ACUS01 KWNS 021250
SWODY1
SPC AC 021248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Wed Apr 02 2025

Valid 021300Z - 031200Z

...THERE IS A HIGH RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE
MID-SOUTH AND LOWER MISSISSIPPI VALLEY...

...SUMMARY...
A tornado outbreak is expected today and tonight from parts of the
lower Mississippi Valley into the Mid-South and lower Ohio Valley.
Numerous tornadoes, along with multiple EF3+ tornadoes, appear
likely. In addition, tornadoes, significant severe wind gusts, and
large hail to very large hail will be possible across a broad area
from north Texas northeastward to the southern Great Lakes.

...Synopsis...
A strong mid/upper-level trough with associated 100-120 kt mid-level
jet streak will advance quickly northeastward today across the Upper
Midwest and Great Lakes. A broader area of 50-70+ kt southwesterly
mid-level flow will persist over much of the southern Plains into
the lower/mid MS Valley and OH Valley. At the surface, the primary
low over far eastern NE/western IA this morning is forecast to
develop northeastward in tandem with the upper trough today,
eventually reaching the Upper Midwest by this evening. A trailing
cold front will continue east-southeastward across the southern
Plains and Ozarks today, before eventually stalling and lifting
northward as a warm front tonight. Weak secondary surface low
development is possible this afternoon and evening along or just
ahead of the front across AR into the Mid-South.

...Ozarks into the Lower/Mid Mississippi Valley, Mid-South, Ohio
Valley, and Southern Great Lakes...
Robust convection is ongoing this morning from northern MO
southwestward to southern OK and north TX along/near the cold front.
Even with some capping concerns noted on area soundings ahead of
this activity, a very strong (60-70 kt) southerly low-level jet is
providing ample low-level moisture transport to support continued
convective intensity. Steep mid-level lapse rates and strong
deep-layer shear are also fostering some embedded supercell
structures, with associated large hail threat. Otherwise, given the
strength of the low-level flow and very strong effective SRH,
scattered severe/damaging winds and a few tornadoes will remain the
primary threats with this line of convection as it continues
eastward this morning across the remainder of OK into AR and MO. A
strong tornado may occur with any sustained surface-based supercell.

The effect that this morning convection has on downstream afternoon
severe potential across the lower/mid MS Valley may be substantial.
Most guidance shows either a gradual weakening trend with the line
by late morning/early afternoon, or a devolution into a broken line
of supercells. Mid/high-level cloud debris could inhibit daytime
heating to some extent across much of the warm sector, and the
northern extent of the weakening line over northern MO may serve as
a cutoff for surface-based thunderstorms across the Midwest and OH
Valley later today. Even with these continued uncertainties, it
appears likely that a corridor of moderate to strong instability
will develop this afternoon across the lower MS Valley into the
Mid-South and lower OH Valley, generally ahead of whatever remains
of the ongoing/morning convection. With more nebulous/weaker
large-scale ascent over these regions given their spatial
displacement from the ejecting upper trough, there may be a more mixed/supercell mode this afternoon/evening, particularly with
southward extent.

Current expectations are for several intense supercells and clusters
to develop by 20-00Z from far northern LA into eastern AR, northwest
MS, western TN/KY, and southeast MO, and southern IL/IN. This region
appears to have the most favorable overlap of moderate to strong
instability, strong deep-layer shear, and ample low-level shear to
support multiple tornadic storms. With most guidance showing
enlarged, curved hodographs through the boundary layer, and
effective SRH forecast to generally range 250-400+ m2/s2, several
strong tornadoes are likely. Multiple EF-3+ tornadoes should also
occur given the very favorable parameter space forecast, but this
high-end tornado potential may be dependent on a relative lack of supercell/cluster interactions, which are difficult to pinpoint.
Still, based on latest high-resolution guidance trends showing
multiple intense supercells developing, the High Risk has been
expanded a bit southward with this update to include more of eastern
and south-central AR. The tornado and severe/damaging wind threat
will likely continue after dark, with updraft interactions
suggesting a messy mode, with clusters/lines and embedded supercells
all possible.

