SPC Sep 7, 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
0259 PM CDT Mon Sep 07 2026

Valid 072000Z - 081200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
CENTRAL NORTH DAKOTA AND SOUTHEAST SOUTH DAKOTA...

...SUMMARY...
Widely scattered severe storms capable of mainly large hail are
expected over portions of North Dakota as well as southeast South
Dakota into northeast Nebraska this afternoon into evening. Isolated
damaging wind potential will exist over the northern and central
Plains into the upper Mississippi Valley. Locally damaging wind
gusts remain possible this afternoon over the central Gulf Coast
states.

...20Z Update...
The MRGL Risk/5-percent wind area was expanded slightly
west-southwestward in parts of eastern MT. Here, a small
north/south-oriented line segment is tracking eastward into an
increasingly warm PBL. This activity will continue to pose a risk of
a few severe wind gusts this afternoon. See MCD #2264 for more
details. Elsewhere, very minimal changes were made with this update.

..Weinman.. 09/07/2026

.PREV DISCUSSION... /ISSUED 1112 AM CDT Mon Sep 07 2026/

...ND...
A fast-moving shortwave trough currently over WY/MT will track
northeastward into the Dakotas this afternoon. Strong
heating/mixing in southwest ND will lead to a sharpening dryline
across central ND by mid/late afternoon. This will be the likely
focus for thunderstorm development after 22z. Forecast soundings in
the warm-sector east of the dryline suggest sufficient low-level and
deep-layer shear for supercell storm-modes. Large hail and perhaps a
tornado or two are possible in the most intense storms. This
activity will spread eastward into northeast ND this evening before
weakening.

...CO/KS/NE/SD...
A weak surface boundary is present today from northeast CO into
central NE. Scattered afternoon thunderstorms will form over the
mountains of central CO, with development spreading eastward along
the boundary through the afternoon. Strong heating and a deeply
mixed boundary-layer will promote intense downdrafts in the
strongest cores. By early evening, activity may spread into
southeast SD where greater low-level moisture and CAPE will pose a
risk of a few more intense storms capable of hail or even a tornado.
Recent model solutions have been backing off on this SD scenario,
but will maintain the ongoing SLGT for now.

...LA/MS/AL...
Hot and humid conditions will prevail over the central Gulf coast
region today, with full sunshine and dewpoints in the low-mid 70s.
Steering flow is weak, but high CAPE and ample moisture suggest a
risk of occasional intense downdrafts in the strongest storms.


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SPC Sep 7, 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
0744 AM CDT Mon Sep 07 2026

Valid 071300Z - 081200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
NORTH DAKOTA AND SOUTHEAST SOUTH DAKOTA INTO NORTHEAST NEBRASKA...

...SUMMARY...
Widely scattered severe storms capable of mainly large hail are
expected over portions of North Dakota as well as southeast South
Dakota into northeast Nebraska this afternoon into evening. A
broader area of isolated large hail and damaging wind potential
exists over the northern and central Plains into upper Mississippi
Valley. Locally damaging wind gusts appear possible over the central
Gulf Coast states Monday afternoon and evening.

...Northern/Central Plains into the Upper Mississippi Valley...
Early-morning satellite imagery depicts a deep upper trough over the
western CONUS. A trio of notable shortwave troughs are embedded
within this larger troughing, with the lead wave currently
progressing through eastern MT. Expectation is for this lead wave to
continue northeastward into the southern Canadian Prairie Provinces.
Surface low attendant to this lead shortwave is currently over
east-central MT. This low is also forecast to progress northeastward
just ahead of its parent shortwave for much of the day, before then
occluding over southern Saskatchewan this evening.

Showers and thunderstorms are currently ongoing from central MT into
western ND in the vicinity of this surface low, supported by a
combination of warm advection around the low and large-scale ascent
attendant to the shortwave trough. Warm-air advection is also
supporting additional thunderstorms from the NE Panhandle into
central SD. All of this activity is expected to gradually to shift
northeastward this morning in tandem with the progression of the
shortwave and its stronger low/mid-level southerly flow. Steep
mid-level lapse rates, MUCAPE of 1000-1500 J/kg, and 35-45 kt of
effective bulk shear could support occasional storm organization
with an associated risk for isolated large hail.

