SPC AC 121236
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0736 AM CDT Wed Aug 12 2026
Valid 121300Z - 131200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE
NORTHERN/CENTRAL PLAINS TO THE LOWER OHIO VALLEY...
...SUMMARY...
Scattered severe thunderstorms are possible today through this
evening from parts of the mid Mississippi Valley and lower Ohio
Valley into portions of the central and northern High Plains.
Severe gusts and large hail are the primary hazards.
...IA to OH Valley...
Radar/satellite imagery this morning show several thunderstorm
clusters ongoing from IA into the OH Valley. The most notable
thunderstorm cluster is over far eastern IA and is moving into
central and northern IL this morning. The airmass downstream of
this activity is very moist and extremely unstable [reference the 12
UTC Davenport, IA raob (4300 J/kg MLCAPE)], and it is located near
the terminus of a 35-kt west-southwesterly LLJ over northern MO.
Expecting a gradual intensification of storms this morning across IL
with a risk for scattered severe gusts and associated wind damage.
Considerable uncertainty remains regarding the eventual evolution of
additional storm clusters over parts of the Midwest through this
afternoon. Outflow from morning showers/storms over eastern IN into
central KY will likely inhibit appreciable severe risk farther east
across parts of the OH Valley. Nonetheless, a moist and
destabilizing boundary layer will lend a risk for scattered wind
damage and isolated large hail with the stronger storms through the
late afternoon and evening.
...Northern/Central Plains...
East/southeasterly low-level flow will maintain modest moisture
across the Dakotas, increasing with southward extent across NE into
northern KS. Near-60 F dewpoints will likely spread westward into
eastern CO/WY/MT beneath steep lapse rates. Ample heating will
result in moderate buoyancy and 30+ kt effective shear---supporting
some organization to the scattered thunderstorms forecast to develop
later this afternoon/evening. Initial cells will pose a threat for
large hail and severe gusts. Some clustering may occur during the
evening but confidence remains low regarding specific corridors
where the severe threat will focus.
...Lower MI into NY/PA/NJ...
A belt of stronger northwesterly flow aloft will extend from Lower
MI into NY/PA today. A seasonally moist/unstable airmass will be in
place. Vertically veering wind profiles will foster 35+ kt
effective shear magnitudes, while hodographs are fairly elongated.
Midlevel lapse rates will remain modest, with MLCAPE around
1000-1500 J/kg expected. Isolated to widely scattered storms will
pose a risk for damaging gusts and marginally severe hail.
...TN Valley/Southeast...
Thunderstorms are expected to develop by midday within a very moist
and strongly unstable airmass. Deep-layer northwesterly flow will
remain weak, but steepened 0-2 km lapse rates and high PW (near 2
inches) will support an isolated risk for some stronger water-loaded
downdrafts capable of wind damage.
...Lower CO River Valley...
Model guidance shows widely scattered storms developing this
afternoon near a weak upper trough analyzed this morning via
water-vapor imagery. Some of the stronger thunderstorm downdrafts
may be capable of isolated severe gusts.
..Smith/Kerr.. 08/12/2026
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
SPC AC 120600
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Wed Aug 12 2026
Valid 131200Z - 141200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE COLORADO
FRONT RANGE AND CENTRAL HIGH PLAINS EASTWARD INTO PARTS OF THE
MIDWEST AND OHIO VALLEY...
...SUMMARY...
Isolated severe storms are possible on Thursday from the Colorado
Front Range and central High Plains into the Ohio Valley.
...Synopsis...
Some amplification of the upper-level pattern is expected on
Thursday across the central/eastern CONUS. An upper ridge initially
over the lower MS Valley is forecast to expand and build northward
into parts of the Great Plains. To the east of building ridge, a
seasonably strong mid/upper-level shortwave trough is forecast to
move southeastward across the Great Lakes towards the Northeast. A
surface low is forecast to remain in place across the south-central
Plains. A nearly stationary front is forecast to extend
east-northeast of the low toward the lower MO Valley, and then
east-southeastward toward the lower OH Valley.
...Central Plains into parts of the Midwest/Ohio Valley...
Isolated severe potential remains evident in the vicinity of the
surface front on Thursday, though confidence in the details remains
low. Elevated convection and possibly a remnant MCS may be ongoing
at the start of the period from eastern NE into parts of IA/northern
MO. Depending on the extent to which the early-day convection can
propagate within the rich moisture and moderate to strong buoyancy
along the frontal zone, some severe threat could spread
east-southeastward toward the lower OH Valley through the day.
Otherwise, isolated storms may develop near/north of the front
through the day, with an increase in coverage expected Thursday
evening within a warm-advection regime. Generally modest and
front-parallel mid/upper-level flow may lead to training storms and
a tendency for convection to be undercut or generally remain
somewhat elevated. However, deep-layer shear will still be modestly
supportive of organized convection within the moist and unstable
environment, with some potential for isolated damaging gusts and
hail.
