Mesoscale Discussion 2010
NWS Storm Prediction Center Norman OK
1031 AM CDT Mon Aug 17 2026

Areas affected...parts of west central into central Arkansas

Concerning...Severe potential...Watch unlikely 

Valid 171531Z - 171730Z

Probability of Watch Issuance...20 percent

SUMMARY...A small cluster of storms may continue to pose a risk for
strong surface gusts approaching severe limits, with perhaps a
period of some increase in peak gusts, before probably weakening by
early afternoon.  It is not clear that this requires a severe
weather watch, but trends are being monitored.

DISCUSSION...The most prominent convection has become confined to a
shrinking, but still fairly vigorous core approaching the Fort Smith
vicinity.  There have been fluctuations in intensity, but a recent
increase may be associated with increasing updraft inflow of moist
air characterized by sizable CAPE in excess of 2000 J/kg.  Based on
Rapid Refresh output this is focused in a narrow corridor along and
north of a southward advancing baroclinic zone in the 925-850 mb
layer, which may continue to slowly advance southward across the
I-40 corridor of western through central Arkansas into midday.

Radar data indicates the continuing presence of strong inflow (on
the order of 50-70+ kt) into the rear of the convective system
near/above 1 km AGL.  However, aside from a severe gust to 51 kt at
Muskogee around 1421Z, peak surface gusts have mostly been near or
below 45 kt based on mesonet observations. 

Based on latest objective instability analysis, it is possible that
activity could be maintained into the 17-19Z time frame.  As it
approaches the Little Rock vicinity, a period of increasing
potential for severe gusts might not be out of the question, before 
possibly acquiring updraft inflow of drier/less unstable air and
weakening, as has generally been suggested by convection-allowing
guidance.

..Kerr/Guyer.. 08/17/2026

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...LZK...TSA...

LAT...LON   35959447 35619282 35029276 34829337 35309465 35549453
            35959447 

MOST PROBABLE PEAK WIND GUST...55-70 MPH

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0754 AM CDT Mon Aug 17 2026

Valid 171300Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN AND CENTRAL PLAINS...AND THE SOUTHERN APPALACHIANS INTO
THE NORTH CAROLINA PIEDMONT...

...SUMMARY...
Thunderstorms with severe wind gusts and hail will be possible this
afternoon and evening across parts of the central and northern
Plains. Damaging gusts will also be possible in parts of the
southern Appalachians into the North Carolina Piedmont, Oklahoma and
Arkansas.

...Northern/Central Plains...
Modest height falls are expected across the northern Plains as
troughing over central Canada deepens. As it does, an associated
surface low will shift eastward and an attendant cold front will
push southward/southeastward across eastern MT, ND, and northwest
MN. The airmass preceding this front will be moist and strongly
unstable, with dewpoints likely in the upper 60s and MLCAPE over
2500 J/kg. Several different areas of initial development appear
possible, including along the front from eastern ND into
northwestern MN, in the vicinity of the pre-frontal trough over the
NE Panhandle vicinity, and south of the front across eastern MT. 

Development across eastern ND/northwestern MN and the NE Panhandle
should progress southeastward into the corridor of greater buoyancy.
Even so, weak ascent and relatively warm mid-levels could limit both
overall storm coverage and updraft longevity. That being said,
vertical shear will be strong enough to support updraft organization
and supercell structures with any deep updrafts. Steep low-level
lapse rates and high cloud bases suggest strong gusts are the
primary severe risk, but some isolated large hail is also possible.
Widely scattered nature of the storms casts doubt regarding upscale
growth into a coherent MCS, but several separate bowing clusters
appear probable.

Thunderstorm coverage is expected to remain isolated from central
into eastern MT as well, with modest ascent attendant to a shortwave
trough progressing through the northern periphery of the western
CONUS ridging acting as the primary impetus for initiation.
Predominantly outflow-dominant storm structures are anticipated,
with strong gusts as the primary severe risk through the evening.
Convective evolution is uncertain, but these storms could continue
eastward through SD and NE overnight, reintensifying as they
interact with the stronger buoyancy expected to be in place. In
addition to strong gusts, large hail would be possible with these
storms if reintensification occurs.  

...Central/Southern Appalachians into the Piedmont...
Early-morning satellite and regional radar imagery show a decaying
MCS progressing across central KY, well ahead of weak cold front
that extends from far northwest OH southwestward through far
southeast MO and northern AR. This MCS is forecast to continue
eastward throughout the day, moving through the central Appalachians
and eventually central VA. The airmass over this region is very
moist, with recent surface analysis sampling upper 60s dewpoints
over the higher terrain and low to mid 70s farther east from central
VA into the Carolina Piedmont. 

General expectation is for renewed thunderstorm development along
the southern flank of the MCS, likely from far southeast KY into
Middle TN. Some reintensification is also possible farther north
over WV and downstream in northern/central VA, but buoyancy will be
lower than farther south, suggesting predominantly muted/transient
updrafts. Currently, the highest storm coverage appears most likely
across far western WV, eastern TN, and western NC. Vertical shear
will be weak, but moderate/strong buoyancy and steep low-level lapse
rates will still support the potential for damaging gusts. These
strong outflows could promote the development of several
forward-propagating line segments, where updrafts/downdrafts along
the outflows could result in additional damaging gusts.

