SPC Sep 19, 2026 0100 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 0100Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0745 PM CDT Fri Sep 18 2026

Valid 190100Z - 191200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MID MISSOURI VALLEY...CENTRAL HIGH PLAINS AND INTERMOUNTAIN
WEST...

...SUMMARY...
Thunderstorms with isolated severe wind gusts will be possible this
evening across parts of the mid Missouri Valley and Central High
Plains. A few severe wind gusts and hail may occur in parts of the
Intermountain West.

...Mid Missouri Valley...
An upper-level ridge is currently present in the central U.S, with a
30 to 40 knot low-level jet located near the ridge in the mid
Missouri Valley. Isolated thunderstorms have developed early this
evening in eastern Nebraska, near the axis of the low-level jet.
Surface dewpoints in eastern Nebraska are in the lower to mid 70s F,
with the RAP showing MLCAPE in the 1000 to 2000 J/kg range. While
the 00Z Omaha sounding has 0-6 km shear of 20 to 25 knots,
deep-layer shear is likely a bit stronger southward in the vicinity
of the low-level jet. This could be enough for an isolated
wind-damage threat. The threat may develop northeastward into
western and central Iowa this evening as low-level flow and
convective coverage both increase.

...Central Plains...
An anti-cyclonic flow pattern is present over much of the
north-central U.S. The eastern extension of a mid-level shortwave
trough, evident on water vapor imagery, is located over east-central
Colorado. Scattered thunderstorms are ongoing just ahead of the
trough from northeast Colorado into southwest Nebraska, where the
RAP has MLCAPE in the 1000 to 2000 J/kg range. The WSR-88D VWPs at
Goodland and Cheyenne have 0-6 km shear in the 30 to 40 knot range,
suggesting that an isolated severe threat will be possible early
this evening. Severe wind gusts will be the primary threat.

...Intermountain West...
On water vapor imagery, southwesterly mid-level flow is present from
the central Rockies into the central High Plains. A mid-level
shortwave trough appears to be located from near the Unita Mountains
in northeast Utah eastward into the central Rockies of Colorado.
Large-scale ascent associated with the trough is supporting
scattered thunderstorm development. The RAP shows the strongest
instability across northeast Utah and northwest Colorado, where
moderate deep-layer shear and modestly steep lapse rates are evident
on RAP analysis. This could be enough for an isolated potential for
severe wind gusts and hail over the next few hours.

..Broyles.. 09/19/2026


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SPC Sep 18, 2026 1630 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1630Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Fri Sep 18 2026

Valid 181630Z - 191200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
CAROLINA PIEDMONT INTO NORTHERN GEORGIA...NORTHERN IOWA...PARTS OF
THE CENTRAL HIGH PLAINS...AND PARTS OF THE INTERMOUNTAIN WEST...

...SUMMARY...
An isolated severe risk is forecast later today into the evening for
the Carolinas into northern Georgia, northern Iowa, parts of the
central High Plains, and parts of the Intermountain West.

...Carolina Piedmont into Northern Georgia...
Recent surface analysis places a wavy stationary front from southern
IL through southern IN and southern OH into southwest PA. Decaying
showers and thunderstorms currently precede this boundary from
southern IL into northern KY. This boundary is forecast to shift
southward today in response to a modest surge of cooler air in the
wake of a shortwave trough moving through southern Quebec and the
Canadian Maritimes. This front will be relatively weak, but
thunderstorm development is still anticipated this afternoon as the
front interacts with the warm, moist, and diurnally destabilized
airmass across the Carolina Piedmont and northern GA. Vertical shear
will be weak and a largely outflow-dominant storm mode is expected.
Even so, the strong buoyancy and ample moisture (i.e. PW values over
2 inches) will support the potential for occasionally strong
downbursts.

