Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1132 AM CDT Thu Aug 13 2026
Valid 131630Z - 141200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MIDWEST...
...SUMMARY...
Isolated to scattered severe thunderstorms are possible today from
parts of the southern/central High Plains to the Midwest. Severe
wind gusts should be the main threat, but some hail may also occur.
...Midwest including parts of eastern Iowa and Illinois/Indiana...
Supported by an MCV, a long-lived MCS continues to move
east-southeastward into west-central/northwest Illinois late this
morning. Greater stability initially precedes the MCS across
northern Illinois, but the remnant cluster and additional
redevelopment will likely tend to favor a more southeastward
progression in closer proximity to the front/instability gradient
that extends across Illinois/Indiana, with additional/renewed
development and intensification possible into the afternoon and
evening. Damaging wind gusts will be the primary severe hazard,
although a brief tornado and marginally severe hail are also
possible into this evening. While not certain, additional severe
redevelopment may also occur tonight farther west/northeastward
across areas potentially including eastern Iowa and northern/central
Illinois as a low-level jet nocturnally increases.
...Southern/Central High Plains...
High-based thunderstorms are expected to initially develop over the
higher terrain of the central Rockies/Front Range this afternoon,
with post-frontal low-level upslope flow persisting across the
central High Plains. Storm motions into slightly richer moisture
will favor some aggregation of outflow within a hot boundary layer
featuring steep lapse rates. Isolated to widely scattered severe
wind gusts 60-75 mph are possible, along with occasional hail with a
few of the stronger cores.
...Great Basin...
Modestly enhanced southwesterly mid-level flow will persist today
across the Great Basin downstream of a weak mid-level trough over
California. Weak to locally moderate instability is forecast via
diurnal heating. Scattered to numerous thunderstorms are expected
and some of the stronger evaporatively cooled downdrafts will be
capable of 60-75 mph gusts.
...Northeast...
Seasonably cool mid-level temperatures are forecast today across
parts of the Northeast, with a mid-level trough expected to move
east-southeastward from Quebec into New England. While instability
is forecast to remain fairly limited, strong west-northwesterly flow
aloft may support a risk for isolated damaging winds (50-65 mph)
with thunderstorms that develop and spread southeastward through the
afternoon. Isolated hail may also occur with the stronger cells.
..Guyer/Chalmers.. 08/13/2026
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