Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1257 AM CDT Wed Aug 19 2026
Valid 191200Z - 201200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MID MISSISSIPPI VALLEY...
...SUMMARY...
Thunderstorms with severe wind gusts and hail will be possible this
afternoon across the mid Mississippi Valley. Isolated severe gusts
and hail will also be possible from the lower to mid Missouri Valley
westward into the Great Plains. A few severe gusts could also occur
in southern Arizona and in the Southeast.
...Mid Mississippi Valley...
At mid-levels, a shortwave trough and an associated speed max will
move southeastward into the mid Mississippi Valley today. At the
surface, an outflow boundary associated with morning convection will
move southward into southern Missouri by midday. To the north of the
boundary, surface dewpoints will be in the 70s F. Moderate
instability is expected to develop in areas that are not impacted by
morning outflow. As low-level convergence becomes focused near the
boundary during the late afternoon and early evening, isolated to
scattered convective initiation is expected. From this convection,
thunderstorms will likely develop and move eastward across the mid
Mississippi. One or two organized line segments will be possible
during the evening.
Early evening RAP forecast soundings in south-central Missouri,
where the strongest instability is expected, have 0-6 km shear
around 40 knots with precipitable water near 2 inches. MLCAPE is
expected to peak in the 2500 to 3000 J/kg range with 0-3 km lapse
rates around 7.5 C/km. This environment will support a severe threat
with supercells and multicell line segments. Severe wind gusts and
hail will be the primary hazards. The severe threat could persist
into the mid to late evening, with storms that are maintained by a
low-level jet that is forecast to strengthen in southeast Missouri.
...Great Plains...
Mid-level northwesterly flow will be in place across the Great
Plains today. At the surface, dewpoints in the 60s and 70s F will
contribute to moderate destabilization over much of the region.
During the afternoon, isolated storm development will be possible
within the unstable airmass from the lower to mid Missouri Valley
southwestward into the central Plains. A few severe gusts and hail
will be possible but the storms will remain isolated due to limited
large-scale ascent. The greater convective coverage is expected
further south in the higher terrain of eastern Colorado and
northeast New Mexico. Thunderstorms will likely form due to
topographic forcing during the mid to late afternoon and move
east-southeastward into the lower elevations. Ahead of these storms,
RAP forecast soundings at 00Z in the northern Texas Panhandle and
southwest Kansas have 0-6 km shear around 40 knots with 0-3 km lapse
rates near 8 C/km, and surface-temperature dewpoint spreads
exceeding 30 degrees. This environment will support an isolated
potential for severe gusts.
...Southern Arizona...
Low-level moisture will be in place today across southern Arizona,
where surface dewpoints will be mostly in the 50s F. As surface
temperature warm, isolated to scattered convective initiation will
occur in the higher terrain of southeastern Arizona. These storms
will move west-southwestward toward an axis of instability. Steep
low to mid-level lapse rates and large temperature-dewpoint spreads
will support and isolated potential for severe gusts late this
afternoon into early evening.
...Southeast...
A very moist airmass will be in place today across the Southeast,
where surface dewpoints will be in the 70s F. As surface
temperatures warm, moderate instability will develop over much of
the region. Scattered thunderstorms are expected to develop and move
southward across parts of Mississippi and western Alabama. The deep
low-level moisture combined with steep low-level lapse rates will
support an isolated wind-damage threat during the mid to late
afternoon.
..Broyles/Thornton.. 08/19/2026
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