SPC Apr 15, 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
1253 AM CDT Wed Apr 15 2026

Valid 151200Z - 161200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN PLAINS...MIDWEST...AND INTO THE GREAT LAKES...

...SUMMARY...
Severe thunderstorms posing a risk for large hail, strong wind
gusts, and a couple of tornadoes will be possible across portions of
the southern Plains toward the Great Lakes this afternoon and
evening.

...Synopsis...
A migratory upper-level wave is evident in water-vapor imagery over
northern Mexico. This feature will lift northeastward into the
Plains through the day, resulting in the eastward progression of a
modest surface cyclone from the central High Plains into eastern NE
by late afternoon. A broad, uncapped, and moderately sheared warm
sector will be in place from the southern Plains into the mid-MS
Valley and eastward into the Great Lakes/OH Valley. Strong to severe
thunderstorm development appears probable across much of this warm
sector, whether induced by ascent ahead of the primary upper wave or
by localized mesoscale boundaries.

...Iowa and northern Missouri...
Thunderstorm development appears likely by late afternoon from
central IA into northern MO in the vicinity of the surface low.
Stronger mid-level height falls compared to previous days lends
higher confidence in thunderstorm development, and 50-60 knot 500 mb
flow overspreading much of the warm sector will support organized
convection, including the potential for splitting supercells capable
of very large hail and tornadoes across IA and northern MO. A
focused zone of higher tornado potential may emerge roughly along
the I-80 corridor where backed low-level winds along the effective
warm front will locally augment SRH and could support a strong
tornado. HREF/REFS guidance both show the strongest UH signals
across this zone, warranting higher (5%) tornado probabilities.

...Ozarks into Oklahoma and north Texas...
Further south, initially discrete cells are anticipated along the
dryline from southeast KS into OK and north TX by mid-afternoon.
Despite somewhat higher confidence in storm development compared to
previous days, mean flow vectors along the boundary may promote
clustering and upscale growth within a few hours after initiation.
This scenario appears to be reflected in recent HREF/REFS guidance
in the form of numerous, but weak, UH streaks, as well as in
deterministic CAM solutions that depict one or more convective bands
emerging by early evening. Additionally, guidance hints at the
potential for morning convection across parts of OK and the Ozark
Plateau. It remains unclear what influence - if any- this activity
will have on the southern Plains warm sector or if any outflow
boundaries can emerge and focus a higher severe threat along
mesoscale corridors. Given these uncertainties, all severe
probabilities were expanded to account for the fairly wide envelope
of potential outcomes, most of which will likely feature the
potential for severe hail, wind, and tornadoes.

...Great Lakes into New England...
The combination of low to mid-60s dewpoints and the eastward
advection of an EML will support MLCAPE values upwards of 1000-1500
J/kg across much of the Great Lakes region with gradually
diminishing buoyancy with eastward extent towards the New England
coast. Aloft, 40-50 knot westerly mid-level winds will remain in
place within the crest of a modest ridge, establishing a zonal
corridor of a buoyant and moderately sheared environment. It appears
likely that multiple outflow boundaries and/or mid-level
perturbations associated with upstream MCSs across MI, AR, and IA
will likely reside within the warm sector by peak heating.
Thunderstorm development along or in the vicinity of these features
will support multiple corridors of strong to severe convection. This
scenario is depicted by most recent CAMs, which show multiple
convection bands traversing the warm sector through early evening.
However, exactly where these bands will become established (and
where corridors of higher severe potential will emerge) remains
uncertain given variance in recent guidance.

..Moore/Wendt.. 04/15/2026


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SPC Apr 14, 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
0236 PM CDT Tue Apr 14 2026

Valid 142000Z - 151200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MIDWEST/SOUTHERN GREAT LAKES AND SOUTHERN/CENTRAL PLAINS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHEAST...

...SUMMARY...
Severe thunderstorms are expected this afternoon through tonight
from the southern Plains into the Midwest. Large to giant hail,
several tornadoes (some strong), and swaths of severe/damaging gusts
are all likely, particularly from Iowa into the southern Great
Lakes.