Renewed thunderstorm development is anticipated this afternoon in
several areas in the wake of the morning storms. One area is along a
dryline-like surface trough that is forecast to extend from the
occluding low over southern Saskatchewan to another low over western
SD. Strong low-level convergence is likely along this boundary, with
dewpoints remaining in the mid to upper 60s just east of the
boundary. Some convective inhibition may linger, and overall storm
coverage will likely remain isolated to widely scattered as a
result. However, any storms that develop should become supercells
capable of all severe hazards, including very large hail and a brief
tornado.

Another area is over portions of south-central and southeast SD into
northeast CO, from the vicinity of the secondary surface low of
western SD southwest along a pre-frontal trough. Some limited
convective inhibition may remain over this region as well, likely
keeping the overall storm coverage isolated to widely scattered.
Even so, kinematic profiles do support the potential for supercells
with any persistent deep convective, particularly over southeast SD.
Here, the proximity to the low-level jet results in considerable
veering through the lowest 1-2 km AGL, with effective SRH of 200-300
m2/s2 and effective bulk shear magnitudes of 40-45 kt. Primary
severe risk with any supercells is large to very large hail,
although the low-level veering will support some tornado risk as
well.

...Central Gulf Coast...
A hot and very moist air mass is forecast this afternoon ahead of a
weak front pushing into the region from the north with MLCAPE
increasing to 2500-3500 J/kg. Forcing for ascent and vertical shear
will remain weak; however, the degree of instability and high
moisture content will be supportive of intense pulse storms capable
of damaging wet microbursts from mid-afternoon into evening.

..Mosier/Lyons.. 09/07/2026


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SPC Sep 7, 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 Mon Sep 07 2026

Valid 071200Z - 081200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER NORTHWEST
INTO CENTRAL NORTH DAKOTA AND SOUTHEAST SOUTH DAKOTA INTO NORTHEAST
NEBRASKA...

...SUMMARY...
Widely scattered severe storms capable of mainly large hail are
expected over portions of northwest and central North Dakota and
southeast South Dakota into northeast Nebraska Monday afternoon into
evening. A tornado or two is possible in southeast South Dakota. A
broader area of isolated large hail and damaging wind potential
exists over the northern and central Plains into upper Mississippi
Valley. Locally damaging wind gusts appear possible over the central
Gulf Coast states Monday afternoon and evening.

...Synopsis...

A vigorous short-wave trough will pivot from the northern Rockies
through the northern High Plains with an associated strengthening of
the mid/upper-level wind field forecast across the northern Plains
into the upper MS Valley. A low-level jet (LLJ) will also be
sustained over the northern and central Plains into upper MS Valley
ahead of a surface cold front advancing through the northern Plains
and central High Plains.

...Northern and central Plains into the upper Mississippi Valley...

Clusters of mainly elevated thunderstorms may be ongoing at 12Z
Monday from eastern MT into the Dakotas within a zone of forcing for
ascent preceding a lead, mid-level disturbance and coincident with
the exit region of the LLJ. The presence of steep mid-level lapse
rates, MUCAPE of 1000-1500 J/kg, and 35-45 kt of effective bulk
shear will be supportive of some storm organization with an
associated risk for isolated large hail occurrences through the
morning hours as that convective regime shifts east across the
Dakotas.

On the periphery of more persistent cloudiness associated with the
morning storms, stronger insolation coupled with dewpoints in the
upper 60s to low 70s F and modestly steep mid-level lapse rates are
expected to yield a moderately unstable air mass by mid to late
afternoon with MLCAPE up to 1500-2500+ J/kg and a weakening cap.
Surface-based thunderstorm development will become increasingly
likely at that time, aided by increasing height falls attending the
primary short-wave trough.

The 00Z models indicate one potentially favored location for storm
development over portions of south-central and southeast SD into
northeast CO, from the vicinity of a secondary surface low southwest
along a pre-frontal trough. RAP-based hodographs over southeast SD
indicate considerable veering through the lowest 1-2 km AGL with
effective SRH of 200-300 m2/s2 and effective bulk shear magnitudes
of 40-45 kt, owing to the proximity of the LLJ. Accompanying
thermodynamic profiles suggest modest low-level lapse rates with
some residual capping. However, given surface-based storm initiation
and sustenance, supercells would be likely with an associated large
hail and tornado threat.

