ACUS02 KWNS 120602
SWODY2
SPC AC 120600

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Mon Aug 12 2024

Valid 131200Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE EASTERN GREAT BASIN INTO THE NORTHERN/CENTRAL ROCKIES AND
ADJACENT HIGH PLAINS...AND ACROSS PARTS OF SOUTH CAROLINA AND VICINITY...

...SUMMARY...
Isolated severe thunderstorms appear possible Tuesday across parts
of the eastern Great Basin into the northern/central High Plains, as
well as portions of South Carolina and vicinity.

...Eastern Great Basin to the Northern/Central High Plains...
Upper ridging will remain over much of the Plains on Tuesday, while
a mid-level shortwave trough develops northeastward from the
interior Pacific Northwest across the northern Rockies and adjacent
High Plains. Modest low-level mass response ahead of this shortwave
trough should encourage the development/sharpening of a weak surface
low and associated lee trough extending southward along much of the
length of the northern/central High Plains. Northward advance of
low-level moisture is expected across these areas, along and east of
the lee trough. Steepened mid-level lapse rates and daytime heating
of this moistening airmass should support moderate instability
developing by late Tuesday afternoon.

Although mid-level flow is not forecast to be overly strong in
association with the mid-level shortwave trough, gradual veering and
modest strengthening of the wind field with height through mid/upper
levels should foster sufficient deep-layer shear for some
thunderstorm organization. An isolated threat for hail and severe
winds should exist with any robust cores that can develop along the
length of the lee trough and subsequently spread eastward Tuesday
afternoon through evening. Confidence in a more focused area of
severe potential remains too low to include greater severe
probabilities at this time.

There also appears to be some chance for stronger thunderstorms to
occur across the eastern Great Basin into parts of the
northern/central Rockies. While low-level moisture will generally be
more limited compared to the High Plains, sufficient instability and
deep-layer shear to support modestly organized convection are
forecast. Isolated hail and strong to severe wind gusts may occur
with this high-based activity as it spreads east-northeastward
through Tuesday afternoon and early evening. Therefore, the Marginal
Risk has been expanded westward to include more of WY, southern MT,
eastern ID, and northern/eastern UT based on latest guidance trends.

...South Carolina and Vicinity...
As a mid/upper-level trough persists over the eastern states, some
enhancement to west-northwesterly winds will occur across parts of
the OH/TN Valleys into the Carolinas and Southeast on Tuesday.
Deep-layer shear should be strong enough for modestly organized
convection. But, poor lapse rates aloft may tend to limit
instability to some extent across SC and vicinity Tuesday afternoon.
Regardless, confidence has increased that isolated to scattered
thunderstorms capable of producing occasionally strong to damaging
winds should occur, and a Marginal Risk has been introduced to
account for this potential.

..Gleason.. 08/12/2024

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