...20Z Update...
A complex yet active severe weather day remains in the forecast for
portions of the Midwest-OH Valley into the Southern Plains this
afternoon into early tonight. While several lines were slightly
adjusted to account for the latest guidance consensus, the following
substantial changes and/or decisions were made:

1.) 30 percent wind probabilities were expanded southwestward into
southwest and central OK to account for the possibility of more
rapid upscale growth into one or more wind-producing MCSs or linear
segments.

2.) Category 1/Marginal Risk probabilities for severe wind and hail
were expanded west-southwest into NE along a frontal boundary to
account for two possible scenarios. First, an isolated strong storm
may develop within the next few hours along the boundary as a
consequence of strong diurnal heating. Second, late tonight, there
is low potential for gravity-wave associated convection on the
immediate cool side of the frontal boundary, atop a stable boundary
layer.

3.) Confidence is still too low for supercells across the Midwest to
remain discrete for long periods of time, which would warrant a
Categorical Moderate risk upgrade. Nonetheless, should a dominant
supercell become sustained and discrete for at least a few hours,
especially along the warm front over northeast IA into southern WI,
a sustained and intense tornado will be possible.

The rest of the forecast (see below) remains on track.

..Squitieri.. 04/14/2026

.PREV DISCUSSION... /ISSUED 1130 AM CDT Tue Apr 14 2026/

...Synopsis...
An active severe weather day is anticipated for much of the
southern/central Plains into the Midwest/Great Lakes and parts of
the Northeast. The primary upper trough centered over the Four
Corners late this morning will eject east-northeastward towards the
southern/central Plains by this evening, while a separate mid-level
shortwave trough over the northern Plains/Upper Midwest will also
move east-northeastward across the Upper Great Lakes into Ontario.
Another convectively enhanced low-amplitude shortwave trough will
also develop eastward across the Lower Great Lakes into the
Northeast.

Recent surface analysis indicates multiple surface lows, with one
over southern Ontario and another over southeast NE/northeast KS. A
seasonably rich/moist low-level airmass exists to the south of a
front extending between these two lows, with surface dewpoints
already in the low to mid 60s across much of the southern/central
Plains to the east of a dryline. Both the dryline in the
southern/central Plains and developing warm front in the
Midwest/southern Great Lakes will likely serve as foci for intense
thunderstorms this afternoon and evening, including the potential
for several supercells.

...Midwest/Ohio Valley/Great Lakes...
A complex scenario for severe thunderstorms remains apparent across
the Midwest/OH Valley into the southern Great Lakes today, with
multiple outflow boundaries from earlier convection rendering
greater than usual uncertainty with the southward extent of possible
thunderstorm development in IL/IN/OH. In general, continued
low-level warm advection from the central Plains into the Midwest/OH
Valley will support a moistening/destabilizing airmass through the
afternoon as a northern-stream shortwave trough moves eastward
across the Upper Midwest. A surface warm front will extend
northeastward from a weak surface low in IA across southern WI and
Lower MI. It still appears likely that multiple intense supercells
will develop by 20-21Z along/near this boundary in IA/southern
WI/northern IL in a very favorable airmass for significant severe
hail given strong deep-layer shear and the presence of steep
mid-level lapse rates. Low-level shear is expected to gradually
strengthen through the evening in tandem with a modestly increasing
south-southwesterly low-level jet.

Any supercells than can remain on the warm/south side of the front
will be capable of producing tornadoes, a few of which could be
strong (EF-2/3). Some consideration was given to including greater
tornado probabilities and a Moderate Risk (level 4 of 5) focused
across southern WI/far northern IL. But, convection may have a
tendency to grow upscale fairly quickly this evening, so confidence
was not high enough for a categorical upgrade at this time.
Regardless, very large to giant hail (potentially up to 3-4 inches
in diameter) will be a threat with sustained supercells, and a swath
of severe/damaging winds appears likely with a convective cluster
spreading eastward across southern Lower MI this evening into
tonight.

A somewhat separate area of severe potential should also exist
farther south across central IL into IN/OH this afternoon and
evening. Greater low-level moisture and related instability are
expected to exist across these areas compared to locations farther
north. While large-scale forcing should remain fairly weak/nebulous
across this region, a remnant outflow boundary may provide a focus
for supercell development across central IL into IN by 20-21Z. Have
expanded the Slight Risk for large hail, damaging winds, and perhaps
a few tornadoes southward across these areas to account for this
still somewhat uncertain potential.

