SPC Sep 5, 2026 2000 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 2000Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Sat Sep 05 2026

Valid 052000Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CAROLINAS INTO SOUTHEASTERN VIRGINIA...

...SUMMARY...
The threat of strong to severe thunderstorms capable of producing
scattered damaging winds will continue this afternoon/evening across
parts of the Carolinas and southern Virginia. Isolated large hail
and severe winds may also occur over parts of the northern/central
Plains through tonight.

...20Z Update...
Only minor changes were made with this update. The SLGT Risk was
trimmed behind an east-southeastward moving band of convection
moving across the Carolinas. While isolated redevelopment cannot be
entirely ruled out in the wake of this activity, the primary severe
risk will continue spreading eastward to the coast into this
evening.

Farther west, 5-percent hail probabilities were added in parts of
the lower OH Valley. Here, relatively steep deep-layer lapse rates,
around 30 kt of effective shear, and a cellular mode may support
isolated instances of marginally severe hail.

Elsewhere, the previous forecast remains on track.

..Weinman.. 09/05/2026

.PREV DISCUSSION... /ISSUED 1122 AM CDT Sat Sep 05 2026/

...Ohio Valley/Central Appalachians into the Mid-Atlantic and
Carolinas...
An earlier MCS across the OH Valley has weakened as it crossed/moved
eastward over the central Appalachians. The strongest remaining
convective segment is ongoing late this morning across parts of
southwest VA/northeast TN. Robust destabilization is expected to
continue this afternoon downstream of this activity across southern
VA into the Carolinas, with MLCAPE peaking around 2500-3500 J/kg
over central/eastern NC. This region will be on the southern
periphery of modestly enhanced mid-level west-northwesterly flow,
and sufficient deep-layer shear will be present to maintain some
convective organization.

Current expectations are for one or more thunderstorm clusters to
gradually increase in intensity this afternoon as they spread
eastward across southern VA and central/eastern NC, with some
uncertainty whether the ongoing convection will restrengthen, or if
new development will occur along its outflow. Regardless, latest
guidance and observational trends still suggest that a relatively
greater threat for damaging winds should exist this afternoon across
central/eastern NC and vicinity, where the greatest thunderstorm
coverage, maxima in MLCAPE/DCAPE, and steepened low-level lapse
rates are forecast. Have therefore introduced higher severe wind
probabilities (30% area) across this region. Isolated hail may also
occur with the strongest cores that can develop, although mid-level
lapse rates are expected to remain rather poor. Severe potential
should gradually wane this evening with the loss of daytime heating,
and as convection moves offshore.

Farther west, outflow from the morning thunderstorms may serve as a
focus for renewed thunderstorm development this afternoon from parts
of the OH Valley southeastward into the TN Valley. This region will
be displaced from the stronger flow aloft present over the
Mid-Atlantic/Northeast, with weak deep-layer shear expected. Still,
some risk for isolated damaging winds may exist with any loosely
organized cells/clusters that can develop given the presence of
moderate to locally strong instability.

...Northern/Central Plains...
A highly amplified mid/upper-level ridge will remain anchored over
the central CONUS into south-central Canada through the period, with
generally neutral to weakly rising mid-level heights expected over
the northern/central Plains. Ongoing elevated cells across northern
ND may continue to pose an isolated severe hail threat in the short
term, but weakening low-level warm advection should tend to result
in a further decrease in intensity with this activity. Otherwise,
additional isolated to perhaps widely scattered high-based
thunderstorms may develop this afternoon along/east of a surface lee
trough over the northern/central Plains. While mid-level flow and
related effective bulk shear should remain weak, occasional severe
gusts may still occur with convective downdrafts given a well-mixed
boundary layer. Some risk for hail and gusty winds may also exist
with elevated convection that should eventually develop tonight into
early Sunday morning in a renewed/modest low-level warm advection
regime.

...Western Montana...
To the east of a closed mid-level low over WA/OR, a belt of enhanced
southwesterly mid/upper-level winds will extend across the northern
Rockies. Gradually increasing moisture and large-scale ascent aloft
associated with a weak/embedded shortwave trough are expected to
support an increase in isolated thunderstorms this
afternoon/evening. Lapse rates through low/mid levels will be steep
with strong deep-layer shear present, but modest low-level moisture
should limit MLCAPE to generally less than 500 J/kg. The potential
for severe wind gusts still appears too low to justify including 5%
wind probabilities at this time.


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SPC Sep 5, 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
0754 AM CDT Sat Sep 05 2026

Valid 051300Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
THE OHIO VALLEY INTO SOUTHERN MID-ATLANTIC AND CAROLINAS...

...SUMMARY...
Severe thunderstorms capable of mainly damaging gusts are possible
across portions of the Ohio Valley into southern Mid-Atlantic and
Carolinas this afternoon and evening. Isolated occurrences of large
hail and severe wind gusts also appear possible over parts of the
northern and central Plains today into tonight.

