SPC Sep 13, 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
1258 AM CDT Sun Sep 13 2026

Valid 131200Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
OHIO VALLEY INTO THE NORTHEAST...AND ALSO ACROSS PARTS OF THE
CENTRAL/NORTHERN HIGH PLAINS...

...SUMMARY...
Strong to locally severe storms are possible across parts of upper
Ohio Valley and Northeast this afternoon and evening. Isolated
strong to severe storms are also possible across parts of the
central and northern High Plains.

...Parts of the Ohio Valley to the Northeast...
A mid/upper-level trough is forecast to amplify as it moves across
the Great Lakes region toward the Northeast through tonight. A
surface low will move across Quebec, as a trailing cold front moves
through the eastern Great Lakes and Northeast this afternoon and
evening. The strongest deep-layer flow and large-scale ascent will
tend to lag the cold front, but some strengthening of flow in the
700-500 mb layer is expected across the warm sector this afternoon,
resulting in favorable wind profiles for organized convection.

Moderate buoyancy is expected to develop by late afternoon as CINH
weakens, and widely scattered storm development is eventually
expected along/ahead of the front. Despite the favorable wind
profiles, weak midlevel lapse rates and modest ascent may tend to
limit updraft intensity. Guidance continues to vary regarding the
magnitude of severe potential, with the 00Z HRRR/RRFS more
aggressive in developing organized convection (and possible
supercells), while other HREF guidance depicts generally weak
convection.

Localized damaging wind and isolated hail may accompany the
strongest storms. If later observational and guidance trends support
the more aggressive scenario, then greater severe probabilities may
eventually be needed.

...Central/northern High Plains...
A mid/upper-level low/trough initially over the Pacific Northwest
will move toward the northern Rockies and High Plains through the
period. Diurnal destabilization will generally be limited ahead of
this trough, though a narrow zone of moderate buoyancy may develop
by late afternoon from northeast CO into southeast WY and the NE
Panhandle. Isolated storm development will be possible, with
sufficient deep-layer shear for at least transient storm
organization and isolated severe hail/wind potential.

While any diurnal storms may tend to weaken through the evening,
elevated convection is expected to increase in coverage across
western/central SD tonight. Moderate elevated buoyancy and
sufficient effective shear could support an isolated severe threat
with the initial elevated storm development across western SD,
though storm interference and weakening buoyancy may tend to limit
the longevity and eastward extent of the threat.

...Parts of MT into northwest ND...
Increasing ascent associated with the approaching mid/upper-level
low/trough will result in elevated storm development this evening
across MT, which will spread into northwest ND overnight. Generally
weak buoyancy is currently expected to limit organized severe
potential, though small hail and locally gusty winds could accompany
the strongest storms.

..Dean/Halbert.. 09/13/2026


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SPC Sep 13, 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 Sat Sep 12 2026

Valid 130100Z - 131200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTH-CENTRAL PLAINS...

...SUMMARY...
Strong to severe storms capable of severe wind gusts and isolated
hail remain possible tonight across parts of the south-central
Plains.

...South-central Plains and vicinity...
Isolated strong to severe storms are ongoing this evening from
southwest KS into northwest OK and the TX Panhandle, with another
persistent storm cluster across eastern KS. Earlier storm
development across central/northwest OK was driven by very strong
heating in the vicinity of an outflow boundary, within a regime of
generally weak deep-layer flow/shear. This activity is expected to
generally weaken through late evening, due to the onset of nocturnal
cooling/stabilization. However, isolated hail and strong to severe
gusts will remain possible with any remaining storms through
mid/late evening.

Another surface boundary is located across southern KS, with moist
low-level easterly flow in place between this boundary and the
outflow boundary across OK. Short-term CAM guidance continues to
depict persistence of strong to locally severe storms through late
evening within this regime from southern KS into far northern OK and
perhaps southwest MO, potentially aided by a modest strengthening of
the nocturnal low-level jet. While this convection may tend to
become increasingly elevated with time, favorable lapse rates and
buoyancy and sufficient deep-layer shear (as depicted on the 00Z DDC
sounding) will support vigorous cells and perhaps a loosely
organized cluster, with potential for strong to severe gusts and
isolated hail.

See MCDs 2290 and 2291 for more information regarding the short-term
threats in this region.

..Dean.. 09/13/2026


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SPC Sep 12, 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
1135 AM CDT Sat Sep 12 2026

Valid 121630Z - 131200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTH-CENTRAL PLAINS...

...SUMMARY...
Isolated to scattered severe thunderstorms capable of producing
large to very large hail and severe/damaging winds may occur across
parts of the south-central Plains into the Ozarks this afternoon and
evening.

...Central/Southern Plains to the Ozarks...
Scattered mainly elevated thunderstorms continue at midday across
the region, including the strongest/occasionally-severe storms
across southeast Nebraska into northeast Kansas that are occurring
near/just behind a southeastward-moving cold front. Some severe hail
will remain possible as these storms continue southeastward on the
edge of the primary instability reservoir.

