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
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