SPC Jul 28, 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
0800 PM CDT Mon Jul 27 2026

Valid 280100Z - 281200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE OHIO VALLEY...

...SUMMARY...
Thunderstorms with severe wind gusts and hail are expected this
evening across parts of the Ohio Valley. Additional storms with
severe wind gusts are also expected from Lower Michigan southward
into Ohio. A few strong gusts will also be possible in parts of the
central Plains and in south-central Arizona.

...Ohio Valley/Great Lakes...
On water vapor imagery, a mid-level shortwave trough is moving
southward through the Ohio Valley. Ahead of this feature, a moist
and unstable airmass is in place with surface dewpoints in the 70s
and low 80s F. The RAP has a pocket of strong instability located
from western Kentucky into southern Indiana, where MLCAPE is
estimated in the 3500 to 4500 J/kg range. Scattered strong to severe
storms are ongoing along the northern edge of the stronger
instability, and the storms are being supported by large-scale
ascent associated with the shortwave trough. In addition, the
WSR-88D VWP at Louisville has 0-6 km shear of 30 to 35 knots
suggesting a potential for organized severe storms will continue
this evening. Severe wind gusts will be possible with supercells and
short bowing line segments. The greatest coverage of severe is
expected to be over southern Indiana and far northern Kentucky...see
MCD 1774.

Further north into Lower Michigan, scattered strong thunderstorms
are ongoing ahead a subtle shortwave trough evident on water vapor
imagery. Short-term model forecasts suggest these storms will expand
in coverage and move southward across Lower Michigan into Ohio
during the late evening and early overnight period. Along this
corridor, the RAP has MLCAPE in the 1000 to 1500 J/kg range with 40
to 50 knot of deep-layer shear. This should support a wind-damage
threat with organized short line segments.

...Central Plains...
At mid-levels, a subtle shortwave trough is currently moving over
the top of a ridge in the central High Plains. Ahead of the
shortwave trough, scattered strong thunderstorms are ongoing along
the western edge of a pocket of strong instability. The RAP
currently shows MLCAPE over central Nebraska in the 4000 to 5500
range. Even though forecast soundings near the instability maximum
have low to mid-level wind speeds generally less than 20 knots, the
instability combined with very steep low-level lapse rates may be
enough for isolated severe wind gusts for a few more hours this
evening.

...Arizona...
The latest surface analysis shows a sufficiently moist airmass in
place over the southern half of Arizona, where dewpoints are mostly
in the mid to upper 50s F. Within the moist air, the RAP has a
pocket of moderate instability with MLCAPE in the 1500 to 2500 J/kg
range. Thunderstorm have developed along the northern edge of the
stronger instability. These storms will move westward across
south-central Arizona this evening, and may pose a threat for severe
wind gusts due to very steep low to mid-level lapse rates...MCD
1772.

..Broyles.. 07/28/2026


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SPC Jul 27, 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
0258 PM CDT Mon Jul 27 2026

Valid 272000Z - 281200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE LOWER GREAT LAKES AND MIDWEST STATES...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
CENTRAL AND NORTHERN HIGH PLAINS....

...SUMMARY...
Severe storms capable of strong to severe wind gusts and large hail
are expected across the Great Lakes and Midwest through tonight.
More sporadic occurrences of damaging wind are possible in the
Mid-Atlantic, Tennessee Valley, central High Plains, and southeast
Arizona.

...20z Update IL/IN...
An evolving convective cluster across northern IL/IN and southern
lower MI should continue to move south/southeast this afternoon.
Low-level convergence is maximized along a weak CAPE/ThetaE gradient
laying roughly near the IN/OH border. CAM guidance and observation
trends suggest this may provide a focus for convection through this
afternoon and evening gradually turning the cluster further
southward. Moderate buoyancy and 40+ kt of deep-layer shear parallel
to the boundary could support organized linear/bowing structures
with severe/damaging gusts and perhaps some QLCS tornadoes possible
across northern IN and possibly extending into western OH. However,
leading stratiform and cloud cover could limit the eastern extent of
the higher severe risk, and confidence in the convective evolution
is very low.

Additional development has been noted along the western flank of the
complex over northern IL, with another cluster of storms exiting
southern WI. It is possible that these new storms, and additional
ascent tied to a westerly low-level jet will support a second
cluster of severe storms eventually organizing and moving more south
across IL/IN. Hot surface temperatures (90-95 F) and a very large
reservoir of extreme buoyancy (MUCAPE 4000-5000 J/kg) extending into
IL and western IN would support a risk for widespread
severe/damaging gusts. Given the increased confidence in damaging
winds this afternoon/evening, have shifted 30% wind probabilities
farther south in IN.