...Oklahoma/Arkansas...
An MCS continues to progress eastward into northeast OK this
morning, with a well-defined MCV noted in radar imagery back across
far northwest OK. An associated outflow boundary currently arcs from
the leading edge of the MCS in Osage County back southwestward
through southwest OK. This MCS is forecast to weaken as it
progresses eastward this morning, with weakening outflow also moving
southeastward. A composite outflow/cold front will likely extend
from southern OK into central AR this afternoon. Low-level
convergence near this boundary will likely result in widely
scattered thunderstorms by the late afternoon. Vertical shear will
be weak, limiting storm organization. However, moderate instability,
high cloud bases, and steep low-level lapse rates will still support
the potential for isolated severe downbursts.

..Mosier/Dean.. 08/17/2026

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1152 AM CDT Mon Aug 17 2026

Valid 171630Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTH-CENTRAL PLAINS/UPPER MIDWEST AND SOUTHERN APPALACHIANS...

...SUMMARY...
Thunderstorms with severe wind gusts and large hail are expected
this afternoon and evening across parts of the central and northern
Plains. Damaging gusts will also be possible in parts of the
southern Appalachians to the North Carolina Piedmont, and possibly
across portions of the Mid-South and southern Plains.

...Northern/Central Plains...
Weak height falls are expected regionally with a seasonally
prominent strengthening of northwesterly flow aloft. A surface low
will shift eastward and an attendant cold front will push
southward/southeastward across eastern Montana, North Dakota and
toward west/northwest Minnesota. The airmass preceding this front
will be moist and strongly unstable, with dewpoints in the upper 60s
and MLCAPE over 2500 J/kg. Multiple areas of initial development are
expected, including along the front from eastern Dakotas into
western Minnesota, and in the vicinity of the pre-frontal trough
and/or front over the NE Panhandle vicinity, southern South Dakota,
and southeast Montana/far eastern Wyoming.

Mid/Late-afternoon storm development in each of these areas will
progress into zones of greater buoyancy by evening. Some initial
supercells capable of large hail are expected, especially given the
strength of the deep-layer wind profiles, while steep low-level
lapse rates and high cloud bases will support strong wind gust
potential, especially with the possibility that storms may
cluster/organize this evening across Nebraska/southern South Dakota,
and possibly across Siouxland and western Minnesota. 

...Central/Southern Appalachians into the Piedmont...
Within a very moist airmass, renewed thunderstorm development is
expected along the southern flank of a remnant thunderstorm cluster
and in vicinity of the higher terrain/mountains this afternoon.
Vertical shear will not be overly strong, but moderate/strong
buoyancy and steep low-level lapse rates will still support the
potential for damaging wind gusts. These strong outflows could
promote the development of several
forward-propagating/southeast-moving line segments with a persistent
potential for wind damage, at least through early evening.

...Oklahoma/Arkansas to Mid-South...
Aided by an MCV, a small cluster of storms with a morning history of
occasional severe-caliber winds continues at midday across northwest
Arkansas. For additional short-term details, see Mesoscale
Discussion 2010. While not certain or perhaps likely, a general
eastward-persistence of this cluster could occur. Additional
isolated storm development may occur regionally later this afternoon
along the remnant outflow and/or front, with steep low-level lapse
rates and ample buoyancy supportive of damaging downburst potential
through around sunset.

..Guyer/Chalmers.. 08/17/2026

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1227 PM CDT Mon Aug 17 2026

Valid 181200Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN
KANSAS...CENTRAL TO SOUTHEAST NEBRASKA...SOUTHWEST IOWA...AND
NORTHWEST MISSOURI...

...SUMMARY...
Severe thunderstorms capable of large hail and damaging wind gusts
are expected Tuesday afternoon/evening across parts of the central
Plains and toward the Lower Missouri/Mid-Mississippi Valley.

...Central Plains to Mid/Upper MS Valley...
The presence, or lack, of morning convection will have a significant
impact on the evolution of storms on Tuesday. From the 12Z HREF
cycle, a majority of the CAM members have a cluster of storms across
eastern Nebraska at 12Z. Given the environment in the region, this
cluster would at least have some marginal hail/wind threat. Most
guidance has this cluster dissipating as the low-level jet weakens.
Given a more stable environment east of this activity this seems
like the most likely scenario. If this cluster can persist until
late morning when the downstream airmass destabilizes to the south,
it could turn right and persist across Missouri, but evidence for
this is quite low. 

Whatever boundaries any morning storms leave behind will likely be
the focus for diurnal storm development. Overall forcing is quite
low which may lead to isolated to widely scattered storm
development. However, 45 to 55 knots of mid-level flow from the
KS/NE border northward will provide ample shear for storm
organization, including supercells. In fact, some 2-3 inch hail
seems likely with any longer-lived supercells which may develop
within this most favorable environment. 

Additional thunderstorms are expected during the overnight period
from northern Kansas to central Missouri, within a region of
isentropic ascent. The location of the 850mb front and the best
forcing still has some uncertainty, but thunderstorm activity will
be most likely from northeast Kansas to northwest Missouri. As
storms congeal and a cold pool forms, a wind-producing MCS may
develop out of this cluster. This is most prominently shown by the
WRF-NSSL and the WRF-ARW. Therefore, a CIG1 wind intensity has been
added across this region for this conditional 75+ mph wind threat
associated with a MCS in the forecast environment.

..Bentley.. 08/17/2026