SPC Sep 6, 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 Sun Sep 06 2026

Valid 062000Z - 071200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHEAST...MONTANA...AND THE MISSOURI VALLEY...

...SUMMARY...
Scattered damaging winds should occur across parts of the Southeast
this afternoon/early evening. Scattered large hail is forecast
across portions of Montana this afternoon and evening. A focused
corridor for damaging winds and severe hail is forecast across parts
of the Middle and Lower Missouri Valley. Isolated strong to severe
thunderstorms may also occur today across parts of the northern
Great Basin, northern/central Plains, and the Ozarks.

...20Z Update...
A Slight Risk was added across parts of the Middle and Lower
Missouri Valley -- driven by 15-percent wind and hail probabilities.
Here, ample diurnal heating amid a very moist air mass is yielding a
corridor of strong surface-based buoyancy (around 4000 J/kg MLCAPE
per the latest HRRR SFCOA data). Large-scale ascent preceding a
convectively augmented midlevel impulse should promote an increase
in storm coverage in this north/south corridor through the
afternoon. The strong buoyancy and around 30 kt of effective shear
should promote a mix of organized clusters and possibly some
supercell structures -- capable of producing damaging wind gusts and
severe hail. See MCD #2253 for more details.

Farther north, the Slight Risk in ND was removed. The latest mode
evolution suggests a reduced hail threat compared to this morning.
However, a locally favorable corridor for damaging wind gusts may
develop into parts of eastern ND this afternoon/early evening.

Elsewhere, the previous forecast remains on track.

..Weinman.. 09/06/2026

.PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Sep 06 2026/

...Southeast/Lower Mississippi Valley...
Recent visible satellite imagery shows mostly clear skies across
GA/SC late this morning, with surface temperatures already in the
mid/upper 80s to low 90s. A weak front is draped from northwest to
southeast from the southern Appalachians to the Atlantic Coast, with
generally low to mid 70s surface dewpoints present to its south.
Continued diurnal heating of this moist airmass will support the
development of moderate to strong instability (greater with
southward/westward extent into GA/AL and north FL). Compared to the
past couple of days, this region will be displaced from the stronger
mid-level west-northwesterly flow present across the
Mid-Atlantic/Northeast. Corresponding deep-layer shear is expected
to remain rather modest (less than 25 kt), with only loosely
organized updrafts forecast. Even with these kinematic limitations,
steepening low-level lapse rates through the afternoon may still
promote isolated to scattered damaging winds with clusters that
develop and spread south-southeastward through the early evening.
Isolated hail may also occur with the more robust cells that can
develop initially. The damaging wind threat should be more isolated
with westward extent into the lower MS Valley compared to GA and the
Carolinas, where the Slight Risk has been maintained with some
expansion.

...Northern Great Basin into the Northern Rockies/High Plains...
A closed mid/upper-level low over the Pacific Northwest and British
Columbia will pivot towards the northern Rockies through the period,
with a belt of enhanced mid-level flow overspreading the northern
Great Basin into the northern Rockies and adjacent High Plains in
MT. At the surface, mostly cloudy conditions are present over much
of western/central MT this morning. Even so, recent NAM/RAP forecast
soundings across this region show supercell profiles later this
afternoon and evening as mid/upper-level winds foster strong
deep-layer shear. Current expectations are for multiple supercells
to develop initially over the higher terrain and spread quickly
northeastward. While there is still some uncertainty regarding
boundary-layer destabilization, sufficient MUCAPE is forecast to
support supercell maintenance into the adjacent High Plains through
the evening. Large hail should be the main threat with this activity
(with some 2+ inches possible given the very favorable deep-layer
shear), but isolated severe gusts may also occur. The Slight Risk
has been adjusted/expanded a little eastward in MT based on latest
short-term guidance trends. High-based thunderstorms may also pose
an isolated threat for severe gusts across parts of the northern
Great Basin this afternoon.

...Northern/Central Plains into the Upper Midwest/Missouri Valley
and Ozarks...
Ongoing and likely elevated supercells with a threat for large hail
across parts of western ND are being aided by a subtle mid-level
shortwave trough cresting the upper ridge that is anchored over the
central CONUS. Favorable lapse rates aloft and modestly enhanced
mid/upper-level southwesterly flow is likely supporting updraft
organization/intensity with this ongoing activity. The airmass
downstream across central/eastern ND should gradually destabilize
through the afternoon, with a moist low-level airmass present to the
east of a weak surface low over eastern MT/southwest ND/northwest
SD. It remains unclear whether these ongoing supercells will be
maintained farther east across ND, but given the favorable airmass
and sufficient deep-layer shear present, have opted to add a
targeted Slight Risk for the large hail potential.