...Central and northern High Plains...
Scattered storms ongoing over the high plains should increase in
coverage and intensity this afternoon. Steep mid-level lapse rates
could promote severe wind gusts with stronger downdrafts, along with
isolated hail. Minimal changes were made to the prior outlook, see
MCD#1767 and MCD#1768 for more information.

Additional scattered thunderstorms are ongoing over parts of the Mid
Atlantic/Southeast and southern AZ. These storms should continue
this afternoon with potential for sporadic damaging gusts owing to
heavy water loading and moderate buoyancy. Limited vertical shear
and only modest clustering suggest severe potential will remain
isolated before diminishing overnight.

..Lyons.. 07/27/2026

.PREV DISCUSSION... /ISSUED 1149 AM CDT Mon Jul 27 2026/

...Midwest/Ohio Valley...
A large upper ridge remains present today over the central
Plains/Rockies, with moderately strong northwest flow aloft from the
Midwest into the OH Valley. A very moist and unstable low-level air
mass resides from WI/IL into MI/IN/OH, where mostly clear skies will
result in hot afternoon temperatures and MLCAPE values over 3000
J/kg. Multiple clusters of intense thunderstorms are ongoing over
parts of WI tracking southeastward. These storms will move through
this reservoir of high CAPE, leading to the potential for an active
severe weather event today. However, details of how these clusters
evolve are uncertain.

Vertical shear across this region will support supercell structures,
capable of damaging winds, hail, and isolated tornadoes this
afternoon. However, the greater concern is if storms can congeal
into a southeastward bowing system and that sweeps across Lower MI,
eastern IL, IN, and western OH. Several morning CAM solutions
indicate that risk, with storms spreading into KY overnight before
weakening. Unfortunately, this synoptic pattern does not lend
itself to a high-confidence convective forecast.

...High Plains...
Widespread clouds are affecting parts of western NE this morning.
However, strong heating will occur north and south of these clouds,
leading to afternoon thunderstorms. The most active area will
likely be over the Black Hills region where damaging winds and hail
are possible. Farther south, widely scattered high-based
thunderstorms will affect eastern CO/western KS with a risk of
damaging wind gusts.


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SPC Jul 27, 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
0800 AM CDT Mon Jul 27 2026

Valid 271300Z - 281200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
MIDWEST/LAKE MICHIGAN VICINITY...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL
HIGH PLAINS...

...SUMMARY...
Severe storms capable of strong to severe wind gusts and large hail
are expected across the Great Lakes and Midwest through tonight.
More sporadic occurrences of damaging wind are possible in the
Mid-Atlantic, Tennessee Valley, central High Plains, and southeast
Arizona.

...Midwest/Great Lakes to the Ohio/Tennessee Valleys...
A complex forecast scenario again exists today complicated by
numerous mesoscale factors and well-above-normal short-term guidance
variability. There nonetheless is an appreciable broad regional
severe potential, at least conditionally, attributable to robust or
even extreme source-region buoyancy and an appreciable belt of
northwesterly flow aloft (50+ kt at 500 mb), which could easily
support well-organized wind-producing swaths regionally into the
afternoon and tonight.

A high-moisture-content airmass is prevalent regionally to the south
of a cold front that extends across South Dakota/Minnesota toward
Lake Superior. Several corridors of storms are ongoing early this
morning, including across the western Upper Peninsula of
Michigan/far northern Wisconsin, as well as southwest lower
Michigan, with some uptick in ACCAS/mid-level convection in the
predawn hours across eastern Iowa/far southwest Wisconsin.
Increasing daytime storms, in terms of coverage/intensity/
organization, may stem from, but are not limited to, these early day
corridors. Bouts of large hail will be possible given the degree of
vertical shear/buoyancy, and some tornado risk could exist, but the
most prominent concern would be for damaging wind potential,
particularly if one or more south/southeast-moving
forward-propagating clusters emerge, which currently appear most
probable this afternoon and tonight across eastern Wisconsin/western
Michigan and Lake Michigan vicinity southeastward into Indiana,
western Ohio, and Illinois.

