ACUS01 KWNS 311301
SWODY1
SPC AC 311259

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 AM CDT Wed Jul 31 2024

Valid 311300Z - 011200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
MIDDLE MISSOURI VALLEY AND UPPER MIDWEST...

...SUMMARY...
Another active severe-weather day is expected from the
northern/central Plains and Upper Midwest to the southern
Appalachians. This includes potential for large hail across parts of
the northern/central Plains, aside from a more prevalent risk of
damaging winds, some of which could be significantly strong.

...Great Plains/Mid-Missouri and Mid-Mississippi Valleys...
A relatively prominent summertime mid-level trough is readily
apparent across the northern High Plains early this morning, and
will reach the Upper Midwest tonight. Ahead of this trough,
scattered occasionally strong/locally severe convection has occurred
overnight across northern South Dakota into southern/eastern North
Dakota. This convection should further increase into midday/early
afternoon, with a more appreciable severe risk evolving across
north-central/eastern South Dakota, and eventually into southwest
Minnesota by mid/late afternoon. Some initial supercells capable of
very large hail will be possible, but storm mergers within a very
unstable environment by mid/late afternoon should lead to MCS
development and heightened wind potential.

Additional potentially intense storm development is expected
southwestward near the cold front into Nebraska and Kansas, with
large hail and severe-wind gusts expected. One or more organized
clusters should regionally evolve by early/mid-evening across the
Siouxland and far eastern Nebraska into much of Iowa. Potentially
significant wind gusts in excess of 75 mph are plausible given the
steep lapse rate environment and reservoir of strong to extreme
buoyancy. Severe-MCS persistence seems viable tonight across much of
Iowa/southern Minnesota, possibly northern Missouri, and Illinois.

...Central Plains/southern High Plains...
Isolated to scattered thunderstorms are expected to develop along
and ahead of the front. Deep-layer shear will be strong enough for
an isolated severe threat. Large to very large hail will be possible
with supercells in parts of central Kansas. However, the environment
will be less favorable further southwest with more of an
isolated/marginal overall severe threat expected across southwest
Kansas into northwest Oklahoma and the Texas Panhandle.

...Lower Ohio Valley/Cumberland Plateau/Southern Appalachians...
Similar to yesterday, a seasonally strong belt of northwesterly flow
aloft will persist today from the lower Ohio Valley to the southern
Appalachians and coastal Southeast. Much of this will reside atop a
moist and very unstable air mass, especially across parts of the
lower Ohio Valley to Cumberland Plateau, where upwards of 3000-4000
J/kg MLCAPE may develop by peak heating outside of any MCS-related
impacts. This general scenario will likely support several organized
severe-producing storms clusters/MCSs through the evening across
these regions. Somewhat higher severe probabilities (Enhanced
category) may be warranted in subsequent outlooks for parts of these
region.

For one, an MCS ongoing across central Illinois this morning may
potentially persist southeastward within this increasingly unstable
environment, possibly impacting areas such as southern Indiana,
southern Ohio and parts of Kentucky/Tennessee with a heightened wind
damage potential. Aided by differential heating, scattered storms
should also increase across the southern Appalachians vicinity this
afternoon, with some organization into clusters possible given the
aforementioned relative strength of winds aloft, with wind damage
possible.

...Southern Arizona...
An upper low near Baja and ongoing early day storms across parts of
northwest Mexico may influence thunderstorm development this
afternoon within a moist air mass particularly across southeast
Arizona. Some of the storms could produce severe-caliber wind gusts
and blowing dust this afternoon into early evening.

..Guyer/Grams.. 07/31/2024

$$
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