SPC Aug 22, 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
0101 AM CDT Sat Aug 22 2026

Valid 221200Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE UPPER OHIO VALLEY...

...SUMMARY...
Scattered damaging gusts are likely across the Ohio Valley with more
isolated damaging wind potential extending westward into the Mid
Mississippi Valley and southern Plains this afternoon/evening.
Isolated hail and damaging winds are also possible over the Front
Range, Great Basin and parts of the northern Rockies.

...OH and TN Valleys...
An upper low initially over the western Great Lakes is forecast to
deepen as it moves southeastward today and tonight. A belt of
stronger mid-level flow behind the trough will move into parts of
the Plains and Midwest. A weak surface low and trailing cold front
will move southeastward across the Lakes and into the upper OH
Valley through the day. Ahead of the front, upper 60s to 70s F
surface dewpoints and filtered diurnal heating should allow for
moderate destabilization, sufficient for scattered to numerous
thunderstorms by early afternoon. Despite generally modest to weak
deep-layer shear, steepening of lower/mid-level lapse will support
stronger downdrafts within organized multicell clusters. With time,
some upscale growth into linear segments is also possible and would
also favor a risk for scattered damaging gusts. This appears most
likely across central/eastern OH and KY into western PA/WV.

Farther south, more isolated storm coverage is expected ahead of the
front from the western Carolina Piedmont to the TN Valley. Steep
low-level lapse rates and enhanced low and mid-level northwesterly
flow will still support some risk for isolated damaging gusts.

...Ozarks/Mid MS Valley...
A weak convectively augmented shortwave trough is forecast to move
from southeastern KS and southern MO into northern AR along western
portions of a weak surface front by midday. Ahead of these features,
a very warm and humid air mass will be in place, which should allow
substantial diurnal destabilization and eventual thunderstorm
development. Enhanced northwesterly flow may help organize a few
thunderstorm clusters as they spread eastward from the Ozarks into
the ArkLaTex and mid MS Valley. Damaging wind gusts and some hail
are possible.

...Front Range and adjacent High Plains...
Post-frontal upslope flow, aided by a weak short wave impulse on the
eastern periphery of the upper ridge will support thunderstorm
development along/east of the Laramie mountains through Colorado
Front Range this afternoon. On the fringes of the stronger northwest
flow aloft, deep-layer shear will be marginal for storm
organization. Steep mid-level lapse rates and moderate buoyancy
could support some hail with the stronger updrafts. Isolated
damaging gusts are also possible, especially with any more
persistent thunderstorm clusters.

...Southern Plains...
Very hot surface temperatures (100+ F) are likely across parts of
western North TX into southwestern and central OK this afternoon.
Low-level convergence near a thermally enhanced surface low and weak
front will aid high-based thunderstorm development late afternoon
into the early evening. Weak buoyancy atop the steep low-level lapse
rates and deep mixed layer will favor very strong downdrafts within
the high-based storms. Isolated severe gusts (possibly 65-75 mph
gusts) associated with microbursts are possible as convection is
forecast to move southward through the evening.

...Northern Rockies to the Great Basin....
An upper low along the western periphery of the substantial
mid-level ridge over the Southwest will migrate northward toward the
international border as a belt of stronger mid-level flow
overspreads a plume of monsoon moisture from the Great Basin to the
Northern Rockies. Ascent from the upper wave and heating of the
modestly moist air mass should allow for weak destabilization and
scattered thunderstorm development. Steep lapse rates could support
isolated severe gusts.

Isolated hail is also possible with scattered thunderstorms from
eastern WA into the ID panhandle. Closer to the upper trough and
beneath strong mid-level flow, elongated hodographs may promote
organization with transient supercell structures. Cooler mid-level
temperatures could favor hail production despite modest overall
moisture.

..Lyons/Weinman.. 08/22/2026


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SPC Aug 21, 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 Fri Aug 21 2026

Valid 212000Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS...MIDWEST...LOWER MS VALLEY...AND CAROLINAS...

...SUMMARY...
Scattered severe thunderstorms capable of producing large hail (some
2+ inches) and severe winds may occur over parts of the central
Plains into the Midwest this afternoon and evening. Damaging winds
also remain possible with scattered to numerous thunderstorms across
portions of the Carolinas and northern Gulf Coast states.

...20z Update...

