ACUS01 KWNS 112001
SWODY1
SPC AC 112000

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Tue Aug 11 2026

Valid 112000Z - 121200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
INTO EARLY TONIGHT ACROSS PARTS OF THE MIDDLE OHIO VALLEY...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
NORTHERN PLAINS...AND FROM EASTERN ILLINOIS TO VIRGINIA AND NORTH
CAROLINA...

...SUMMARY...
Severe thunderstorms with damaging wind gusts will continue today
across parts of the Ohio Valley and central Appalachians. Large hail
and severe wind gusts are also forecast over parts of the northern
Plains.

...20Z Update...
The primary change with this update was trimming higher severe
probabilities in the wake of earlier convection that moved through
parts of eastern IL, northern IN, and northwestern OH. With that
said, a risk of severe wind gusts and hail will persist through some
of this corridor -- within a relatively narrow zone of
moderate-strong surface-based buoyancy along the southern edge of outflow-modified air. Refer to Severe Thunderstorm Watch 565 and MCD
1930 for more information.

Farther east, a well-established MCS is tracking southeastward
across southern OH toward northern KY. Over the next few hours,
these storms will continue to pose the greatest risk for a swath of
damaging wind gusts (some upwards of 75 mph) as they track
southeastward along a gradient of strong surface-based buoyancy amid
40 kt of deep-layer shear oriented perpendicular to the
well-established gust front. Additionally, a modest enhancement to
the low-level shear along the buoyancy gradient/baroclinic zone will
continue to support brief mesovortex tornadoes in the near-term. See
MCD 1931 for more information.

Elsewhere, the previous forecast remains on track and only minor
changes were made to the outlook.

..Weinman.. 08/11/2026

.PREV DISCUSSION... /ISSUED 1111 AM CDT Tue Aug 11 2026/

...IL/IN/OH...
A fast moving and intense bowing MCS is affecting the Chicago metro
area this morning with significant severe wind gusts. This activity
will race east-southeastward across northern IN and eventually
western OH. Increasingly widespread thunderstorms and associated
outflow ahead of this complex lends uncertainty to the evolution of
the bow, and the corridor of greatest damaging wind potential.
Refer to MDs #1921 and #1922 for further details.

...OH/WV/KY/VA...
Another linear MCS is affecting southeast OH, and will spread across
WV and into VA later today. The air mass ahead of this complex is
not as unstable, and considerable uncertainty exists regarding this
system's longevity. Nevertheless, sufficient flow aloft and
mesoscale organization will maintain a risk of damaging wind gusts.
Refer to MD #1923 for further details.

...ND/SD/NE...
Moderately strong westerly flow aloft is present today across the
Dakotas, with a moist and unstable air mass in place over the Black
Hills region. This will likely lead to widely scattered
thunderstorm development by early evening. Supercells capable of
large hail and damaging winds are expected. It is unclear how far
southeast these storms will maintain intensity, but model guidance
suggests at least into central SD before weakening overnight.

$$

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