ACUS48 KWNS 310923
SWOD48
SPC AC 310922

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0322 AM CST Tue Dec 31 2024

Valid 031200Z - 081200Z

...DISCUSSION...
Expansive ridging is forecast to gradually shift from the Plains
into the MS Valley and Southeast on D4/Friday, with stable
conditions prevailing.

A shortwave trough is expected to progress from the western Great
Basin through the Four Corners and into central/southern High Plains
on D5/Saturday, continuing eastward across central/southern Plains
and Mid/Lower MS Valley on D6/Sunday. Surface cyclogenesis appears
probable over the southern High Plains on D5/Saturday ahead of the
approaching shortwave, with a warm sector characterized by mid 60s
dewpoints likely to precede the resulting surface low and attendant
cold front. Thunderstorms are possible from central TX/OK eastward
through the Lower MS Valley on D6/Sunday, as the cold front
interacts with the moderately moist and buoyant air within the warm
sector. Deep-layer vertical shear is expected to be strong enough to
support organized storms (i.e. greater than 40 kt from 0-6 km).

Mid/upper level pattern is similar between the EPS and GEFS, but the
surface pattern has notable differences, with most GEFS members
favoring a slower and more southerly track to the surface low. This
is matched by the deterministic runs of the ECMWF and GFS, while the
Canadian splits the difference. Even though some severe appears
probable, these differences limit the forecast confidence, making it
difficult to ascertain the most likely corridor for severe
thunderstorms. Additionally, all of the deterministic guidance
continues to show notable run-to-run variability. All of these
factors combined with the extended range of the possible severe
(i.e. Day 6) result in too much uncertainty to delineate any risk
areas with this outlook.

The risk for thunderstorms will likely continue along the Gulf Coast
on D7/Monday as this system continues eastward. By D8/Tuesday, cold
and dry conditions are anticipated across the entire CONUS.

..Mosier.. 12/31/2024

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