SPC Apr 4, 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
0740 AM CDT Sat Apr 04 2026

Valid 041300Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE LOWER
GREAT LAKES/OHIO VALLEY...

...SUMMARY...
Severe storms capable of damaging winds and a tornado risk are
expected across parts of the Lower Great Lakes and middle/upper Ohio
River Valley, mainly this afternoon through early evening. Other
more isolated severe storms may occur across the Tennessee Valley,
Lower Mississippi Valley, and eastern part of Texas.

...Ohio/Eastern Indiana/Lower Michigan to Pennsylvania/New York...
A shortwave trough over the Upper Midwest early today will continue
northeastward toward the upper Great Lakes through tonight.
Cyclonically influenced strengthening deep-layer southwesterlies
(50+ kt 700 mb) will overspread Indiana/Michigan toward the Lower
Great Lakes, atop a steadily moistening/heating warm-sector boundary
layer along and north of the Ohio River.

This will be ahead of a surface low and cold front, that is
considerably augmented by generally weakening thunderstorms and
prevalent lingering clouds/outflows through the pre-dawn hours.
These residual factors cast uncertainty regarding the magnitude of
today's overall potential, but a formidable flow field and
guidance-advertised heating/steady diurnal destabilization will
still be supportive of at least some severe potential regionally as
storms redevelop and intensify this afternoon. This includes
damaging wind potential, particularly given the magnitude of
low/mid-tropospheric winds and boundary layer mixing, with some
tornado threat as well, mainly in vicinity of the triple
point/nearby warm front. Overall storm intensities should decrease
by mid/late evening, owing to nocturnal boundary-layer influences
and the primary upper-level system spreading away from the region.

...Tennessee Valley/Lower Mississippi Valley/Texas ...
While diminishing in intensity overnight, showers/thunderstorms
remain extensive and prevalent from the Mid-South/Ozarks
southwestward into North Texas, as a synoptic cold front otherwise
continues to progress southeastward across these regions. While
details are complexified by considerable cloud cover and lingering
storms, multiple corridors of reinvigorating storms should
materialize this afternoon where more appreciable cloud
breaks/heating occur. Downbursts/locally damaging winds will be the
primary severe hazard, but this is currently expected to be on a
relatively isolated/episodic basis.

..Guyer/Weinman.. 04/04/2026


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SPC Apr 4, 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
1259 AM CDT Sat Apr 04 2026

Valid 041200Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTHEAST LOWER
MICHIGAN...MUCH OF OHIO...AND PORTIONS OF WESTERN PENNSYLVANIA AND
NEW YORK....

...SUMMARY...
Strong-to-severe storms will be possible from eastern Texas
northeastward toward the Lower Great Lakes. Sporadic damaging winds
will be the most likely severe hazard throughout this corridor, with
the greatest likelihood across the Lower Great Lakes.

... Synopsis ...

A midlevel trough is forecast to move from the northern Plains into
Ontario on Saturday As this happens, a surface low should lift
northward from northern Illinois/southern Wisconsin into Ontario as
well and a surface cold front will accelerate eastward across the
Great Lakes and be approaching the East Coast by Sunday morning. To
the southwest, the cold front will not progress as quickly, but
should advance south and east through the day.

... Southeast Lower Michigan, Ohio, Western Pennsylvania, and
western New York ...

As the surface low lifts northward into Canada on Saturday, showers
and thunderstorms are expected to be ongoing along and ahead of the
trailing composite cold front/convective outflow. At the same time,
a surface warm front will lift slowly northward across Lower
Michigan. To the south of this front, and ahead of the cold
front/outflow, a moist airmass, characterized by low-to-mid 60Fs
dewpoints should be in place. Despite the strongest large-scale
ascent being displaced to the north and west of the warm sector and
weak midlevel lapse rates atop the warm sector, pockets of
insolation should be sufficient to destabilize the environment
enough to support some convective redevelopment along and ahead of
the composite outflow/cold front. Modest instability will combine
with seasonably strong low-level wind fields to support a convective
wind threat and an isolated tornado threat along the leading edge of
any sustained linear segments.