In addition to the tornado threat, large to very large hail (up to
2-3 inches in diameter) and severe/damaging wind gusts may occur
with these supercells and bowing clusters. A linear mode appears
more likely with northward extent across the mid MS Valley into the
southern Great Lakes as the cold front continues eastward today.
But, this area will also have less time to destabilize ahead of the
ongoing convection, which casts some uncertainty on the northern
extent of the substantial severe threat. Have trimmed the
Marginal/Slight Risks some across the Upper Midwest, but the
Enhanced Risk remains unchanged for now. Some risk for supercells
ahead of the line/clusters will exist across the OH Valley/Midwest.
But, confidence in this scenario occurring was not great enough to
expand the Moderate Risk for tornadoes northward into more of IN and
western OH.

...Southern Plains...
With the cold front expected to stall and eventually begin lifting
northward tonight, additional supercells may develop late in tandem
with ascent preceding another shortwave trough and a strengthening
southerly low-level jet. With steep mid-level lapse rates present
and ample MUCAPE and deep-layer shear, this convection should pose a
threat for mainly large to very large hail.

..Gleason/Leitman.. 04/02/2025

$$
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ACUS01 KWNS 021627
SWODY1
SPC AC 021626

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1126 AM CDT Wed Apr 02 2025

Valid 021630Z - 031200Z

...THERE IS A HIGH RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO
EARLY TONIGHT FROM EASTERN ARKANSAS INTO THE LOWER OHIO VALLEY...

...SUMMARY...
A tornado outbreak is expected this afternoon into early tonight
from parts of the lower Mississippi Valley into the Mid-South and
lower Ohio Valley. Numerous tornadoes, along with multiple EF3+
tornadoes, appear likely. In addition, tornadoes, significant severe
wind gusts, and large hail to very large hail will be possible
across a broad area from north Texas northeastward to the southern
Great Lakes.

...OH/MS Valleys through tonight...
In response to an ejecting midlevel trough and associated 110 kt 500
mb jet streak, a surface cyclone will develop northeastward from IA
to Lake Superior. Severe storms are ongoing in a broken band from
west central IL across MO into northwest AR/eastern OK, which
demarcates the effective frontal zone and focus for additional storm development through the afternoon. The warm sector in advance of
these storms is characterized by boundary-layer dewpoints in the
low-mid 60s across IL/MO and near 70 F from the Ark-La-Tex into the Ark-La-Miss. Low-level moisture will continue to spread northward
through the day on 50-70 kt flow 1-2 km above ground level, and
surface heating in cloud breaks will boost MLCAPE into the 2000-3000
J/kg range with only weak convective inhibition through the
afternoon. The northern extent of the surface warm sector
(northeast IL across northern IN/northwest OH/southern Lower MI)
will be modulated by ongoing convection.

The primary jet streak/cyclone will be displaced northwest of the
unstable warm sector, though flow will remain strong in the warm
sector with long hodographs and substantial low-level
shear/hodograph curvature. Convective mode is expected to be
somewhat messy with embedded supercells within an increasingly
extensive band of storms through the afternoon/evening. Convective
inhibition will be sufficiently weak to support some potential for a
few supercells ahead of the band in the open warm sector. The
tornado threat will be maximized for the more discrete storms within
or ahead of the main band, where a few intense (EF3+) tornadoes will
be possible. Otherwise, evolution into an extensive squall line is
expected with an accompanying threat for damaging winds (60-80 mph)
and occasional large hail (1.5-2.5 inches in diameter - especially
with persistent supercells).

Overnight, the northern portion of the squall line will eventually
move east of the more unstable warm sector and weaken from OH into
western PA. The southern portion of the convective band is expected
to pivot gradually to a more WSW-ENE orientation favoring training
convection along and atop the conglomerate cold pool.