...Lower MS Valley and Carolinas...
The forecast generally remains on track with only a minor eastward
expansion of the 15% wind probabilities in southern Alabama and the
far western Florida Panhandle. Modestly stronger low-to-mid level
flow (evident in the MOB VWP) and favorable thermodynamic profiles
(steep low-level lapse rates and high PW) should support stronger
downbursts and scattered damaging wind gusts, similar to areas
farther east. See Mesoscale Discussion #2069 for additional
short-term details.

...Midwest...
The Level 1/Marginal risk and Level 2/Slight risk areas were
expanded slightly northwestward based on observed convective
development ongoing across as of 1945 UTC across southwestern
Wisconsin. Some consideration was given to adding a targeted 5%
tornado probability area along the remnant outflow boundary
extending from southeast of Rockford, IL, into southwestern
Wisconsin; however, uncertainty regarding the longevity of a
supercellular storm mode (owing to the potential for cell
mergers/interactions) and the presence of only modest low-level
hodograph curvature/SRH precludes a 5% area at this time. See
Mesoscale Discussion #2070 for additional short-term details.

...Central Plains...
Latest high-res guidance has poorly captured the evolution of
morning and ongoing convection across portions of central and
eastern Nebraska through early this afternoon, which lends
uncertainty to the evolution of the severe threat through the rest
of the period. Given the continued potential for ongoing convection
to intensify and/or for additional redevelopment through the
evening, however, severe probabilities have been maintained with
only minor expansions made to the CIG1 wind and hail areas.

...Northern Great Basin into the Snake Valley...
Convective development is ongoing across portions of central/eastern
Nevada, with thunderstorms forecast to evolve northward through the
afternoon. The 5% wind probabilities and CIG1 area were expanded
westward and northward based on the placement of ongoing
thunderstorm activity and the latest HRRR/RRFS runs.

..Chalmers/Moore.. 08/21/2026

.PREV DISCUSSION... /ISSUED 1124 AM CDT Fri Aug 21 2026/

...Central Plains into the Midwest...
A northwest flow regime will result in a weakly forced and in a
limited confidence severe setup across the central Plains. Ongoing
widely scattered storm activity may persist and reinvigorate during
the afternoon, or new development occurs along residual outflow as
the airmass becomes moderately to strongly unstable. Forecast
sounding profiles show moist low levels beneath steep 700-500 mb
lapse rates amid veering and strengthening flow with height. Large
hail (some 2+ inches) would be a threat with any sustained
supercells along with severe gusts (60-75 mph). If a small cluster
can eventually develop, the severe-wind hazard would likely focus
with these potential storms.

A small west to east oriented band of storms is moving south across
southern WI to the east of a weak surface low and immediately
downstream of an associated mid-level perturbation. While effective
bulk shear is forecast to remain fairly modest (around 20-30 kt), a
mix of multicells and marginal supercells is expected to develop
later this afternoon across parts of southern WI into
northern/central IL along and ahead of a weak front. Severe hail
may occur with any persistent cells, while the threat for damaging
winds should increase as small clusters form and spread
east-southeastward through the early evening. While low-level
flow is not forecast to become overly strong, sufficient veering
with height through low/mid levels should exist to support modest
low-level hodograph curvature and some risk for a brief tornado.

...Carolinas...
Weakened shower/thunderstorm activity associated with an MCV over
the western Carolinas will likely dissipate during the early
afternoon. However, renewed storm development is forecast in
proximity to this upper disturbance, as well as near residual
outflow from the earlier convection and a surface cool front draped
from the GA/SC Piedmont northeastward into the coastal plain of
eastern NC. Strong heating of a seasonably moist boundary layer
will result in strong instability by mid afternoon. Sufficient
deep-layer shear for some organized multicell potential will be
greatest near the upper-level feature. Farther southeast near the
SC Low Country, weaker flow will result in a pulse thunderstorm
mode. Scattered damaging gusts are possible with the stronger
thunderstorms through the early evening before nocturnal stability
weakens storms and ends the severe threat.

