Where exactly that
transitions to purely small hail magnitudes is uncertain with
northeast extent, as mid-level lapse rates should be more muted and
buoyancy will be less.

..Grams/Lyons.. 12/15/2024

$$

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