...Ohio Valley into the Carolinas...
An MCS continues to progress southeastward towards the central
Appalachians this morning. The outflow has surged well ahead of the
deep convection along the western edge of this MCS, but remains much
closer to the two primary cores of deep convection along the central
and eastern portions of the MCS. General expectation is for this MCS
to continue southeastward across the central Appalachians and into
the Mid-Atlantic, while the westward-progressing outflow stalls and
loses definition.

Currently, the airmass downstream across the Mid-Atlantic is
characterized by dewpoints ranging from the upper 60s across
northern VA into the mid 70s across southeast NC/eastern SC. Strong
heating is anticipated across much of this region today, with high
temperatures ranging from the low 90s over northern to the upper
90s/low 100s across central/eastern SC. These warm and moist surface
conditions will support moderate to strong afternoon buoyancy,
despite poor mid-level lapse rates. Reintensification and/or renewed
thunderstorm development is expected as the MCS (and associated
vorticity maximum) interacts with this destabilized airmass. This
region will be along the southerly periphery of a belt of mid-level
northwesterlies, and the resulting vertical shear could help
maintain a favorable cold pool/updraft balance needed to maintenance
of a progressive convective line. Guidance varies on whether one
coherent convective line or a series of smaller bowing segments will
develop, but either case would yield a threat for damaging gusts.
Highest probability for damaging gusts is expected across eastern NC
where the best overlap between buoyancy and vertical is expected.

Additional afternoon development is expected farther west, from the
middle OH Valley through Middle TN, where residual outflow will
likely be present with a destabilized airmass. Weak shear should
limit storm organization but isolated damaging gusts are possible.

...Northern and Central Plains...
Elevated thunderstorms have persisted throughout much of the night
from northeast NE across eastern SD. A second area of thunderstorm
activity exists farther norther across north-central ND. An isolated
instance of hail is possible over both of these regions for the next
few hours before thunderstorm intensity wanes in response to the
cessation of the nocturnal low-level jet.

Despite rising heights throughout the day, most guidance suggests
that low-level convergence along both the lee trough and
outflow-modified front in NE will be sufficient for convective
initiation this afternoon. Limited vertical shear and a deeply mixed
boundary layer suggest an outflow-dominant storm mode with the
primary hazard being widely-spaced severe wind gusts.

Relatively higher thunderstorm coverage is possible across the
central High Plains this evening as warm-air advection supports
additional thunderstorm activity. Some clustering of this activity
is possible, but vertical shear will be weak and overall storm
intensity and organization should be modest.

...Western Montana...
A belt of enhanced mid/upper-level flow will extend across the
region, to the east of an upper low over the Pacific Northwest.
Increasing mid-level moisture and forcing for ascent associated with
a weak mid-level disturbance is expected to support an increase in
high-based showers and a few thunderstorms during the afternoon and
evening. Lapse rates will be steep with strong deep-layer shear, but
the absence of appreciable moisture will limit MLCAPE to generally
less than 250 J/kg. As such the potential for severe wind gusts is
currently too low to warrant 5% wind probabilities.

..Mosier/Lyons.. 09/05/2026


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SPC Sep 5, 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
1222 AM CDT Sat Sep 05 2026

Valid 051200Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
THE OHIO VALLEY INTO THE SOUTHERN MID-ATLANTIC AND CAROLINAS...

...SUMMARY...
Severe thunderstorms capable of mainly damaging gusts are possible
across portions of the Ohio Valley into southern Mid-Atlantic and
Carolinas on Saturday afternoon and evening. Isolated occurrences of
large hail and severe wind gusts also appear possible over parts of
the northern and central Plains Saturday into Saturday night.

...Synopsis...

A prominent mid-level ridge will persist over the central CONUS
between upper lows over the Pacific Northwest and the Gulf of St.
Lawrence into NB/NS. Several weak disturbances (some of convective
origin) will progress through the periphery of the ridge, serving as
foci for thunderstorm development. At the surface, an area of low
pressure is forecast over the western Dakotas with an associated
boundary --the location of which may be modified by convective
outflow-- extending into the OH Valley and southern Mid-Atlantic.
The eastern extension of the boundary will begin to push south as a
cold front Saturday afternoon into night as high pressure builds
into the Great Lakes.

...Ohio Valley into the Carolinas...

A mature to decaying MCS is expected to be ongoing 12Z Saturday over
portions of the middle to upper OH Valley, aided by a subtle
mid-level disturbance/possible MCV. There is considerable
variability across the 00Z convection-allowing models in the
longevity and extent of the convective system over the central
Appalachians into southern Mid-Atlantic through the remainder of the
morning. Should the MCS remain intact, isolated occurrences of
damaging wind are possible.

Renewed thunderstorm development is likely by afternoon along the
residual MCS cold pool and/or synoptic front as temperatures in the
90s to around 100 combine with boundary-layer dewpoints in the low
to mid 70s to yield MLCAPE up to 2000-3000+ J/kg with steepening
low-level lapse rates. Additionally, the models indicate some
enhancement of mid-level winds in association with the
disturbance/MCV moving through the southern Mid-Atlantic during the
afternoon, which may yield more organized multicells and line
segments with the predominant hazard being damaging wind gusts into
the evening.