...North TX east into northern Gulf Coast states...
Antecedent outflow from overnight storm clusters over the lower MS
Valley and AL will serve as a focus for storm development this
afternoon. Farther west, a more pronounced decaying MCS and
associated southward-moving MCV over east-central OK will also focus
storm activity across east TX into western LA. The 12 UTC Little
Rock raob showed a belt of enhanced flow around the 4-5 km layer
(35-40 kt). Other than a localized corridor where moderate
northerly flow will overspread a strongly destabilizing boundary
layer, slightly weaker northerly to northeasterly flow will
encompass this larger region from north TX to Mobile Bay.
Nonetheless, the development of very steep 0-3 km lapse rates (9 deg
C/km) by early to mid afternoon and high PW (1.75-2.0 inches) will
support scattered wind damage with the more intense downdrafts (most
likely and concentrated from east TX through southern MS).

...Northern Great Basin into the Snake Valley...
A mid-level vorticity max rotating northward around the western
periphery of the Four Corners upper high, will move into northern
NV/UT by late afternoon. Deep inverted-V profiles will develop by
mid afternoon with a dry sub-cloud layer featuring large surface
temperature-dewpoint spreads. A linear cluster of storms is
expected to evolve and move north across the NV/UT/ID vicinity
during the late afternoon and early evening. Evaporatively cooled
downdrafts will be potentially capable of severe gusts 60-75 mph.


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SPC Aug 21, 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
1124 AM CDT Fri Aug 21 2026

Valid 211630Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS...MIDWEST...LOWER MS VALLEY...AND CAROLINAS...

...SUMMARY...
Scattered severe thunderstorms capable of producing large hail (some
2+ inches) and severe winds may occur over parts of the central
Plains into the Midwest this afternoon and evening. Damaging winds
will also be possible with scattered to numerous thunderstorms
across portions of the Carolinas and northern Gulf Coast states.

...Central Plains into the Midwest...
A northwest flow regime will result in a weakly forced and in a
limited confidence severe setup across the central Plains. Ongoing
widely scattered storm activity may persist and reinvigorate during
the afternoon, or new development occurs along residual outflow as
the airmass becomes moderately to strongly unstable. Forecast
sounding profiles show moist low levels beneath steep 700-500 mb
lapse rates amid veering and strengthening flow with height. Large
hail (some 2+ inches) would be a threat with any sustained
supercells along with severe gusts (60-75 mph). If a small cluster
can eventually develop, the severe-wind hazard would likely focus
with these potential storms.

A small west to east oriented band of storms is moving south across
southern WI to the east of a weak surface low and immediately
downstream of an associated mid-level perturbation. While effective
bulk shear is forecast to remain fairly modest (around 20-30 kt), a
mix of multicells and marginal supercells is expected to develop
later this afternoon across parts of southern WI into
northern/central IL along and ahead of a weak front. Severe hail
may occur with any persistent cells, while the threat for damaging
winds should increase as small clusters form and spread
east-southeastward through the early evening. While low-level
flow is not forecast to become overly strong, sufficient veering
with height through low/mid levels should exist to support modest
low-level hodograph curvature and some risk for a brief tornado.

...Carolinas...
Weakened shower/thunderstorm activity associated with an MCV over
the western Carolinas will likely dissipate during the early
afternoon. However, renewed storm development is forecast in
proximity to this upper disturbance, as well as near residual
outflow from the earlier convection and a surface cool front draped
from the GA/SC Piedmont northeastward into the coastal plain of
eastern NC. Strong heating of a seasonably moist boundary layer
will result in strong instability by mid afternoon. Sufficient
deep-layer shear for some organized multicell potential will be
greatest near the upper-level feature. Farther southeast near the
SC Low Country, weaker flow will result in a pulse thunderstorm
mode. Scattered damaging gusts are possible with the stronger
thunderstorms through the early evening before nocturnal stability
weakens storms and ends the severe threat.

...North TX east into northern Gulf Coast states...
Antecedent outflow from overnight storm clusters over the lower MS
Valley and AL will serve as a focus for storm development this
afternoon. Farther west, a more pronounced decaying MCS and
associated southward-moving MCV over east-central OK will also focus
storm activity across east TX into western LA. The 12 UTC Little
Rock raob showed a belt of enhanced flow around the 4-5 km layer
(35-40 kt). Other than a localized corridor where moderate
northerly flow will overspread a strongly destabilizing boundary
layer, slightly weaker northerly to northeasterly flow will
encompass this larger region from north TX to Mobile Bay.
Nonetheless, the development of very steep 0-3 km lapse rates (9 deg
C/km) by early to mid afternoon and high PW (1.75-2.0 inches) will
support scattered wind damage with the more intense downdrafts (most
likely and concentrated from east TX through southern MS).

