SPC Aug 10, 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
1225 AM CDT Mon Aug 10 2026

Valid 101200Z - 111200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTION OF
THE MIDWEST INTO PA AND NORTHERN MD/VA...AND ACROSS PARTS OF THE
NORTHERN PLAINS...

...SUMMARY...
Thunderstorms with severe wind gusts will be possible this afternoon
and evening from northern Illinois eastward into Pennsylvania.
Severe gusts and hail will also be possible from parts of the
central and northern Plains into the Midwest, with scattered strong
storms over southern Arizona.

...Synopsis...

A belt of enhanced west/northwesterly flow aloft will overspread the
northern Plains to the Midwest and southern New England
today/tonight. Only modest height falls are forecast at best.
However, several convectively enhanced vorticity maxima are forecast
to migrate through this upper flow regime, focusing several areas of
severe storm potential today into tonight from the northern Plains
to the upper Ohio Valley and parts of the Mid-Atlantic.

...IL to the Mid-Atlantic...

Early day thunderstorms may move across parts of the Midwest this
morning, but should generally be sub-severe. By midday, convection
could intensify within a couple of corridors. The first being the
upper Ohio Valley/PA/western NY. Thunderstorm clusters will pose a
risk for damaging winds and hail within a moderately unstable
airmass as convection spreads east toward the Mid-Atlantic.

Additional thunderstorm development is expected later in the
afternoon associated with another shortwave impulse spreading east
from IL into IN/OH. This activity will develop within strong
instability and rich boundary layer moisture. Modestly steep
midlevel lapse rates and effective shear greater than 40 kt will
support initial supercells. With time, sufficient clustering is
expected and bowing segments will be possible. Damaging wind and
hail will be the primary hazards, though a tornado or two also could
occur.

...Dakotas into Iowa...

Southeasterly low-level flow will transport mid/upper 60s dewpoints
north and west across SD, with 70s dewpoints common with southeast
extent across NE/IA/southern MN. This will support a corridor of
strong to extreme instability across the region. While coverage
remains uncertain, most guidance develops at least isolated
thunderstorms by evening. Elongated hodographs amid favorable deep
shear will support supercells and bows capable of large hail and
damaging winds. With time, it is possible sufficient clustering
occurs and upscale growth into a bowing MCS is possible as a
low-level jet develops overnight. If this occurs, a swath of
damaging winds is possible across parts of SD into northwest IA,
oriented along the stronger instability gradient.

...NE/CO/KS...

Scattered thunderstorms are expected to develop near a surface
trough across western NE/northeast CO by late afternoon/early
evening. This activity will spread east/southeast. Steep low-level
lapse rates will support strong outflow gusts and perhaps hail with
this activity.

...AZ...

Mid/upper easterly flow will persist today amid plentiful moisture
and strong heating. This will support thunderstorm development once
again across higher terrain. As storms propagate westward off the
higher terrain, isolated severe gusts will be possible.

..Leitman/Moore.. 08/10/2026


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SPC Aug 10, 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
0741 PM CDT Sun Aug 09 2026

Valid 100100Z - 101200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE MIDWEST...

...SUMMARY...
Severe storms are possible this evening into the overnight hours
across portions of the Midwest. Damaging winds will be the main
hazard with this activity. Additional strong to severe storms may
occur from western Nebraska into the Dakotas, and across Arizona.

...Midwest...

A bowing line of storms will continue to move east/southeast across
northern OH the next few hours. Occasional damaging gusts will be
possible with this activity before weakening after 04z as
instability wanes across northeast OH/western PA.

Model guidance continues to indicated additional convection will
develop across portions of eastern IA/northern IL this evening. This
activity may develop along residual outflow and a southward sagging
surface front as a low-level jet increases over the next few hours.
Thunderstorm clusters may grow into one or more MCSs moving east
across northern IL into IN and perhaps southern Lower MI.

...Northern/Central Plains...

Damaging wind and hail will be possible with convection moving
across western NE this evening. As ongoing storms track
east/southeast, they will encounter richer low-level moisture and
increasing instability. While stronger capping persisted with
eastward extent, even elevated storms will pose a severe risk as
they track across WW 0549.

Severe potential is less certain with northward extent across the
Dakotas. Low-level moisture will increase during the evening and
overnight hours, but currently, instability remains weak and capping
is strong. Isolated strong cells over northeast MT will continue to
develop southeast into limited instability but stronger vertical
shear. If storms can be maintained and additional development occurs
later this evening/overnight isolated hail and strong wind gusts
will be possible.

...AZ...

Similar to previous days, easterly midlevel flow will support
convection moving westward off higher terrain and across the lower
deserts within weak to moderate instability and steep low-level
lapse rates. Strong to severe gusts will be possible with this
activity.

