865
ACUS01 KWNS 191959
SWODY1
SPC AC 191957

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Wed Aug 19 2026

Valid 192000Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE LOWER MISSOURI VALLEY...THE MID MISSISSIPPI VALLEY...AND
SOUTHERN ARIZONA...

...SUMMARY...
Thunderstorms capable of severe wind gusts and hail will be possible
this afternoon across the lower Missouri Valley, the mid Mississippi
Valley, and southern Arizona.

...20z Update...
A compact, but severe, MCS has begun tracking eastward along a
residual/diffuse frontal zone into southeast NE. Based on the recent
18 UTC OAX RAOB, the MCS is beginning to orient more orthogonal to
the deep-layer bulk shear vector, which should continue to promote
storm organization and intensity. The potential for severe winds,
including winds near 75 mph, should continue through late afternoon
and early evening hours before moving into more stable air mass
across north-central MO. See MCD #2041 for additional short-term
details.

...Mid-Mississippi Valley/lower Ohio Valley...
Recent GOES visible imagery and surface observations show
temperatures rebounding into the low to mid 80s as skies clear ahead
of an approaching mid-level wave. This destabilization appears to be
on track with recent guidance, which suggests that initially
discrete/semi-discrete storm development should begin by around
22-00 UTC across south-central MO on the western fringe of the
residual cold pool. Forecast soundings from this region depict
elongated hodographs conducive for large hail, including the
potential for hail up to 2 inches in diameter (based on sounding
analogs and hodograph structure). Given a favorable kinematic
environment, adequate buoyancy, and a signal in recent high-res
ensemble guidance for strong convection, a CIG 1 hail contour has
been introduced to portions of southern Missouri.

Elsewhere, only minor modifications were made based on recent
convective trends. See the discussion below and MCD #2040 for
additional details.

..Moore.. 08/19/2026

.PREV DISCUSSION... /ISSUED 1134 AM CDT Wed Aug 19 2026/

...Mid MO Valley...
Radar/visible satellite mosaic imagery depicts a small cluster of
severe thunderstorms immediately ahead of a migratory shortwave
trough moving southeast over the mid MO Valley.  Some heating
downstream of this activity will result in temperatures warming and
the airmass gradually destabilizing amid filtered sunshine.  Gradual
upscale growth is underway and should continue into the early
afternoon.  Large hail and severe gusts 60-70 mph will be the
primary severe hazards as this cluster moves into adjacent portions
of NE/MO/IA later this afternoon.

...Ozarks into the Mid MS Valley...
Residual showers/thunderstorms from an overnight MCS over the
southeast MO into western KY vicinity will slowly dissipate this
afternoon with greater heating ensuing in the wake of these storms.
Models continue to show moderate destabilization by late this
afternoon ahead of the MO Valley upper vort.  Weak low-level
convergence along an upstream cold front will support thunderstorm
development within this destabilized airmass this evening.
Strengthening mid-level flow will result in moderate to strong
deep-layer vertical shear supportive of supercells.  Models vary
regarding the propensity for cellular mode to be maintained beyond
the initial storm development phase, casting doubt on supercell
longevity and tornado potential.  Nonetheless, some strengthening of
850-mb flow during the evening may enable some mesocyclone potential
to persist, and an accompanying isolated risk for a tornado or two.
Otherwise, storms will tend to cluster with eastward extent, with
the threat for damaging gusts persisting within these bowing line
segments.

...Ohio Valley...
A somewhat secondary area of late afternoon/early evening
thunderstorm development is anticipated from central IL into central
IN and central OH.  Moderate buoyancy and strong westerly flow aloft
supports the potential for isolated supercells capable of large hail
and isolated damaging gusts.

...Central/Southern High Plains...
A seasonably moist airmass will undergo strong heating/mixing and
result in moderate buoyancy by mid-late afternoon. Thunderstorm
development is expected across the higher terrain before then
progressing eastward into the lower elevations.  Moderate
northwesterly flow aloft will support organized storms
structures, and large hail is possible along the Foothills.
Steep lapse rates and large temperature-dewpoint depressions will
lead to outflow-dominant storms capable of severe gusts with the
more intense cores/outflow.

...AZ...
The presence of monsoon moisture will support moderate buoyancy
across the lower elevations of south-central AZ during the late
afternoon.  Scattered storms are expected to eventually develop
towards the early evening.  Trends in model guidance showing a
cluster potentially evolving within an adequately moist/inverted-V
environment lend confidence in introducing a level 1 intensity
highlight for peak gusts in the 70-80 mph range.

...Southeast into northern FL...
A very moist airmass analyzed late this morning (mid to upper 70s F
surface dewpoints) will remain in place along the Gulf Coast. Strong
heating is anticipated, with high temperatures in the upper 90s
across much of the region.  As surface temperatures warm, moderate
instability will develop, with scattered thunderstorms expected amid
modest low-level convergence from MS into western/southern AL and
across the FL Panhandle into northern FL.  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.

$$