...CO Front Range into the adjacent High Plains...
To the north/northwest of the primary surface low, moist easterly
low-level flow will support moderate to locally strong
destabilization from the CO Front Range into parts of the central
High Plains. Deep-layer flow will generally remain modest, but
veering wind profiles will provide sufficient effective shear for
some storm organization. Isolated hail and locally severe gusts will
be possible with the strongest storms in this region.
Isolated to widely scattered storms will also be possible within the
hot and well-mixed regime near/south of the front and surface low.
Weak deep-layer shear should limit storm organization in this
regime, but steep low-level lapse rates could support localized
severe gusts.
...Northeast...
Seasonably strong mid/upper-level flow will overspread the Northeast
on Thursday. However, low-level flow will remain rather weak, and
generally modest moisture and lapse rates will limit
destabilization. MLCAPE Of 500-1000 J/kg will support development of
widely scattered thunderstorms across northern New England. There
will be some displacement between the strongest deep-layer flow and
more favorable buoyancy. Small hail and gusty winds could accompany
the strongest storms, but confidence in sufficient destabilization
remains too low for severe probabilities at this time.
...Southeast...
Thunderstorm development is expected across parts of AL/GA/SC on
Thursday, within a very warm and moist environment. Guidance varies
regarding the extent to which early-day convection and related
outflow move into the region from the north, and the influence any
such convection/outflow would have on storm development and
evolution later in the day. In general, deep-layer flow/shear will
be weak, but the very warm and moist environment could support
localized downburst potential. Confidence in an organized severe
threat is currently low, but if trends support the presence of any
outflow boundaries or remnant MCVs emanating from upstream, then
wind probabilities may eventually be needed for some part of this
region.
...Great Basin...
Storm development is again expected across parts of the Great Basin
on Thursday afternoon, with coverage potentially aided by a midlevel
trough approaching the region from central/southern CA. Deep-layer
shear will remain modest at best, but favorable lapse rates and
cooling temperatures aloft could support relatively vigorous
updrafts with potential for localized strong to severe gusts.
Uncertainty remains regarding the organization of any severe threat,
but wind probabilities may eventually be needed for this area as
well.
..Dean.. 08/12/2026
WUUS02 PTSDY2
SPC AC 120737
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0237 AM CDT Wed Aug 12 2026
Valid 141200Z - 151200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CO
FRONT RANGE AND CENTRAL HIGH PLAINS EASTWARD INTO THE MIDWEST AND
OHIO VALLEY...
...SUMMARY...
Isolated strong to severe storms are possible from the central High
Plains into parts of the Midwest.
...Synopsis...
A broad upper trough will remain in place across the West on Friday,
while an upper ridge will continue to gradually build from the lower
MS Valley into the Midwest. A seasonably deep mid/upper trough will
remain in place over the Northeast. A broad surface low is expected
to remain in place over the south-central High Plains. A frontal
zone that initially extends generally eastward from the low toward
the Midwest and Ohio Valley may tend to lift northward by later in
the period, though its position will continue to be influenced by
antecedent and ongoing convection.
...Midwest/Ohio Valley...
Storms may be ongoing Friday morning across parts of the Midwest.
This convection will likely be elevated to the north of the frontal
zone, but moderate to strong MUCAPE and sufficient deep-layer shear
could support an isolated severe threat with the strongest early-day
storms.
Evolution of the front and additional storm development later in the
day remains quite uncertain. The environment may remain capped along
and to the warm side of the front, but additional elevated
convection may develop during the evening, within a modest
warm-advection regime. While deep-layer shear and lapse rates will
likely be weaker compared to previous days, substantial buoyancy
near/north of the frontal zone could still support potential for
isolated hail and damaging winds.
...CO Front Range into the High Plains...
Similar to D2/Thursday, moist low-level easterly flow to the north
of the surface low and front will support moderate destabilization
across parts of the CO Front Range and adjacent High Plains. Modest
lapse rates and only marginally favorable deep-layer shear should
limit a more organized threat, but cells capable of isolated hail
and localized severe gusts will be possible by late afternoon, with
some modest outflow-driven clustering possible. Farther south,
high-based convection may develop across the south-central High
Plains and pose localized downburst potential.
...Carolinas/VA...
Modest midlevel northwesterly flow will overspread parts of the
Carolinas and Virginia on Friday, though guidance varies
considerably regarding the magnitude of diurnal destabilization
across this region. Somewhat organized wind-damage potential could
evolve if sufficient destabilization occurs, but confidence is too
low for probabilities at this time.
..Dean.. 08/12/2026
WUUS03 PTSDY3
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 1930Z
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