... Tennessee Valley southwest to eastern Texas ...

Widespread thunderstorms are expected to be ongoing across the
western portions of this area at the start of the forecast period.
These thunderstorms will likely be driven by convergence along the
east/southeast moving composite cold front/convective outflow
boundary, with the exact western edge of any severe threat
demarcated by where this boundary is located at the start of the
forecast period. Seasonably high precipitable water values should
support some threat for strong wind gusts in the most intense
thunderstorm cores. These thunderstorms are expected to continue
through the day, despite weakening large-scale ascent and vertical
wind shear as the midlevel low pulls farther away. Given the
seasonably high precipitable water values, modest insolation should
support MUCAPE values between 500 and 1000 J/kg (perhaps as high as
1500 J/kg) across portions of Texas, Louisiana, and Mississippi.
This may support a re-intensification of ongoing convection which
would be capable of sporadic damaging downbursts

..Marsh/Chalmers.. 04/04/2026


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SPC Apr 4, 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
0756 PM CDT Fri Apr 03 2026

Valid 040100Z - 041200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHWEST
TEXAS NORTHEAST INTO SOUTHEAST IOWA AND EAST INTO CENTRAL
ILLINOIS...

...SUMMARY...
Thunderstorms continue to evolve into an extensive line this evening
from Iowa to Oklahoma and northwest Texas. Damaging winds, hail, and
a couple of tornadoes remain possible through the overnight.

... 01Z Update ...

Thunderstorms continue to develop along and ahead of an advancing
cold front this evening. These storms should continue to increase in
number, growing upscale into an extensive linear MCS from Northwest
Texas northeastward into southern Iowa. Despite nocturnal
stabilization of the boundary layer, forcing along the cold front,
MUCAPE between 1000-2000 J/kg, and sufficient vertical shear should
support a continued hail and wind threat into the overnight hours,
especially across the southern portion of this area where updrafts
appear to be more robust than areas farther north. Given the moist
low-levels and a modest uptick in the low-level jet, a couple of
tornadoes may still occur as well.

Additional thunderstorms have developed eastward along the warm
front draped across southern Iowa east across Illinois, Indiana,
Ohio, and Pennsylvania. MUCAPE and vertical shear decrease with
eastward extent along the warm front, organized thunderstorms within
the frontal zone should support an localized hail and wind threat
for a few more hours. A tornado or two could also be realized with
any discrete/semi-discrete cell that can increase its resonance time
in the frontal zone, especially across central Illinois where better
instability and vertical shear exist.

..Marsh.. 04/04/2026


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SPC Apr 3, 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
1106 AM CDT Fri Apr 03 2026

Valid 031630Z - 041200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING OVER PARTS OF SOUTHERN IOWA...NORTHERN MISSOURI...AND
WESTERN ILLINOIS....

...SUMMARY...
Thunderstorms are expected to evolve into an extensive line this
evening from Iowa to Oklahoma and northwest Texas, with the primary
threats of large hail and damaging winds. A few tornadoes are also
possible in any supercells that can form ahead of the line over
parts of Iowa, Missouri, and central Illinois.

...MO/IA/IL...
Latest surface analysis shows a low over northeast KS. This low
will track northeastward across southern IA today, with the
associated warm front lifting northward into northern IL. The air
mass in the warm sector of the low will be relatively moist and
unstable with dewpoints in the lower 60s and afternoon MLCAPE values
of 2000 J/kg. Thunderstorms are expected to develop near the
surface low in IA, and more widely scattered storms eastward along
the warm front. A few supercells are possible across this region,
with a concern for tornadoes, large hail, and damaging winds in the
most intense cells.

...MO/KS/OK/TX...
An extensive line of thunderstorms is expected to form along the
cold front this afternoon from western MO into southeast KS and much
of OK. Ample low-level moisture and CAPE will be present ahead of
the storms, along with sufficient deep-layer shear for
rotating/bowing storm structures. Large hail and damaging winds
appear to be the main concern, but a tornado or two are also
possible.

..Hart/Wendt.. 04/03/2026


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