...Northern Great Basin into the Snake Valley...
A mid-level vorticity max rotating northward around the western
periphery of the Four Corners upper high, will move into northern
NV/UT by late afternoon. Deep inverted-V profiles will develop by
mid afternoon with a dry sub-cloud layer featuring large surface
temperature-dewpoint spreads. A linear cluster of storms is
expected to evolve and move north across the NV/UT/ID vicinity
during the late afternoon and early evening. Evaporatively cooled
downdrafts will be potentially capable of severe gusts 60-75 mph.

..Smith/Chalmers.. 08/21/2026


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SPC Aug 21, 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
1256 AM CDT Fri Aug 21 2026

Valid 211200Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE CENTRAL PLAINS...THE MIDWEST AND THE CAROLINAS...

...SUMMARY...
Scattered damaging hail (some greater than 2 inch diameter) and
severe wind gusts may occur over parts of the central Plains this
afternoon and evening. Scattered storms, some with severe wind gusts
and hail, also are possible across parts of the Midwest. Scattered
to numerous storms with damaging wind guts are possible over the
Carolinas and Southeast.

...Central Plains...
Mid-level ridging over the western US is forecast to intensify,
strengthening northwesterly flow aloft over much of the central US.
Several embedded disturbances will pass overhead with the enhanced
northwesterlies through the day. A surface low will move
southeastward through the Great Lakes as a weak trailing cold front
moves southward through the central Plains and Midwest.

Ahead of the front, a plume of steep mid-level lapse rates will
shift eastward across the central Plains toward the Mid-MO Valley
atop a corridor of rich low-level moisture. Diurnal destabilization
should result in 3000-4000 J/kg of MLCAPE from SD to NE. Isolated to
widely scattered thunderstorm development is expected from the Black
Hills southeastward along the cold front. Elongated/straight
hodographs and 45+ kt effective shear will favor initial supercells.
Large to very large hail (some greater than 2 inches diameter) will
be possible. With time, a forward propagating cluster or two may
develop and move southeast across parts of NE and KS with the
potential for severe gusts (a few near 70-80 mph). It is unclear
exactly how far southeast any storms will persist overnight, but any
more substantial clustering could allow at least an isolated severe
threat to continue into early Saturday.

A much drier and hotter environment over the High Plains to the west
could also support isolated to widely scattered high-based storms
from eastern CO into western KS. Very steep lapse rates in the
lowest 2-3 km with modest buoyancy aloft could allow a few severe
gusts.

...Midwest...
Beneath the upper trough over the western Great Lakes, cool
mid-level temperatures and robust surface moisture should result in
moderate destabilization from WI into eastern IA and northwest IL.
Scattered thunderstorms by mid afternoon ahead of the cold front
spreading southeastward. Enhanced northwesterly flow with deep-layer
shear of 30-40 kt will promote a mix of organized clusters and
supercells. The large buoyancy will support a risk for damaging
gusts and some hail.

...Southeast and Gulf Coast...
A broad upper trough will move across the central US into parts of
the southern Appalachians while a weak cold front moves southward
from the mid Atlantic today and tonight. Weak ascent from the upper
trough and near the front should focus diurnal thunderstorm activity
across the Carolians and southern Appalachians. Warm surface
temperatures and plentiful boundary-layer moisture will support
large buoyancy (3000+ J/kg MLCAPE) through the afternoon and evening
despite modest mid-level lapse rates. With scattered to numerous
storms expected, a few organized clusters may emerge with a risk
primarily for damaging wind gusts. Slight enhancement of the
westerly flow aloft could also support some isolated hail with the
stronger updrafts.

Farther south and west, a very humid and warm air mass is forecast
to become strongly unstable by early afternoon across the lower MS
Valley and Gulf Coast. Scattered to numerous thunderstorms are
expected along prior outflows and a weak, southward moving cold
front from East TX into LA/MS. The very strong buoyancy and high
PWAT content will support clustering and strong downdrafts with
sporadic damaging gust potential. Otherwise, weak vertical shear
will limit overall organization.

..Lyons/Weinman.. 08/21/2026


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