Additional convection is occurring farther south in SD, southwest
MN/northwest IA, and northeast NE in association with a mid-level
vorticity maximum evident on water vapor satellite imagery moving
eastward across SD/NE. There is a narrow corridor of greater
instability present across this region southward to the Ozarks,
generally along/near a weak surface front. Isolated hail may occur
with the stronger cores in the short term, but it remains unclear if
convection will be able to form into a southward-moving cluster
across eastern NE/western IA later this afternoon and evening. If
this does occur, then a greater threat for severe/damaging winds
would exist. Have deferred a possible upgrade to Slight Risk given
the uncertainty with how ongoing convection will evolve/impact the
developing warm sector, and due to the presence of the large-scale
mid/upper-level ridge and generally modest flow aloft. A separate
area of high-based thunderstorms that should develop this afternoon
along/east of a surface lee trough across the central High Plains
could produce occasional hail and severe gusts, even as deep-layer
shear remains modest.


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TVM65t

SPC Sep 6, 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
0751 AM CDT Sun Sep 06 2026

Valid 061300Z - 071200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE SOUTHERN APPALACHIANS INTO THE SAVANNAH RIVER VALLEY...AND OVER
PARTS OF WESTERN AND CENTRAL MONTANA...

...SUMMARY...
Widely scattered damaging wind gusts are likely across portions of
the Southeast this afternoon and early evening. Widely scattered
large hail occurrences are expected across portions of western and
central Montana this afternoon and evening. Additional areas at risk
for isolated severe wind and hail are parts of the Interior West,
over the northern and central High Plains, and from the eastern
Dakotas and western Minnesota into the Ozark Plateau and Gulf Coast
states.

...Southern Appalachians through coastal SC and GA...
A moist airmass is in place across the region this morning, with
recent surface analysis revealing a reservoir of low to mid 70s
dewpoints. Strong heating is anticipated across this region today,
with afternoon temperatures reaching the low to mid 90s. This strong
heating will destabilize the airmass and contribute to
moderate/strong buoyancy, with MLCAPE around 2000-2500 J/kg likely
during the late afternoon. A subtle shortwave trough will progress
through the northwesterly flow aloft extending over the area,
interacting with this destabilized airmass to support thunderstorm
development. Vertical shear will generally be weak, limiting updraft
organization and promoting a predominantly outflow-dominant storm
mode. Even so, steep low-level lapse rates and abundant moisture
will promote the potential for damaging wind gusts with any
longer-lived multi-cells or line segments. Updraft augmentation due
to storm interactions could also result in isolated hail.

...Ozark Plateau into the Gulf Coast States...
A corridor of greater low-level moisture arcs from the Southeast
states through Arkansas and Missouri. Daytime heating will
destabilize this airmass, helping to support thunderstorm
development in areas of low-level confluence. Weak forcing for
ascent and vertical shear are expected to limit storm organization.
However, the degree of instability will support briefly intense
pulse-type storms capable of locally damaging wet microbursts during
the afternoon and early evening hours.

...Eastern Dakotas and western Minnesota into the lower Missouri
Valley...
A linear MCS continues to push eastward across the central Plains
this morning. A notable vorticity maximum has developed within the
northern portion of this line. Its motion appears to be more
northeasterly than the line itself, and new development is occurring
downstream of this vorticity maximum across south-central/southeast
SD and adjacent northeast NE. A corridor of relatively greater
low-level moisture (i.e. dewpoints in the low 70s) exists downstream
of this vorticity maximum and attendant MCS from eastern SD through
western IA and into northern MO. General expectation is for
thunderstorm coverage and intensity to increase later this
morning/early afternoon as the vorticity maximum/remnant MCS
interact with this moist and diurnally destabilizing airmass. Much
of this development is expected to occur along or to the immediate
cool side of the surface boundary that extends through portions of
the middle and lower MO Valley. Occasionally strong updrafts could
result in isolated hail and/or damaging gusts, but the weak
mid-level flow and associated modest deep-layer shear should limit
storm organization and contribute to clustered multicellular mode.

...Northern Plains into the northern/central High Plains...
Modest height falls may begin to impinge on northern/central High
Plains during the early evening as a low-amplitude shortwave trough
moves a belt of stronger southwesterlies just west of the region.
This modest ascent will augment low-level convergence along the lee
trough to support isolated to widely scattered thunderstorm
development where the lingering convective inhibition can be
overcome. This appears most likely across southeast WY and northeast
CO where persistent low-level easterly flow could keep dewpoints in
the 60s. High-based, outflow-dominant storms will support the
potential for isolated strong to severe gusts.

