ACUS02 KWNS 130601
SWODY2
SPC AC 130600

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Tue Aug 13 2024

Valid 141200Z - 151200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTHEAST KANSAS...EASTERN NEBRASKA...SOUTHWEST IOWA...AND NORTHWEST
MISSOURI...

...SUMMARY...
Isolated to scattered severe thunderstorms should occur Wednesday
across parts of the northern/central Plains into the mid Missouri
Valley, with greater potential for large hail and damaging winds
across parts of northeast Kansas, eastern Nebraska, southwest Iowa,
and northwest Missouri.

...Northern/Central Plains into the Mid Missouri Valley...
Thunderstorms that should be ongoing at the start of the period
Wednesday morning across parts of the mid MO Valley should gradually
decrease in coverage and intensity through the early afternoon as a
southwesterly low-level jet and related warm advection slowly
weakens. Upper ridging is forecast to remain prominent through the
period across the lower MS Valley/Southeast into the Midwest and
Great Lakes. Upstream, weak upper troughing is expected to become
established over the northern/central Plains, with multiple
low-amplitude mid-level perturbations forecast to move eastward
across these regions. At the surface, a broad warm sector should be
in place along/ahead of a weak front/lee trough. Most guidance
suggests that multiple weak surface lows should generally
consolidate over parts of central/eastern NE/KS by early Wednesday
evening.

Greater low-level moisture, characterized by upper 60s to low 70s
surface dewpoints, should be in place across parts of the central
Plains into the mid MO Valley. This moisture is forecast to advect
northward in tandem with a sharpening warm front through the day,
although considerable uncertainty still exists with how far north
into IA the warm sector will be able to develop. Robust
thunderstorms should develop by late Wednesday afternoon across
parts of eastern NE and northeast KS in the vicinity of a weak
surface low and triple point. Moderate to strong instability will
likely be in place due to ample daytime heating of the rather moist
airmass, along with somewhat steepened mid-level lapse rates.

Even though mid/upper-level flow is forecast to be only modestly
enhanced, veering and gradual strengthening of the wind field with
height should support enough deep-layer shear for a mix of
multicells and supercells initially. Both large hail and
severe/damaging winds appear possible. A low-level jet is also
forecast to strengthen Wednesday evening across eastern NE/KS into
IA. Any supercell that can remain at surface based could also pose
some threat for a tornado across this area given strengthening
low-level shear Wednesday evening. Otherwise, a bowing cluster may
eventually develop and pose more of a damaging wind threat as it
spreads east-northeastward across the mid MO Valley Wednesday
evening and overnight.

Other strong to severe thunderstorms appear possible across a
broader portion of the northern/central Plains, although instability
is forecast to generally become weaker with northward and westward
extent. Still, weak to locally moderate instability and sufficient
deep-layer shear for modestly organized updrafts should exist across
much of the warm sector Wednesday afternoon and evening. An isolated
threat for both hail and strong to severe wind gusts remains
apparent, and the Marginal Risk has been expanded in multiple areas
to account for latest guidance trends in where strong to severe
convection may develop.

..Gleason.. 08/13/2024

$$
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