655
ACUS01 KWNS 151942
SWODY1
SPC AC 151941

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0241 PM CDT Sat Aug 15 2026

Valid 152000Z - 161200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF THE
OHIO VALLEY AND PARTS OF THE CENTRAL HIGH PLAINS...

...SUMMARY...
Thunderstorms with severe wind gusts and isolated large hail remain
possible from late afternoon into the evening across the central
High Plains. Severe wind gusts may also still occur this afternoon
through early evening across parts of the Ohio Valley and Southeast.

...20Z Update...
The previous forecast (see below) remains generally on track, with
only minor changes made to the 20Z Day 1 Convective Outlook Update
to reflect the latest observations and latest guidance consensus.
There were considerations to add a Category 1/Marginal Risk for
severe wind/hail over portions of the Pacific Northwest into the
northern Rockies given appreciable cool temperatures aloft
overspreading a heated boundary layer. Nonetheless, vertical wind
shear should remain quite weak. Therefore, while a 50+ kt gust or
instance of 1+ inch hail may occur with any of the stronger storms,
the severe threat should be very sparse, precluding severe
probabilities this outlook.

..Squitieri.. 08/15/2026

.PREV DISCUSSION... /ISSUED 1135 AM CDT Sat Aug 15 2026/

...Front Range/Central High Plains...
Modestly strong southwesterly flow aloft coupled with strong
daytime heating, low-level upslope flow, and orographic lift will
support another day of thunderstorms regionally. These thunderstorms
should gradually move off the higher terrain into the central High
Plains later this afternoon, where a moderately
buoyant airmass will be in place. Around 30-35 kt of effective
bulk shear is expected over the region, which will support a mixed
mode with supercells and multicell line segments. Isolated large
hail is possible with any supercells, while severe wind gusts will
be possible with both supercells and line segments. The severe
threat should persist into the evening as this complex of storms
moves eastward through the central High Plains including
west/southwest Kansas.

...Midwest/Middle Ohio Valley...
Thunderstorms have generally weakened since the overnight, although
scattered showers/some thunderstorms and plentiful cloud cover
continue in areas progressively north of the Ohio River. An MCV is
readily apparent in observational data as it continues to move into
northwest Indiana, with an enhanced belt (40+ kt) of westerly winds
associated with the MCV per regional WSR-88D VWP data.

As clouds thin/abate, a gradual increase in renewed thunderstorm
coverage and intensity is expected later this afternoon. Mid-level
lapse rates will be poor, but dewpoints in the 70s F will support
moderate buoyancy, particularly in areas where cloud cover does not
overly inhibit diurnal heating, which will tend to generally be
southward toward the Ohio River. Strong updrafts and high
precipitable water will support the potential for wet microbursts
capable of producing damaging gusts, and some enhancement to the
low-level winds could also yield a brief tornado.

...Central Appalachians/Carolinas/Georgia...
A very moist airmass, characterized by dewpoints in the low to mid
70s, is in place regionally. Strong heating will destabilize the
airmass by the early afternoon, resulting in a large reservoir of
moderate buoyancy. Thunderstorm development is anticipated within
this destabilized airmass across the higher terrain of the central
Appalachians as well as any area of low-level convergence across the
remainder of the region. Vertical shear will be weak, and limited
storm organization is anticipated. Even so, the moderate buoyancy
could still support updrafts/downdrafts strong enough to produce
occasional damaging gusts.

...Central Plains/Mid Missouri Valley to Mid Mississippi Valley...
Elevated thunderstorms are expected again tonight, initiated by both
an approaching cold front and warm-air advection. Ample low-level
moisture and moderate buoyancy will be in place, but vertical shear
will be marginal. Isolated strong to severe storms are expected, but
a predominantly elevated and clustered storm mode should limit the
overall severe potential.

$$