SPC Apr 3, 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
0801 PM CDT Thu Apr 02 2026

Valid 030100Z - 031200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE SOUTHERN GREAT LAKES REGION...

...SUMMARY...
Ongoing severe thunderstorms across the Great Lakes this evening
will remain capable of producing damaging thunderstorm winds, a
couple of tornadoes, and some hail into the overnight hours.

... 01Z Update ...

A vigorous, negatively tilted trough continues to lift northeast
across the Upper Great Lakes this evening. Ahead of this wave,
strong ascent is supporting multiple clusters/bands of severe
convection across the Great Lakes -- one currently across Indiana
and Michigan within the cyclone's warm-conveyor belt and another
across Illinois and Wisconsin along the combined Pacific front and
dryline.

Despite the loss of diurnal heating, strong large-scale ascent and
low-level convergence along the front/dryline will support
thunderstorms into the overnight. Although the overall intensity of
the thunderstorms will gradually decrease with time, the strength of
the low-level wind fields will support a continued wind threat into
Lower Michigan overnight, with a modest QLCS-type tornado threat.

..Marsh.. 04/03/2026


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TRrYdM

SPC Apr 2, 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
0256 PM CDT Thu Apr 02 2026

Valid 022000Z - 031200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
EASTERN IOWA...NORTHERN ILLINOIS...AND SOUTHERN WISCONSIN...

...SUMMARY...
Severe thunderstorms capable of producing a few tornadoes remain
probable across parts of eastern Iowa, northern Illinois, and
southern Wisconsin this afternoon and evening. Additionally,
damaging thunderstorm winds will be possible from eastern Iowa
northeast into Michigan.

...20z Update IA, IL, MO and southern WI...
Rapid air mass modification is underway to the south of a warm front
lifting northward across the western Great Lakes and upper Midwest.
Clearing beneath the advancing mid-level dry slot may allow
temperatures to warm into the low 70s, with surface dewpoints near
60 F. This will support weak buoyancy amid very strong shear
profiles (0-1 km SRH >300 m2/s2) from observed VADs and regional
RAOBs.

Scattered thunderstorms and supercells ongoing over northern MO and
southern IA should mature and present a severe hazard over much of
the ENH area as they spread northeastward through this evening. A
few tornadoes (some strong and fast moving), hail and damaging gusts
are expected. Additional storms may develop within the warm conveyor
belt farther east across IL this afternoon/evening. Upscale growth
into one or more clusters with damaging gusts and a couple tornadoes
is the primary concern.

The main change with the 20z update was to trim thunderstorm and
severe probabilities to the west of the advancing cold front. See
the prior discussion for more information.

..Lyons.. 04/02/2026

.PREV DISCUSSION... /ISSUED 1113 AM CDT Thu Apr 02 2026/

...IA/IL/MO/WI...
Morning water vapor imagery shows a strong shortwave trough over
northeast KS, with an associated mid-level jet and dry-slot rotating
around the base of the trough into western MO. A deep surface low
currently south of OMA will track northeastward across IA this
afternoon, with a tight gradient of low-level moisture and
instability along the track of the low. Very strong low-level shear
and sufficient CAPE in the warm sector will pose a risk of
fast-moving supercells capable of damaging winds, tornadoes
(possibly strong), and hail. The area of greatest concern is over
eastern IA into northern IL and far southern WI. Perhaps the
biggest forecast uncertainty is the widespread cloud cover and
limited diurnal destabilization, but the approaching dry slot may
compensate by mid-afternoon and allow a period of afternoon heating.

The coverage of storms with southward extent is uncertain across
eastern MO and central/southern IL. Recent CAM solutions continue
to show only widely scattered discrete development across this
corridor. However, given the forecast of strong low-level shear and
favorable synoptic forcing, those storms that do form would pose a
risk of damaging winds and a few tornadoes.

...Eastern IL/IN/Lower MI...
Strong southerly low-level winds will maintain 60s dewpoints across
eastern IL/western IN, and result in the warm front lifting
northward into southern Lower MI by this evening. This will provide
a favorable environment for a few severe storms capable of damaging
winds and perhaps a few tornadoes.


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TRrRkR

SPC Apr 2, 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
0756 AM CDT Thu Apr 02 2026

Valid 021300Z - 031200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EASTERN
IOWA...NORTHERN ILLINOIS...AND FAR SOUTHERN WISCONSIN...

...SUMMARY...
Severe thunderstorms capable of producing a few tornadoes appear
probable across parts of eastern Iowa, northern Illinois, and
southern Wisconsin this afternoon. Additionally, damaging
thunderstorm winds will be possible from eastern Iowa northeast into
Michigan.

...Synopsis...
Early morning satellite and radar imagery show an extensive warm
conveyor, with embedded showers and thunderstorms, extending from
the southern Plains into the Upper Midwest, with some westward
branching noted over the Mid MO Valley. This warm conveyor is
associated with shortwave trough currently progressing through the
central Plains. Recent surface analysis places a surface low just
ahead of this wave over central KS, with a warm front extending
eastward from the low into the middle OH Valley and a dryline
extending south-southwestward from this low through the TX Trans
Pecos.

Expectation is for this shortwave to eject quickly northeastward
throughout the day, maintaining a negative tilt as it progresses
through the Mid MO Valley and Upper Midwest before ending the period
over northeastern Ontario. The associated surface low will move
quickly northeastward as well, progressing across southern and
eastern IA and southern WI before occluding over upper MI tonight.
Warm front attendant to this low will move northward as well,
bringing low 60s dewpoints into eastern IA, northern IL, and
southern WI before a cold front moves through. Strong to severe
thunderstorms are possible along and ahead of the cold front over
much of the Mid MS and Lower OH Valleys, with the highest potential
for severe thunderstorms from eastern Iowa, northern IL, and far
southern WI.