This front, augmented by early day outflows, will otherwise serve as
a focus for more robust thunderstorm development this
afternoon/evening as well. With a rather moist low-level airmass
forecast to be present along/south of the front, current
expectations are for a narrow zone of moderate to strong instability
(MLCAPE 2000-3500 J/kg) to develop this afternoon from the eastern
Oklahoma/Texas Panhandles across southern Kansas and northern
Oklahoma. Weak low-level winds will veer to west-northwesterly and
strengthen some with height through mid/upper levels, supporting
around 30-40 kt of deep-layer shear and updraft organization. While
large-scale ascent will remain fairly weak/nebulous across the
southern/central Plains, most guidance shows at least isolated
robust thunderstorm development along the front by 21-23Z as
convective temperatures are reached.

Any sustained supercells would pose a threat for large to very large
hail, with steep mid-level lapse rates and ample instability in the
hail-growth zone supporting potential for 2+ inch
diameter hail on an isolated basis. Somewhat higher-based convection
is expected from the eastern Oklahoma/Texas Panhandles into
southwest/south-central Kansas and northern Oklahoma, where a very
well-mixed boundary layer with steep low/mid-level lapse rates
will promote an environment that supports severe-caliber downdraft
winds. Some gusts could exceed 75 mph. A degree of storm clustering
could occur into this evening.

...Upper Ohio Valley...
A regional pocket of relatively cloud-free skies at midday will
contribute to filtered diurnal heating and moderate instability
across the region. Thunderstorms will further increase in coverage
and intensity through the afternoon, aided by forcing for ascent
associated with an approaching weak mid-level shortwave trough.
While mid-level lapse rates will remain poor, sufficient deep-layer
shear coupled with modest steepening of low-level lapse rates
suggest some risk for occasional damaging winds with any loosely
organized clusters/line segments that develop.

..Guyer/Wendt.. 09/12/2026


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SPC Sep 12, 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
0748 AM CDT Sat Sep 12 2026

Valid 121300Z - 131200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL/SOUTHERN PLAINS...

...SUMMARY...
Isolated to scattered severe thunderstorms capable of producing
large to very large hail and severe/damaging winds may occur across
parts of the central/southern Plains into the Ozarks this afternoon
and evening.

...Central/Southern Plains into the Ozarks...
Mainly elevated thunderstorms have persisted overnight into the
early morning across southern NE into eastern KS/western MO, aided
by a modest low-level jet. This activity will probably tend to
weaken through the remainder of the morning, but some recent
guidance suggests additional thunderstorms developing along its
outflow across southern KS/northern OK over the next few hours. If
this development occurs, it would potentially complicate
destabilization and severe potential later today. Recent surface
observations also show a fairly strong cold front draped from
eastern CO into KS and northwest MO. This boundary will likely serve
as a focus for robust thunderstorm development this
afternoon/evening as well. With a rather moist low-level airmass
forecast to be present along/south of the front, current
expectations are for a narrow zone of moderate to strong instability
(MLCAPE 2000-3500 J/kg) to develop this afternoon from the eastern
OK/TX Panhandles into southern KS/northern OK. Weak low-level winds
will veer to west-northwesterly and strengthen some with height
through mid/upper levels, supporting around 30-40 kt of deep-layer
shear and updraft organization. While large-scale ascent will remain
fairly weak/nebulous across the southern/central Plains, most
guidance shows at least isolated robust thunderstorm development
along the front by 21-23Z as convective temperatures are reached.

While there is still uncertainty regarding convective evolution and
persistence of ongoing thunderstorms this morning, some signal
exists in most recent short-term guidance that isolated to scattered
convection will form along much of the length of the front later
today in a rather favorable environment to support severe
thunderstorms. Any sustained supercells would pose a threat for
large to very large hail, with steep mid-level lapse rates and ample
instability in the hail-growth zone supporting potential for 2+ inch
diameter hail on an isolated basis. Somewhat higher-based convection
also appears probable from the eastern OK/TX Panhandles into parts
of southwest/south-central KS and northern OK, where a very
well-mixed boundary layer with steep low/mid-level lapse rates
should promote an environment that supports scattered severe
downdraft winds. Some gusts could exceed 75 mph. The potential for
clustering this afternoon and evening remains unclear, but some
chance for at least isolated severe/damaging winds may persist into
much of OK and the Ozarks, dependent on upstream convective
evolution in KS/western MO.

...Upper Ohio Valley...
A narrow corridor of filtered diurnal heating and related moderate
instability should develop across parts of the upper OH Valley this
afternoon between denser clouds and precipitation occurring across
OH, and a stationary boundary to the east. Thunderstorms will
gradually increase in coverage and intensity through the afternoon,
aided by forcing for ascent associated with an approaching weak
mid-level shortwave trough. While mid-level lapse rates will remain
poor, sufficient deep-layer shear coupled with modest steepening of
low-level lapse rates suggest some risk for occasional damaging
winds with any loosely organized clusters/line segments that can
form.

..Gleason/Lyons.. 09/12/2026


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