ACUS48 KWNS 140844
SWOD48
SPC AC 140842

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CDT Sat Sep 14 2024

Valid 171200Z - 221200Z

...DISCUSSION...
...D4...
Severe potential may be maximized on D4/Tuesday, but persistent
predictability concerns preclude a 15 percent highlight.

A mid-level low centered the ID/NV/UT border area at 12Z Tuesday
should advance north-northeast towards the MT/AB/SK border area by
12Z Wednesday. Guidance has improved consistency with this track.
But models remain inconsistent with the amplitude of the meridional
mid-level jet to the east of the low, and spatial/temporal spread
appears to have increased with evolution of surface cyclogenesis
over the northern High Plains. It is plausible that a meso-alpha
scale corridor of 15 percent severe probabilities may be warranted
in later outlooks, somewhere in the eastern MT/WY to western Dakotas
vicinity.

The large spread in guidance with the development of a near-coastal
subtropical/tropical cyclone on D3 renders minimal predictability
for D4 severe potential in NC and the Lower Mid-Atlantic region.

...D6-8...
Latest guidance has trended towards a slower, positive-tilt
large-scale trough evolution over the West, as the next upstream
shortwave impulse digs back into the Southwest. A moderate mid-level
southwesterly flow regime and persistent moderate to well-above
normal temperatures may yield daily bouts of low-probability severe
from the south-central High Plains to the Upper Midwest. Despite
typical predictability concerns in this time frame, overall setup
appears unlikely to support a synoptically evident severe episode.

..Grams.. 09/14/2024

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