Increasing mid-level flow will support stronger deep-layer vertical
shear farther north (into eastern MT and western ND), but stronger
convective inhibition may linger, casting doubt whether storms will
initiate. If initiation is realized, storm motion could take it into
the more moist and buoyant airmass north of the surface low where
thermodynamic profiles are favorable for large to very large hail.
Will maintain 5% wind/hail probabilities but introduce a CIG1 for
hail given the conditional potential.

...Northern Great Basin into the northern Rockies...
Increasing height falls and strengthening mid/upper-level flow will
spread across the region today ahead of a vigorous shortwave trough
pivoting through the base of a Pacific Northwest upper low.
Thunderstorm development is anticipated over the higher terrain
before then progressing northeastward towards lower elevations.
Deep-layer vertical shear of 40 to 50 kt will support supercells,
with large hail as the primary severe risk. Greater buoyancy is
expected across central MT, but low-level stability will likely
persist across this region as well, potentially limiting the
severe-wind and tornado potential.

Weaker instability is forecast from northeast NV and northern UT
into central and eastern ID. However, the presence of steep lapse
rates and kinematics mentioned above may yield a few severe storms
capable of severe wind gusts.

..Mosier/Lyons.. 09/06/2026


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TVLy8r

SPC Sep 6, 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
1241 AM CDT Sun Sep 06 2026

Valid 061200Z - 071200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE SOUTHERN APPALACHIANS INTO THE SAVANNAH RIVER VALLEY AND OVER
PARTS OF WESTERN AND CENTRAL MONTANA...

...SUMMARY...
Widely scattered damaging wind gusts are likely across portions of
the Southeast Sunday afternoon and early evening. Widely scattered
large hail occurrences are expected across portions of western and
central Montana Sunday afternoon and evening. Additional areas at
risk for severe wind and hail are across parts of the Interior West,
over the northern and central High Plains, and from the eastern
Dakotas and western Minnesota into the Ozark Plateau and Gulf Coast
states.

...Synopsis...

A prominent mid-level ridge over the central U.S. is forecast to
weaken during the latter half of the period in response to the
progression of two distinct short-wave troughs and associated wind
maxima through the Interior West. Separate, weaker perturbations
will move through the ridge axis over the northern Plains/mid-MO
Valley region on Sunday, contributing to thunderstorm development in
those areas. Elsewhere, a mid-level disturbance over the OH Valley
Sunday morning is forecast to move into the Cumberland Plateau
vicinity by afternoon, also likely serving as a focus for
thunderstorm development.

At the surface, a lee cyclone will persist over the northern High
Plains, with that feature potentially deepening Sunday night in
response to increasing height falls aloft. High pressure will build
across the Great Lakes, OH Valley, and Northeast with a baroclinic
zone present between those surface features from the mid-MO Valley
through the Ozarks and TN Valley into the Southeast.

...Southern Appalachians into the Savannah River Valley...

Temperatures in the 90s will coincide with boundary-layer dewpoints
in the 70s to yield a moderately to strongly unstable air mass
(i.e., MLCAPE of 2000-3000+ J/kg) by afternoon with steepening
low-level lapse rates. Aided by forcing attendant to the mid-level
disturbance mentioned above, that thermodynamic environment will
support an increase in thunderstorm coverage and intensity through
the afternoon along and ahead of the surface front.

Some increase in mid-level winds may accompany the disturbance with
up to 30 kt of deep-layer shear forecast in the vicinity of the
frontal zone. As such, the potential will exist for longer-lived
multi-cells and line segments capable of damaging wind gusts and
perhaps some large hail into evening.

...Ozark Plateau into the Gulf Coast States...

A similar thermodynamic environment to that previously described is
anticipated ahead of the surface front Sunday afternoon. Generally
weak forcing for ascent and vertical shear are expected to limit the
potential for a more organized severe weather threat. However, the
degree of instability will support briefly intense pulse-type storms
capable of locally damaging wet microbursts during the afternoon and
early evening hours.

...Northern Great Basin into the northern Rockies...

Increasing height falls and strengthening mid/upper-level flow will
overspread the region Sunday afternoon into night ahead of a
vigorous short-wave trough pivoting through the base of the Pacific
Northwest upper low. The strongest instability (i.e., MLCAPE up to
1000-1500 J/kg) is forecast across portions of western into central
MT with stronger capping with eastward extent. The presence of 40-50
kt of deep-layer shear will support supercells capable of mainly
large hail through Sunday evening. While forecast hodographs exhibit
considerable curvature/veering winds in the lowest 1-2-km AGL,
stability concerns in the boundary layer may limit severe-wind-gust
and tornado potential.