...Central High Plains...
Moist, post-frontal surface flow is expected across much of
Nebraska/South Dakota, shifting from northerly early in the day to
more easterly by the afternoon. Dewpoints will initially be in the
mid to upper 70s F, although strong boundary-layer mixing will
likely result in dewpoints ranging from the upper 50s/low 60s across
the Nebraska Panhandle to the low 70s across eastern Nebraska. This
reservoir of low-level moisture coupled with strong heating and
steep mid-level lapse rates will result in a corridor of moderate to
extreme buoyancy from eastern Wyoming/northeast Colorado/southwest
South Dakota eastward across south-central
South Dakota and much of Nebraska.

Most of the guidance indicates a subtle, convectively augmented
vorticity maximum will progress eastward through the northern
periphery of the Four Corner upper ridge. This should contribute to
thunderstorm development across the high terrain, which would then
progress downstream into a more moist and unstable airmass. One or
more clusters could evolve, but the overall predictability of the
convective evolution is low. That said, environmental conditions
support the potential for strong to severe gusts, including the
potential for some over 75 mph.

...Mid-Atlantic States/Delmarva...
Isolated damaging wind potential will exist during the
afternoon/evening, especially near/east of I-95 in vicinity of a
surface trough, where marginal buoyancy and deep-layer shear could
support a few stronger updrafts/downdrafts.

...Southeast Arizona...
Isolated severe-caliber wind gusts are possible over southeast
Arizona as mid-level moisture and diurnal heating leads to scattered
storms over the higher terrain. Cells are expected to move westward
into warmer temperatures and deeper boundary-layer mixing, with PWAT
over 1.25" and steep low-level lapse rates supporting strong
convective outflows.

..Guyer/Wendt.. 07/27/2026


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SPC Jul 27, 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
0802 PM CDT Sun Jul 26 2026

Valid 270100Z - 271200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PORTIONS OF THE
UPPER MIDWEST AND WESTERN GREAT LAKES...

...SUMMARY...
Severe thunderstorms capable of large to very large hail, damaging
winds (possibly 75+ mph), and tornado risk remain likely from the
upper Mississippi Valley and Great Lakes southwestward into
Nebraska, mainly late this evening and tonight.

...Upper Midwest...
A very unstable environment remains in place across the region, with
the MPX, GRB, and DVN 00Z soundings sampling MLCAPE from 3100, 2900,
and 2800 J/kg, respectively. Surface observations show mid to upper
70s dewpoints on the warm side of the warm front extending from
north-central MN through northeast WI/far western Upper MI. A
thunderstorm has matured upstream of this corridor, with the
expectation it will remain strong to severe as it continues
southeastward. Modest low-level warm advection into this boundary
will also contribute to additional thunderstorms this evening and
overnight. Environmental conditions are still expected to support
large to very large hail early in the convective cycle while a more
cellular mode is likely. Thereafter, a trend towards bowing segments
capable of severe wind gusts is anticipated. A singular MCS could
eventually develop, with severe gusts possible as it moves southward
as well. Some gusts, both within the line segments and early in the
MCS lifecycle, could be significant (i.e. over 75 mph).

...TN Valley...
A cold-pool-driven MCS continues to propagate south-southeast at
approximately 40 kts. The downstream airmass is very moist, with
numerous sites reporting dewpoints in the low 80s. This moisture is
contributing to extreme buoyancy, with the recent 00Z BNA sounding
sampling 4500 J/kg of SBCAPE. This MCS is also oriented
perpendicular to the deep-layer vertical shear. All of these factors
will contribute to continued southward progression, with an
attendant risk for strong gusts likely extending into Middle TN this
evening.

...South-Central into Southeast SD into central NE...
Numerous attempts at deep convection along the weak surface trough
extending from south-central SD through central NE have failed thus
far. The window of opportunity for deep convection will likely
remain open for the next hour or two before building inhibition
associated with nocturnal cooling precludes mature convection. Until
that occurs, there remains a conditional risk for severe
thunderstorms capable of strong downdrafts and isolated large hail.

...Elsewhere...
Increasing thunderstorm coverage is possible across the Mid-Atlantic
over the next few hours as a shortwave trough progresses
southeastward across the region. Moderate vertical shear could
support updraft organization with deeper, more persistent
convection. Isolated damaging gusts and hail are possible with the
more organized storms. Isolated damaging gusts remain possible
across northern Wyoming and far southwest South Dakota as high-based
thunderstorms track northeastward across the region this evening.
Jackson Hole Wyoming reported a gust of 50 kt at 2353Z.

..Mosier.. 07/27/2026


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