...Central High Plains...
Water-vapor imagery continues to show a convectively enhanced
vorticity maximum moving north-northeast from north-central NM into
southern CO. This vorticity max is forecast to continue
northeastward along the periphery of the upper ridging centered over
east TX, contributing to thunderstorm development from eastern WY
through eastern CO this afternoon/evening. Much of this activity
will occur in regions of cooler surface temperatures and/or more
limited low-level moisture. However, surface-based buoyancy could
exists in the CO/NE/KS border intersection vicinity, where a
combination of strong heating, and lingering post-frontal low-level
moisture will exist. Potential exists for initially isolated to
widely scattered storms to grow upscale into a small,
eastward-moving cluster this evening. Isolated severe gusts may
accompany the stronger outflow surges with this activity.

...Intermountain West...
Continued thunderstorm development is anticipated across the region
today, with overall coverage and intensity increasing as a shortwave
trough continues to move eastward into southern ID and northern UT.
Some moderate, filtered daytime heating is possible, but the overall
region is expected to remain relatively cool (i.e. high temperatures
ranging from the upper 60s across southern ID to the low to mid 70s
across northern UT). Even so, cold temperatures aloft will support
enough buoyancy, which will combine with strong deep-layer vertical
shear to support occasionally strong/organized updrafts. Strong to
severe gusts will be possible with any stronger, more persistent
storms. Some instances of small hail are possible as well.

...Northern Iowa into Far Southern MN...
Elevated thunderstorm development is still anticipated tonight,
supported by warm-air advection associated with a moderate low-level
jet that extends through the region. Highest storm coverage will
likely be displaced north and east of the strongest buoyancy. Even
so, a few of the southernmost storms could occur where moderate
vertical shear and buoyancy are in place, supporting the potential
for an isolated supercell or two. Primary risk with any stronger
storms is hail, but a strong gust or two is possible if any more
linear structures develop.

..Mosier/Chalmers.. 09/18/2026


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SPC Sep 18, 2026 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook


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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SPC Sep 18, 2026 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1255 AM CDT Fri Sep 18 2026

Valid 181200Z - 191200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE CAROLINAS INTO NORTHERN GEORGIA...IN THE MID MISSOURI VALLEY AND
IN THE INTERMOUNTAIN WEST...

...SUMMARY...
Thunderstorms with isolated severe wind gusts may develop late this
afternoon and early this evening from the Carolinas into northern
Georgia, and in the mid Missouri Valley. Isolated severe gusts and
hail will also be possible in parts of the Intermountain West.

...Carolinas/Northern Georgia...
At the surface, a cold front will move southward into the
Mid-Atlantic today. Ahead of the front, a moist airmass will be in
place over much of the Carolinas extending southwestward into
northern Georgia. Surface dewpoints within this airmass will be in
the 60s to near 70 F. As surface temperatures warm today, an axis of
moderate instability will develop along the moist axis. In response
to surface heating, scattered thunderstorms will form in the higher
terrain of the southern Appalachians and move southward into the
southern Appalachian foothills. The thermodynamic environment may be
enough to support an isolated wind-damage threat, mainly in the late
afternoon and early evening when low-level lapse rates become
steepest.

...Eastern Nebraska/Iowa...
Mid-level heights will gradually fall today over much of the
north-central U.S., as a ridge pattern breaks down. At the surface,
a well-defined moist axis will be in place from the mid Mississippi
Valley northwestward into the mid Missouri Valley. Surface dewpoints
along and near this axis will be in the lower to mid 70s F. In
response to surface heating, a reservoir of moderate instability
will be in place by afternoon over much of Iowa. Low-level
convergence is forecast to become maximized during the afternoon
along the instability axis, and further west to near a surface low
over the mid Missouri Valley. Thunderstorm development will be most
likely this afternoon on the northern end of the stronger
instability from far southeast Minnesota into northern Iowa. Enough
instability and deep-layer shear should be in place for isolated
severe wind gusts. Although conditional, the threat could develop
southwestward over the remainder of Iowa during the early evening,
as a low-level jet strengthens across the region.

...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.

..Broyles/Thornton.. 09/18/2026


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