Farther to the west, additional strong to severe storms appear
possible along and ahead of the composite boundary from the vicinity
of the OH River south into the Cumberland Plateau where widely
scattered damaging wind gusts also appear possible.

...Northern and Central Plains...

A band of elevated thunderstorms is expected to be ongoing 12Z
Saturday, centered over eastern SD. That activity is expected to
diminish through the morning with the cessation of the nocturnal
low-level jet; however, isolated occurrences of large hail and
severe wind gusts appear possible prior to dissipation. In the wake
of the early-day storms, the presence of steep low/mid-level lapse
rates and richer boundary-layer moisture with eastward extent will
contribute to a moderately to strongly unstable air mass by
afternoon with MLCAPE of 2000-3500+ J/kg.

Nebulous forcing for ascent and capping relating to the proximity of
the mid-level ridge axis lead to uncertainty in the specific details
regarding the location and extent of surface-based thunderstorm
development during the afternoon into evening. However, the presence
of the surface low, outflow-modified surface front, and a lee trough
over the High Plains will be candidates for storm development. The
strongest deep-layer shear (30-40 kt) is forecast to the north of
the surface low and composite boundary over ND and northern SD into
western MN where a conditional risk of supercells capable of large
hail and severe wind gusts exists. Elsewhere, high-based pulse and
multicell storm modes appear possible with the primary hazard being
widely-spaced severe wind gusts.

The isolated severe threat may persist into the overnight hours in
the vicinity of a nocturnally strengthening low-level jet.

...Western Montana...

A belt of enhanced mid/upper-level flow will exist across the
region, to the east of the upper low over the Pacific Northwest.
Heating along the high terrain coupled with the possible influence
of a weak mid-level disturbance is expected to support an increase
in high-based showers and a few thunderstorms during the afternoon
and evening. While lapse rates will be steep with strong deep-layer
shear, the absence of appreciable moisture will limit MLCAPE to
generally less than 250 J/kg. As such the potential for severe wind
gusts is currently too low to warrant 5% wind probabilities.

..Mead/Chalmers.. 09/05/2026


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SPC Sep 5, 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
0753 PM CDT Fri Sep 04 2026

Valid 050100Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE SOUTHERN GREAT LAKES INTO THE MID AND UPPER OHIO VALLEY...

...SUMMARY...
Severe storms capable of scattered occurrences of damaging wind with
gusts up to 70 mph are expected across the southern Great Lakes and
mid/upper Ohio Valley overnight. More isolated severe storms capable
of large hail and severe wind gusts may occur over portions of the
northern Plains. Strong to severe storms with a risk for damaging
wind gusts may persist for another couple of hours in the southern
Mid-Atlantic.

...Great Lakes into the Ohio Valley...

Forcing for ascent attendant to a weak mid-level disturbance
cresting the mid-level ridge is contributing to a couple of areas of
thunderstorm activity this evening over portions of eastern IA and
central WI. The 00Z DVN sounding is likely representative of the
inflow air mass for these storms, featuring a moist boundary layer
and relatively steep mid-level lapse rates with MLCAPE of around
4000 J/kg. It remains unclear whether a subset of the current storms
will grow upscale into a cold-pool-driven MCS overnight, or whether
additional storms will develop farther to the east across portions
of southern Lake MI and southwest Lower MI in the next few hours.
Either way, there is a consistent model signal for a bowing
convective system to evolve across portions of northeast IN into OH,
along the cool side of a composite surface boundary extending from
central WI through central IN into eastern KY.

Regional VWPs and 00Z soundings indicate the presence of 30-35 kt
northwest winds in the mid levels along the axis of the prospective
MCS track, which will contribute to sufficient deep-layer shear for
cold-pool organization. As such, a corridor of more concentrated
wind damage appears possible along with severe gusts up to 70 mph.

...Northern Plains...

A cluster of mainly elevated thunderstorms is ongoing this evening
over north-central SD, with that activity likely rooted above a warm
capping inversion observed by the 00Z ABR sounding. Additional
storms are expected to develop overnight along a nocturnally
strengthening low-level jet, where warm advection and moisture
transport will be maximized. Mid-level flow and resultant vertical
shear are forecast to weaken overnight owing to the proximity of the
mid-level ridge. However, the presence of steep mid-level lapse
rates and associated moderate to strong instability suggests the
potential for isolated severe storms capable of large hail and
severe wind gusts. As such, 5% wind and hail probabilities have been
included in this forecast update.

...Southern Mid-Atlantic...

Clusters of strong to severe thunderstorms ongoing over portions of
southeast VA into north-central and northeast NC will remain capable
of mainly damaging wind gusts for the next hour or two. Thereafter,
storms are expected to gradually weaken as the boundary layer
stabilizes.

..Mead.. 09/05/2026


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