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
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