...Northern MO/Southern IA across southern WI/northern IL into Lower
MI...
Extensive area of showers and thunderstorms is currently ongoing
from central TX into the Upper Midwest, within the warm conveyor
mentioned in the synopsis. Moderate to strong southerly low-level
flow exists within this warm sector. Progression of the negatively
tilted shortwave and associated surface low mentioned in the
synopsis will lead to a strengthening of this low-level flow, with
attendant moisture advection into more of the Mid MS Valley. Some
eastward displacement of the warm conveyor is anticipated, leaving
the potential for airmass destabilization ahead of the surface low
and cold front. This is supported by most of the guidance, which
depicts a corridor of surface-based buoyancy and little to no
convective inhibition from eastern IA/northern IL into central/east
TX by the early afternoon.

Best forcing for ascent within this corridor will be over the Upper
Midwest and Mid MS Valley, particularly from southern/eastern IA
into northern IL/southern WI, as both the shortwave and surface low
move through the region. The strongest vertical shear will be over
this region as well, supporting the potential for supercells with
the initial, more cellular development. Very strong low-level shear
supports a heightened tornado potential with any supercells,
including the possibility of strong (EF2+) tornadoes. Given the
linear forcing along the approaching cold front, a transition to a
more linear storm mode is anticipated, although there is some
uncertainty to how fast this transition occurs. The strength of the
low-level flow supports a continued risk for tornadoes within any
convective lines, but the primary hazard once any lines develop will
become strong gusts. Kinematic fields are strong enough to support
60 to 80 mph gusts. Additionally, despite weakening buoyancy, strong
ascent and robust kinematic fields support the potential for
damaging gusts across much of Lower MI later tonight.

...Mid MS and Lower OH Valleys into the Mid-South...
As previously mentioned, showers and thunderstorms are currently
ongoing from central TX into the Upper Midwest, within the extensive
warm conveyor mentioned in the synopsis. There is some potential for
reintensification of these showers and thunderstorms late this
afternoon/early evening from central/eastern IL into the northeast
AR/MO Bootheel, supported my modest destabilization and increasing
ascent. Storm structures will likely be somewhat shallow, but strong
flow will still support the potential for damaging gusts within any
bowing line segments. A brief tornado is possible as well.

Airmass destabilization is also anticipated west of this warm
conveyor, but ahead of the cold front, from central IL into
central/southern MO and northern AR. Much of this area will be
displaced south and west of the departing shortwave trough and
surface low, limiting large-scale ascent. However, some modest
ascent is possible along a weak lagging upper trough, which could be
enough to promote additional development. If updrafts can be
maintained, parameters support the potential for strong to severe
storms capable. Large hail is the primary risk, but a
low-probability tornado risk exists as well.

..Mosier/Bentley.. 04/02/2026


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TRr6tH

SPC Apr 2, 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
0102 AM CDT Thu Apr 02 2026

Valid 021200Z - 031200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
IOWA...NORTHERN ILLINOIS...AND FAR SOUTHERN WISCONSIN...

...SUMMARY...
Severe thunderstorms capable of producing a few tornadoes appear
probable across parts of eastern Iowa, northern Illinois, and
southern Wisconsin this afternoon. Additionally, damaging
thunderstorm winds will be possible from eastern Iowa northeast into
Michigan.

... Overview ...

A negatively tilted trough will quickly lift northward through the
Plains and across the Great Lakes today and tonight. As this occurs,
a modest surface low will race northeast from north-central Kansas
this morning into Ontario by Friday morning. Attendant to this
surface low, a west-east oriented warm front will lift northward
across the Great Lakes during the day and a north-south cold front
will push east across the region during the late afternoon and
overnight.

... Eastern Iowa east-north into Michigan ...

A strong low-level jet at the start of the forecast period will
support widespread showers and thunderstorms across the area. The
low-level jet will strengthen through the morning as the midlevel
trough approaches and the H850 low intensifies. This will maintain
showers and thunderstorms through at least midday across Iowa and
Illinois before the H850 low moves far enough north and east for the
core of the low-level jet to focus farther east, taking the
precipitation with it.

In the wake of the morning/early afternoon convection, a narrow
corridor of destabilization should occur across central/eastern Iowa
and northwest Illinois to the south of the warm front and east of
the cold front. Scattered supercells are expected to develop along
the cold front during the afternoon where MUCAPE in excess of 1000
J/kg and deep-layer shear on the order of 45 knots exists. Strong
low-level kinematic fields will support a tornado and wind threat
with these initial storms, and, despite modest lapse-rates, the
presence of supercells within a modestly unstable environment will
support some hail potential.

By late afternoon/early evening these supercells should move into a
less stable environment characterized by decreasing CAPE but
increasing low-level shear. Current expectation is that the initial
discrete storms will eventually grow upscale into one or more linear
segments, along the advancing cold front. Despite the decreasing
instability, the strength of the low-level wind field will support a
continued wind threat eastward into Lower Michigan during the
evening and overnight hours.

... Northeast Arkansas, Southeast Missouri, western Tennessee, and
western Kentucky ...

Isolated thunderstorms will be possible during the afternoon along
and ahead of the surface cold front, where modest warm-air advection
is forecast to persist through the day. Despite weakening kinematic
fields, deep-layer shear on the order of 30 knots and MUCAPE between
1000-2000 J/kg will support at least some severe potential --
including a tornado or two -- during the late afternoon and early
evening.

..Marsh/Chalmers.. 04/02/2026


Read more CHECK UPDATE ZOOM GRAPHIC


http://dlvr.it/TRqnCx