...Southern/Central Plains...
12Z observed soundings from DRT/MAF/FWD/OUN/TOP show the presence of
steep mid-level lapse rates atop rich low-level moisture (generally
14-15 g/kg mean mixing ratios) along/east of the surface dryline.
Southwesterly mid-level flow and modest ascent preceding the upper
trough over the Southwest/southern Rockies will gradually overspread
the warm sector by mid to late afternoon. Moderate to strong
instability (MLCAPE around 2000-3000 J/kg, locally stronger
possible) and 35-45 kt of deep-layer shear will support multiple
intense supercells. Explosive convective initiation across parts of
western OK into south-central/southeast KS is expected by 20-21Z as
lingering MLCIN erodes with filtered daytime heating and as
convective temperatures are breached.

The overall thermodynamic and kinematic environment appears quite
favorable for very large to potentially giant hail (up to 3-4 inches
in diameter) with any supercells that spread east-northeastward
through the afternoon/evening. A gradually strengthening low-level
jet across OK/KS by 00Z will also support a threat for a few
tornadoes, a couple of which could be strong as low-level hodographs
become enlarged. Gradual upscale growth/clustering should occur with
time through the evening, with some risk for severe/damaging winds.
The Enhanced Risk has been expanded a bit northeastward into
south-central/southeast KS for a focused severe wind corridor.
Farther south along the length of the dryline in TX, isolated to
scattered supercells may develop this afternoon and evening, with a
risk for mainly large to very large hail and occasional severe
gusts.

...Northeast...
Ongoing convection across southern Ontario and the Lower Great Lakes
will continue to track eastward this afternoon into NY and parts of
New England in tandem with a low-amplitude shortwave trough. Gradual
clearing of low/mid-level clouds has already encouraged surface
temperatures to warm into the 70s along/south of west-east oriented
front. Thunderstorms are expected to gradually increase in coverage
and intensity as weak to locally moderate instability and strong
deep-layer shear support organized updrafts, including the potential
for some supercells initially. The greatest severe risk will
probably be scattered damaging winds given a tendency for convection
to consolidate into one or more clusters. But, an isolated severe
hail threat may exist with any sustained supercell, along with some
chance for a tornado or two near the front where low-level shear
will be locally enhanced.


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SPC Apr 14, 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 Tue Apr 14 2026

Valid 141630Z - 151200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MIDWEST/SOUTHERN GREAT LAKES AND SOUTHERN/CENTRAL PLAINS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHEAST...

...SUMMARY...
Severe thunderstorms are expected this afternoon through tonight
from the southern Plains into the Midwest. Large to giant hail,
several tornadoes (some strong), and swaths of severe/damaging gusts
are all likely, particularly from Iowa into the southern Great
Lakes.

...Synopsis...
An active severe weather day is anticipated for much of the
southern/central Plains into the Midwest/Great Lakes and parts of
the Northeast. The primary upper trough centered over the Four
Corners late this morning will eject east-northeastward towards the
southern/central Plains by this evening, while a separate mid-level
shortwave trough over the northern Plains/Upper Midwest will also
move east-northeastward across the Upper Great Lakes into Ontario.
Another convectively enhanced low-amplitude shortwave trough will
also develop eastward across the Lower Great Lakes into the
Northeast.

Recent surface analysis indicates multiple surface lows, with one
over southern Ontario and another over southeast NE/northeast KS. A
seasonably rich/moist low-level airmass exists to the south of a
front extending between these two lows, with surface dewpoints
already in the low to mid 60s across much of the southern/central
Plains to the east of a dryline. Both the dryline in the
southern/central Plains and developing warm front in the
Midwest/southern Great Lakes will likely serve as foci for intense
thunderstorms this afternoon and evening, including the potential
for several supercells.