Weaker instability is forecast from northeast NV and northern UT
into central and eastern ID. However, the presence of steep lapse
rates and kinematics mentioned above may yield a few severe storms
capable of severe wind gusts.

...Northern and central High Plains...

Stronger forcing for ascent is expected to remain to the west and
east of the region through the daylight hours, leading to
uncertainty in storm coverage in the vicinity of the surface low and
lee trough. The 00Z models indicate an increasing potential for at
least isolated thunderstorms from mid-afternoon into evening along
the lee trough. RAP-based forecast soundings show steep lapse rates
and resulting MLCAPE of 1000-2000+ J/kg. The strongest deep-layer
shear of 40-50 kt is forecast across eastern MT into ND with
decreasing magnitudes with southward extent along the lee trough. As
such, a conditional risk for supercells capable of large hail and
severe wind gusts exists. While Marginal Risk wind and hail
probabilities will be maintained with this forecast, an upgrade to
level 2/Slight Risk is possible in subsequent updates.

...Eastern Dakotas and western Minnesota into the lower Missouri
Valley...

Clusters of mainly elevated thunderstorms may be ongoing at 12Z
Sunday, aided by forcing associated with the weak disturbance(s)
cresting the mid-level ridge axis. A subset of the early-day storms
is expected to persist into afternoon with additional storms forming
on the leading edge of more persistent cloud cover, where pockets of
stronger heating and boundary-layer dewpoints in the low/mid 70s
will yield MLCAPE of 1500-2500 J/kg. The 00Z models suggest that
storms will eventually grow upscale into an MCS that tracks south
along or to the immediate cool side of the surface boundary through
portions of the middle and lower MO Valley Sunday afternoon into
evening. It currently appears that deep-layer shear of generally
less than 30 kt and marginally steep mid-level lapse rates may limit
the degree of cold pool organization and a greater/more continuous
damaging-wind threat. Nonetheless, the setup appears supportive of
sporadic damaging wind and severe hail occurrences.

..Mead/Chalmers.. 09/06/2026


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TVLmlc

SPC Sep 6, 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
0756 PM CDT Sat Sep 05 2026

Valid 060100Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER NORTHEAST
COLORADO INTO PARTS OF WESTERN NEBRASKA...INCLUDING THE PANHANDLE...

...SUMMARY...
Widely scattered occurrences of large hail and severe wind gusts are
expected into tonight over northeast Colorado into parts of western
Nebraska, including the Panhandle. Isolated occurrences of large
hail and damaging winds remain possible overnight across a broader
portion of the northern and central Plains. Damaging wind potential
is expected to diminish within the next couple of hours over
portions of Kentucky, Georgia, and South Carolina.

...Northern and Central Plains...

Separate clusters of thunderstorms, including supercells, are
ongoing this evening over the NE Panhandle into northeast CO ahead
of a weak mid-level disturbance moving through WY and north-central
CO. The 00Z LBF sounding sampled relatively steep lapse rates with
MLCAPE of around 2500 J/kg along with a vertically veering wind
profile with around 30 kt of deep-layer shear. As such, expect the
supercell threat to persist for the next hour or two, prior to
storms merging into a larger complex along a nocturnally
strengthening low-level jet. Large hail up to two inches will be the
main hazard in the near-term; however, the potential for severe wind
gusts will become more prevalent if an organized cold pool can
evolve.

Elsewhere, storms are widely scattered across the Dakotas with the
00Z ABR sounding indicating a moderately unstable, but capped air
mass for surface-based parcels. Additional, elevated storms appear
possible overnight along the low-level jet axis with a risk for
isolated occurrence of large hail and damaging wind gusts.

...Central Georgia into southern South Carolina...

Widely scattered thunderstorms are ongoing this evening from south
of Atlanta into southern SC, along an outflow boundary remnant from
storms earlier today. Isolated occurrences of damaging wind gusts
remain possible for the next hour or two before low-level lapse
rates begin to weaken with the loss of daytime heating.

...Kentucky...

A small cluster of thunderstorms has recently intensified south of
the OH River, east of Owensboro, in the vicinity of a weak surface
boundary, and ahead of a weak mid-level disturbance approaching the
area from the north. Regional 00Z soundings indicate the air mass
remains moderately unstable with around 30 kt of deep-layer shear.
The ongoing storms will remain capable of strong wind gusts for the
next hour or so before the boundary layer begins to stabilize.

..Mead.. 09/06/2026


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TVLdCc