A hotter and more well-mixed boundary layer is expected with
southwestward extent ahead of the pre-frontal trough where
high-based storms capable of severe wind gusts and hail appear
possible.

Surface-based storms also appear possible ahead of an occluding
surface low and trailing cold front from northwest into central ND.
While the boundary layer may remain relatively cool from the
early-day storms, cooling mid-level temperatures will effectively
steepen lapse rates, yielding sufficient instability amidst 40-50 kt
of deep-layer layer. As such, supercells appear possible with an
attendant risk for large hail.

...Central Gulf Coast...

A hot and very moist air mass is forecast Monday afternoon ahead of
a weak front pushing into the region from the north with MLCAPE
increasing to 2500-3500 J/kg. Forcing for ascent will remain weak as
will vertical shear; however, the degree of instability and high
moisture content will be supportive of intense pulse storms capable
of damaging wet microbursts from mid-afternoon into evening.

..Mead/Chalmers.. 09/07/2026


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SPC Sep 7, 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
0740 PM CDT Sun Sep 06 2026

Valid 070100Z - 071200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
WESTERN AND CENTRAL MONTANA AND OVER A SMALL PART OF THE LOWER
MISSOURI VALLEY...

...SUMMARY...
Widely scattered large hail occurrences with hailstones up to two
inches are expected over portions of western and central Montana
this evening into tonight. More sporadic occurrences of large hail
and severe wind gusts appear possible over the northern and central
High Plains, and across parts of the lower Missouri Valley.

...Northern Rockies into the northern Plains...

Separate vorticity lobes and associated wind maxima will progress
into the northern Rockies and northern High Plains tonight with a
resultant zone of height falls/forcing for ascent overspreading the
region. In the lower levels, a surface cyclone will be maintained
over southeast MT while a nocturnal jet develops over the northern
and central High Plains.

Thunderstorms currently intensifying over western MT are expected to
increase in coverage and intensity while spreading into
north-central MT ahead of the western vorticity lobe rounding the
base of the Pacific Northwest upper low. While the boundary layer is
somewhat cool/stable, the presence of steep mid-level lapse rates,
MUCAPE up to 1000-1500 J/kg, and 40-45 kt of effective bulk shear
will be supportive of supercells with the primary hazard being large
hail up to two inches.

Farther east, isolated to widely scattered storms have developed
along and ahead of a lee trough and the MT surface low from western
ND into northeast CO within a steep lapse rate and moderately
unstable environment (see the 00Z UNR and LBF soundings). Veering
winds with height with up to 35-40 kt of deep-layer shear are
sufficient to support an observed supercell storm mode with the
primary hazards being large hail potentially in excess of two inches
and locally severe wind gusts. A tornado was recently reported with
a slow-moving supercell over McKenzie County, ND. However, sizable
temperature-dewpoint spreads within the inflow air mass, and the
tendency for increasing convective inhibition in the coming hours
are likely to limit a continuing tornado threat despite increasing
low-level shear.

Storm coverage is expected to remain limited through the remainder
of the evening with a potential increase later tonight with the
arrival of the eastern vorticity lobe and strengthening low-level
jet. As such, the threat for sporadic large hail and severe wind
gust occurrences may linger into the overnight hours from eastern MT
into the western parts of the Dakotas and NE.

For additional information, see recently issued mesoscale discussion
#2259.

...Lower Missouri Valley...

Widely scattered strong to severe storms are ongoing this evening
over parts of southeast NE, northeast KS, and northwest MO with
activity focused along outflow boundaries and a synoptic front in
the area. The inflow air mass remains hot and relatively moist as of
00Z with observed soundings indicating steep low-level lapse rates
with MLCAPE up to 1500-3000 J/kg. The 00Z TOP sounding sampled
around 30 kt of deep-layer shear, which will remain supportive of
episodic supercell structures for the next couple of hours with an
associated risk for large hail and locally damaging wind gusts.

For additional information, see recently issued mesoscale discussion
#2258.

..Mead.. 09/07/2026


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