...Midwest/Ohio Valley/Great Lakes...
A complex scenario for severe thunderstorms remains apparent across
the Midwest/OH Valley into the southern Great Lakes today, with
multiple outflow boundaries from earlier convection rendering
greater than usual uncertainty with the southward extent of possible
thunderstorm development in IL/IN/OH. In general, continued
low-level warm advection from the central Plains into the Midwest/OH
Valley will support a moistening/destabilizing airmass through the
afternoon as a northern-stream shortwave trough moves eastward
across the Upper Midwest. A surface warm front will extend
northeastward from a weak surface low in IA across southern WI and
Lower MI. It still appears likely that multiple intense supercells
will develop by 20-21Z along/near this boundary in IA/southern
WI/northern IL in a very favorable airmass for significant severe
hail given strong deep-layer shear and the presence of steep
mid-level lapse rates. Low-level shear is expected to gradually
strengthen through the evening in tandem with a modestly increasing
south-southwesterly low-level jet.

Any supercells than can remain on the warm/south side of the front
will be capable of producing tornadoes, a few of which could be
strong (EF-2/3). Some consideration was given to including greater
tornado probabilities and a Moderate Risk (level 4 of 5) focused
across southern WI/far northern IL. But, convection may have a
tendency to grow upscale fairly quickly this evening, so confidence
was not high enough for a categorical upgrade at this time.
Regardless, very large to giant hail (potentially up to 3-4 inches
in diameter) will be a threat with sustained supercells, and a swath
of severe/damaging winds appears likely with a convective cluster
spreading eastward across southern Lower MI this evening into
tonight.

A somewhat separate area of severe potential should also exist
farther south across central IL into IN/OH this afternoon and
evening. Greater low-level moisture and related instability are
expected to exist across these areas compared to locations farther
north. While large-scale forcing should remain fairly weak/nebulous
across this region, a remnant outflow boundary may provide a focus
for supercell development across central IL into IN by 20-21Z. Have
expanded the Slight Risk for large hail, damaging winds, and perhaps
a few tornadoes southward across these areas to account for this
still somewhat uncertain potential.

...Southern/Central Plains...
12Z observed soundings from DRT/MAF/FWD/OUN/TOP show the presence of
steep mid-level lapse rates atop rich low-level moisture (generally
14-15 g/kg mean mixing ratios) along/east of the surface dryline.
Southwesterly mid-level flow and modest ascent preceding the upper
trough over the Southwest/southern Rockies will gradually overspread
the warm sector by mid to late afternoon. Moderate to strong
instability (MLCAPE around 2000-3000 J/kg, locally stronger
possible) and 35-45 kt of deep-layer shear will support multiple
intense supercells. Explosive convective initiation across parts of
western OK into south-central/southeast KS is expected by 20-21Z as
lingering MLCIN erodes with filtered daytime heating and as
convective temperatures are breached.

The overall thermodynamic and kinematic environment appears quite
favorable for very large to potentially giant hail (up to 3-4 inches
in diameter) with any supercells that spread east-northeastward
through the afternoon/evening. A gradually strengthening low-level
jet across OK/KS by 00Z will also support a threat for a few
tornadoes, a couple of which could be strong as low-level hodographs
become enlarged. Gradual upscale growth/clustering should occur with
time through the evening, with some risk for severe/damaging winds.
The Enhanced Risk has been expanded a bit northeastward into
south-central/southeast KS for a focused severe wind corridor.
Farther south along the length of the dryline in TX, isolated to
scattered supercells may develop this afternoon and evening, with a
risk for mainly large to very large hail and occasional severe
gusts.

...Northeast...
Ongoing convection across southern Ontario and the Lower Great Lakes
will continue to track eastward this afternoon into NY and parts of
New England in tandem with a low-amplitude shortwave trough. Gradual
clearing of low/mid-level clouds has already encouraged surface
temperatures to warm into the 70s along/south of west-east oriented
front. Thunderstorms are expected to gradually increase in coverage
and intensity as weak to locally moderate instability and strong
deep-layer shear support organized updrafts, including the potential
for some supercells initially. The greatest severe risk will
probably be scattered damaging winds given a tendency for convection
to consolidate into one or more clusters. But, an isolated severe
hail threat may exist with any sustained supercell, along with some
chance for a tornado or two near the front where low-level shear
will be locally enhanced.

..Gleason/Chalmers.. 04/14/2026


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SPC Apr 14, 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
1250 AM CDT Tue Apr 14 2026

Valid 141200Z - 151200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE MIDWEST...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL
TO SOUTHERN PLAINS AND PARTS OF THE NORTHEAST...