..Leitman.. 08/10/2026


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SPC Aug 9, 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
1056 AM CDT Sun Aug 09 2026

Valid 091630Z - 101200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
OVER PARTS OF THE MIDWEST...AND TONIGHT OVER PARTS OF THE
DAKOTAS....

...SUMMARY...
Scattered damaging winds are possible today into this evening from
southern Wisconsin eastward across parts of northern Illinois,
southern Lower Michigan, northwest Ohio, and northern Indiana.
Damaging wind and hail may also occur across portions of the Dakotas
tonight.

...Midwest...
A persistent cluster of thunderstorms over southern WI appears
likely to continue southeastward through much of the day into parts
of IL/MI/IN and eventually OH. This activity will track near a
NW-SE oriented baroclinic zone, with dewpoints in the lower 70s to
the south. Eventually, low-level lapse rates will become
sufficiently steep to support damaging wind gusts along the leading
edge of the storms. Later tonight, strengthening southwesterly
low-level winds will enhance warm advection and lift over parts of
IL/IN, potentially leading to another round of strong/severe storms
capable of damaging winds and hail after 06z.

...Dakotas...
12z model guidance continues to decrease the confidence in overnight
severe storms, with some CAM solutions showing no thunderstorms.
Therefore have made the SLGT area smaller and focused where there is
highest confidence in isolated storms. Forecast soundings continue
to indicate steep mid-level lapse rates and strong deep shear,
providing a conditional risk of supercells if convection can be
sustained.

...AZ...
Thunderstorms are once again predicted to form along the Rim and
track westward toward the PHX metro area this evening. The strength
of the steering flow, instability, and mid-level moisture all appear
favorable for a severe risk. However, mesoscale details of the
evolution of the storms over high terrain will dictate the eventual
risk.

..Hart/Weinman.. 08/09/2026


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SPC Aug 9, 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
0737 AM CDT Sun Aug 09 2026

Valid 091300Z - 101200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE MIDWEST...

...SUMMARY...
Scattered damaging winds may occur today into this evening from
southern Minnesota and eastern Iowa eastward across parts of
northern Illinois, southern Wisconsin, southern Lower Michigan,
northwest Ohio, and northern Indiana. Damaging wind and hail are
also expected across portions of the Dakotas.

...Midwest...
Radar/satellite composite shows a corridor of showers/thunderstorms
from northern MO into southern MN and western WI associated with
isentropic lift on the nose of a 40-kt southwesterly LLJ. A
localized risk for hail/wind may accompany this activity this
morning as it shifts eastward across the MS River towards Lake MI
through midday. Considerable uncertainty remains regarding the
severe forecast for the eastern IA into the southern Great Lakes
portion of the Slight Risk. Showers/thunderstorms and related
convective debris/outflow will be influential on airmass recovery
later this afternoon. It seems plausible a warm front draped over
the Corn Belt this morning will slowly advance northward into the
southwest Great Lakes with an increasingly unstable airmass
developing to the south/west of this convectively augmented
baroclinic zone.

Model forecast soundings show ample CAPE aided by the northern rim
of lower to mid 70s F surface dewpoints into northern portions of
IL/IN. Adequately strong and vertically veering wind profiles will
support 30-40 kt effective shear magnitudes. Low-level SRH may also
be locally boosted in the vicinity of the warm front/effective
boundary, which could then play a role in severe potential if a
supercell or linear segments were to develop and favorably interact
within this corridor. Rather poor depiction of this morning's
thunderstorm evolution (i.e., 00z HREF members) casts large
uncertainty where a couple of more intense thunderstorm clusters
will ultimately develop. It seems the greatest potential for severe
will be centered over northern IL later this afternoon through the
evening, but confidence remains low regarding details and the need
for spatial refinements of the severe risk area and the need for
potential higher probabilities.

...Dakotas and western NE...
A surface front is expected to push southward across the central
Plains, becoming oriented across northern KS by tonight. Low-level
warm advection atop the boundary, and surface winds becoming
south/southeasterly with time will maintain 60s dewpoints across the
region. Within this post-frontal upslope regime, a reservoir of
mainly 60s F dewpoints will reside beneath moderate northwesterly
flow aloft. Supercell wind profiles and steep low-level lapse rates
will support initial storms capable of large hail and severe gusts,
especially as this activity over the western Dakotas moves
southeastward into richer moisture. A small cluster may eventually
evolve during the overnight with an attendant risk for severe gusts
and perhaps large hail.

...Southern Appalachians...
Scattered thunderstorm development is expected over higher terrain
within a seasonally moist and unstable airmass. Steepening
low-level lapse rates and high PW values may support locally strong
gusts with wet microbursts through early evening.

...AZ...
Modest easterly mid/upper flow will persist across the region on the
southern periphery of an upper high over the Four Corners. Another
day of hot conditions will promote steep lapse rates and modest
destabilization. As convection develops over higher terrain and
spread westward, strong outflow gusts may occur.

..Smith/Kerr.. 08/09/2026


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