Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0719 AM CDT Fri Sep 18 2026
Valid 181300Z - 191200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE CAROLINAS INTO NORTHERN GEORGIA...PARTS OF THE CENTRAL HIGH
PLAINS...IOWA...AND IN THE INTERMOUNTAIN WEST...
...SUMMARY...
An isolated severe risk is forecast later today into the evening for
the Carolinas into northern Georgia, Iowa, parts of the central High
Plains, and parts of the Intermountain West.
...Carolinas/Northern Georgia...
A cluster of weak thunderstorms ongoing this morning over KY-WV near
a surface front will continue southward via northerly steering flow
on the eastern periphery of a mid-level anticyclone centered over
the Ark-La-Tex. A weak upper impulse associated with this activity
may influence a rejuvenation of storms near the leading edge of
convective outflow across the VA/NC border vicinity. As the
boundary layer heats to the south of the front, other scattered
storms are expected to develop over the Piedmont into northern GA
this afternoon. Isolated strong to locally severe gusts (50 to 60
mph) capable of wind damage may occur with the stronger thunderstorm
cores.
...Iowa...
Surface mesoanalysis this morning places a front draped from the
lower OH Valley westward into the mid MO Valley with an accompanying
weak surface low over western NE. Seasonably moist low levels
(lower 70s F surface dewpoints) are south of the boundary across the
lower OH Valley west-northwestward into eastern NE. The boundary is
forecast to gradually advance north-northeastward through IA during
the period driven by a persistent belt of 30+ kt flow via a
southwesterly 850 mb jet, thereby maintaining a corridor of
low-level warm-air advection across the area. Model guidance
signals higher probabilities for thunderstorm activity over IA into
far southern MN where low-level forcing and heating will locally
erode convective inhibition. Although marginally severe gusts will
probably be the primary hazard, enlarged hodographs near the warm
front may yield a localized risk for a couple of weak, short-lived
supercells [longer-lived supercell structures limited by weak
(20-kt) flow above 500 mb]. Upscale growth into a larger convective
system may occur during the late evening into the overnight, but
will likely become increasingly displaced from appreciable buoyancy
as it moves towards the southwest Great Lakes.
...Intermountain West...
A mid-level trough will move eastward across the Intermountain West
today. Southwest flow aloft will be in place ahead of the trough
over much of the region. At the surface, dewpoints in the 50s F are
expected from northern Utah into valleys of western Wyoming, where
the RAP is forecasting MLCAPE to peak in the 1000 to 1200 J/kg
range. In addition to the instability, forecast soundings show
moderate deep-layer shear in response to the approaching mid-level
trough. As low to mid-level lapse rates become steep in the late
afternoon and early evening, isolated severe gusts and hail will be
possible.
...Central High Plains...
Radar mosaic and water-vapor imagery this morning show a
convectively enhanced, mid-level vorticity maximum moving
north-northeast over central NM. This disturbance is forecast to
possibly influence storm development later today into this evening
in a primarily post-frontal regime over the central High Plains.
Ample heating of the boundary layer over eastern CO into adjacent
portions of southwest NE/northwest KS will precondition an
environment as initially isolated to widely scattered storms
potentially grow upscale into a small, eastward-moving cluster this
evening. Isolated severe gusts may accompany the stronger outflow
surges with this activity.
..Smith/Mead.. 09/18/2026
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