...SUMMARY...
Severe thunderstorms are expected this afternoon through tonight
from the southern Plains to the Great Lakes. Large to very large
hail, a few tornadoes (some strong), and damaging wind gusts will be
possible, particularly across parts of eastern Iowa, northern
Illinois, and southern Wisconsin. Additional severe storms, mainly
producing strong wind gusts, will be possible across parts of the
Northeast this afternoon.

...Synopsis...
An upper wave is evident in recent water-vapor imagery across the
southern Great Basin. This trough will translate east into the
Plains through today, reaching the Great Lakes region by tonight.
This will support slight deepening of a diffuse surface low analyzed
over the central High Plains as it drifts east towards the lower MO
River Valley. Ahead of the low, an expansive warm sector
(characterized by widespread mid to upper 60s dewpoints) remains in
place from the southern Plains northeastward into the upper MS
Valley region. Strong to severe thunderstorms are expected along a
composite outflow boundary/warm front from eastern IA into southern
WI/northern IL as well as along a dryline draped from eastern KS
into OK and TX. Further east, a mid-level wave associated with
ongoing convection over the Great Lakes will support
re-intensification/re-development of strong/severe storms across the
Northeast.

...Midwest...
An outflow boundary emanating from the ongoing MCS across the Great
Lakes will likely be draped across the Midwest early this morning.
This boundary is forecast to drift northward within a southerly flow
regime as an effective warm front ahead of the approaching surface
low and upper wave. Latest guidance generally depicts this boundary
stalling across eastern IA into southern WI by late afternoon when
daytime heating and ascent ahead of the upper wave will erode
inhibition and promote convective initiation along the boundary.

Dewpoints in the mid to upper 60s coupled with steep mid-level lapse
rates (already noted in upstream 00z RAOBs) will support MLCAPE
values near 2500 J/kg by late afternoon. Moderate buoyancy combined
with 45-55 knots of effective bulk shear will be highly favorable
for organized convection. Capping at the base of the EML should
initially limit thunderstorm coverage and favor discrete supercells
along the boundary. In addition to very large hail (possibly up to
2-3 inches in diameter), enhanced low-level SRH along the boundary
may support a corridor of locally higher tornado potential,
including the potential for significant tornadoes. With time,
easterly storm motions along the boundary will promote upscale
growth with an increasing wind threat heading into the late evening
hours.

The primary uncertainty will be the location of the boundary by late
afternoon. 30% hail and 10% tornado probabilities were adjusted to
reflect the most likely placement of the boundary based on a
consensus of guidance; however, exact placement of the boundary will
be conditional on the precise evolution of the morning MCS.
Similarly, how quickly upscale growth occurs after initiation may
modulate the duration of the significant hail/tornado threat.

...Kansas into Oklahoma and Texas...
Modest height falls across the central to southern Plains combined
with weak convergence along the dryline will likely support isolated
to perhaps scattered thunderstorms from eastern KS southward into TX
this afternoon. Consensus among latest HREF/REFS guidance is that
initiation is most probable across northwest TX into central OK -
possibly ahead of a subtle mid-level wave, though in reality the
unfocused nature of the broad-scale ascent suggests that initiation
will be possible anywhere along the dryline where low-level
convergence can be maximized. Regardless, ample buoyancy within the
warm sector (2500-3000 J/kg MLCAPE sampled in evening RAOBs) coupled
with 30-40 knots of effective bulk shear will support supercells
with an attendant threat for large hail (possibly exceeding 2 inches
in diameter). Some tornado threat will likely materialize around and
after 00 UTC as the nocturnal jet strengthens and enlarges low-level
hodographs.

...Northeast...
A low-amplitude upper wave associated with an ongoing MCS across the
Great Lakes will migrate eastward towards the Northeast through the
day. Residual convection associated with the MCS may linger through
morning before re-intensifying by early afternoon as daytime heating
supports steepening low-level lapse rates and increasing MLCAPE
values (likely up to the 500-1000 J/kg range). While buoyancy will
likely remain weak, 35-40 knot bulk shear through the CAPE-bearing
layer and focused ascent ahead of a low-amplitude upper wave will
likely support organization of convective bands with an attendant
threat for strong to severe winds.

..Moore/Wendt.. 04/14/2026


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