SPC Aug 13, 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
0758 PM CDT Wed Aug 12 2026

Valid 130100Z - 131200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS INTO WESTERN IOWA...

...SUMMARY...
Multiple supercells with large hail potential across the
northern/central High Plains should evolve into a bowing cluster
tonight while spreading eastward across Nebraska and eventually into
Iowa by early Thursday morning. This cluster will be capable of
producing scattered severe/damaging winds.

...Northern/Central Plains into Iowa...
A mix of clusters and supercells is ongoing this evening from far
northeast CO into western NE. The environment downstream into
central/eastern NE remains favorable to maintain severe convection
along/near a surface front. Large hail will remain possible with any
sustained supercells given 35-45+ kt of deep-layer shear, and
eventual upscale growth into a bowing cluster appears probable
tonight with modestly enhanced east-southeasterly low-level flow
providing an influx of warm/moist air. If this occurs, then the
threat for severe/damaging winds would increase across
central/eastern NE and perhaps eventually western IA, with isolated
gusts of 75+ mph possible. Severe probabilities have been adjusted
based on latest observational and short-term guidance trends.
Reference Mesoscale Discussion 1961 for more details regarding the
near-term severe threat across northeast CO/western NE.

...Mid Mississippi Valley into the Lower Ohio Valley...
Ongoing thunderstorm clusters across parts of the mid MS and lower
OH Valleys have mostly diminished in intensity as they have become
generally displaced south of the stronger mid-level flow across the
Midwest/Great Lakes. Even with the gradual weakening trend observed,
a couple of stronger clusters persist. Isolated damaging winds will
remain possible for a couple more hours this evening as this
activity spreads slowly southward.

...Northeast...
Loosely organized cells may continue to pose an isolated hail/gusty
wind threat for the next hour or two across southern NY and vicinity
along/near a surface front. The loss of daytime heating and gradual
decrease in instability should result in eventual weakening of
ongoing convection.

...Lower Colorado River Valley...
High-based thunderstorms which developed this afternoon in a hot and
well-mixed boundary layer across interior southern CA and western AZ
may remain capable of producing occasional severe gusts for a couple
more hours this evening.

..Gleason.. 08/13/2026


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TTzw5k

SPC Aug 12, 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
1130 AM CDT Wed Aug 12 2026

Valid 121630Z - 131200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM ILLINOIS TO
KENTUCKY AND FROM THE NORTHERN HIGH PLAINS TO THE MID MISSOURI
VALLEY...

...SUMMARY...
Scattered severe thunderstorms with occasional wind damage are
possible this afternoon/evening from Illinois/Indiana into Kentucky.
Initial supercells with very large hail will be possible this
afternoon/evening across the central/northern High Plains. The
storms are expected to evolve into a cluster or two overnight while
spreading eastward across Nebraska/South Dakota with the potential
for severe outflow gusts.

...OH Valley area through this evening...
An MCS is ongoing across northern IL with the primary cold pool
surge and bowing segment progressing from northeast IL into
northwest IN. Elevated convection is ongoing in the zone of warm
advection atop the cold pool in IN. This elevated convection will
pose a threat for isolated large hail into this afternoon, while a
feed of steeper midlevel lapse rates and low-level moisture from the
west will help maintain the IL/IN MCS into this afternoon with a
continued threat for occasional wind damage with gusts of 60-75 mph.
The eastern extent of the severe threat into OH is uncertain given
the ongoing/elevated convection and limited recovery time. Thus,
the eastward extent of any wind threat associated with the ongoing
IL/IN MCS is likewise uncertain. Additional thunderstorm
development is possible this afternoon along the trailing outflow
from central IL into southern IN and KY, where occasional wind
damage will be possible into this evening.

...Northern Plains this afternoon through tonight...
A subtle midlevel speed max over southwest WY will progress eastward
around the northwest periphery of the southern Plains ridge. Weak
ascent preceding this wave, in combination with surface heating in
cloud breaks and low-level upslope flow with boundary-layer
dewpoints in the 60s, will support scattered afternoon/evening
thunderstorm development from northeast CO into western SD.
Lingering steep midlevel lapse rates on the fringe of the monsoonal
moisture plume in WY and effective bulk shear near or above 40 kt
(with long hodographs aloft) will favor supercells initially with
the potential for very large hail (2-3 inches in diameter). There
will likely be some upscale growth into a cluster or two this
evening into tonight on the nose of a 30-40 kt low-level jet across
NE/SD, with a transition to severe outflow gusts of 65-80 mph as the
main threat. The storm cluster(s) will likely reach western IA
early Thursday morning.

...Lower MI into western NY/PA through late evening...
Subtle speed maxima will move east-southeastward from Lower MI to
NY/PA through this evening. Midlevel lapse rates of 6-7 C/km and
boundary-layer dewpoints in the mid 60s will support MLCAPE near or
above 1000 J/kg, in an environment with sufficient deep-layer
shear/hodograph length for storms with supercell structures.
Isolated large hail and wind damage will be the main threats, though
a more discrete mode would be less favorable for wind damage, and
storm coverage could remain somewhat isolated. Thus, will maintain
a MRGL risk, though there was some consideration for an upgrade to
SLGT across western NY and vicinity.

...South GA/north FL this afternoon...
Scattered thunderstorm development appears probable from south GA
into north FL this afternoon along a subtle confluence zone with
large buoyancy immediately southwest of a remnant MCV over southeast
GA. A few multicell clusters will be capable of producing isolated
strong outflow gusts/wind damage with downbursts.

..Thompson/Chalmers.. 08/12/2026


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TTzmTm

SPC Aug 12, 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
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


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TTzVRR

SPC Aug 12, 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
1214 AM CDT Wed Aug 12 2026

Valid 121200Z - 131200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE
NORTHERN/CENTRAL PLAINS TO THE LOWER OHIO VALLEY...

...SUMMARY...
Thunderstorms with severe gusts and hail will be possible this
afternoon and evening across parts of the central and northern High
Plains. Damaging gusts and isolated hail will also be possible
across parts of the Midwest and Ohio Valley.

...IA to OH Valley...

One or more MCSs migrating through enhanced northwesterly flow aloft
amid a very moist and unstable airmass is possible again today
across the Midwest toward TN. Most forecast guidance suggests an MCS
or thunderstorm clusters could be ongoing over IA at the start of
the period (12z), with warm advection storms arcing across parts of
IL/IN. The early day warm advection storms could develop southeast
across the OH Valley, while the IA MCS develop southeast across the
Mid-MS/Lower OH Valley through afternoon. The exact evolution of
convection that is not yet apparent is uncertain, and how outflow
may influence how this activity evolves through the afternoon.
Regardless, the overall environmental parameter space will be
favorable for a damaging wind and isolated hail risk through early
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. Modest moisture beneath steep midlevel lapse rates
and 30+ kt effective shear magnitudes will support scattered
thunderstorm development across the High Plains. Initial cells will
pose a large hail and damaging wind risk. It is unclear how
convection will evolve with eastward extent across the region as
outflow from prior convection may largely limit stronger
destabilization. A developing low-level jet during the nighttime
hours will be focused across the southern Plains toward KS/southern
NE. This could support some upscale growth potential, but confidence
is low.

...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 small 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 steep low-level lapse rates and PW values near 2
inches could support isolated wet microbursts with stronger
multi-cell clusters.

..Leitman/Moore.. 08/12/2026


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TTzCPd