...North TX/southeast OK this evening through Thursday morning...
In the wake of the ejecting IA-Lake Superior jet streak, midlevel
flow will tend to amplify/back with time over TX, downstream of the
amplifying large-scale trough over the Southwest. This will
contribute to weak cyclogenesis across northwest TX along the
residual baroclinic zone, and a strengthening warm advection regime
along/north of the boundary tonight. The open warm sector will
likely remain capped (per the warm elevated mixed layer observed
this morning over TX), but the environment will favor elevated
supercells to the cool side of the boundary. Very large hail in
excess of 2 inches in diameter and isolated severe gusts will be the
main threats with these elevated storms overnight.

..Thompson/Jirak.. 04/02/2025

$$
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ACUS01 KWNS 021958
SWODY1
SPC AC 021957

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Wed Apr 02 2025

Valid 022000Z - 031200Z

...THERE IS A HIGH RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO
EARLY TONIGHT FROM EASTERN ARKANSAS/NORTHWEST MISSISSIPPI TO THE
LOWER OH VALLEY...

...SUMMARY...
A tornado outbreak is expected this afternoon into early tonight
from parts of the lower Mississippi Valley into the Mid-South and
lower Ohio Valley. Numerous tornadoes, along with multiple EF3+
tornadoes, appear likely. In addition, tornadoes, significant severe
wind gusts, and large hail to very large hail will be possible
across a broad area from north Texas northeastward to the southern
Great Lakes.

...Mid-South to the OH Valley through tonight...
Convection is intensifying within a band from western AR into
southern MO, and additional storm development is likely this
afternoon farther northeast into IL. Multiple, embedded supercells
are developing within this band, and the threat for tornadoes, large
hail and damaging winds will increase through the afternoon and into
the evening as the storms spread into a more favorable downstream
environment. Warm sector supercell development appears to be
underway across southeast AR/northwest MS, and more development
could occur farther northeast into the lower OH Valley. A special
18z LZK special sounding revealed substantial moistening/ascent in
the 850-700 mb layer since 12z and additional weakening of the cap
from below is expected the remainder of the afternoon. Continued
moistening from the south and strong low-level shear through late
evening will support the potential for strong-intense (EF2-EF3+) and
long track tornadoes with any sustained warm sector supercells.

Convection is still expected to evolve into a more extensive squall
line late this afternoon into early tonight, with the potential to
produce widespread damaging winds of 65-85 mph into the OH Valley.
Tornadoes, some strong, will be possible with embedded circulations,
and especially with any discrete supercells ahead of the line this
evening into IN and vicinity. The damaging-wind threat will persist
across much of OH before weakening late tonight across eastern
OH/western PA.

...North TX early Thursday...
With amplification of the large-scale trough over the Southwest, the
surface boundary across central TX is expected to stall this evening
and return north/northwestward as a warm front late tonight in
response to weak cyclogenesis and a strenthening warm advection
regime. The pattern will become favorable for elevated supercells
on the immediate cool side of the boundary, with an accompanying
threat for very large hail (near 2.5 inches in diameter) and
isolated wind damage from 06-12z.

..Thompson.. 04/02/2025

.PREV DISCUSSION... /ISSUED 1126 AM CDT Wed Apr 02 2025/

...OH/MS Valleys through tonight...
In response to an ejecting midlevel trough and associated 110 kt 500
mb jet streak, a surface cyclone will develop northeastward from IA
to Lake Superior. Severe storms are ongoing in a broken band from
west central IL across MO into northwest AR/eastern OK, which
demarcates the effective frontal zone and focus for additional storm development through the afternoon. The warm sector in advance of
these storms is characterized by boundary-layer dewpoints in the
low-mid 60s across IL/MO and near 70 F from the Ark-La-Tex into the Ark-La-Miss. Low-level moisture will continue to spread northward
through the day on 50-70 kt flow 1-2 km above ground level, and
surface heating in cloud breaks will boost MLCAPE into the 2000-3000
J/kg range with only weak convective inhibition through the
afternoon. The northern extent of the surface warm sector
(northeast IL across northern IN/northwest OH/southern Lower MI)
will be modulated by ongoing convection.

The primary jet streak/cyclone will be displaced northwest of the
unstable warm sector, though flow will remain strong in the warm
sector with long hodographs and substantial low-level
shear/hodograph curvature. Convective mode is expected to be
somewhat messy with embedded supercells within an increasingly
extensive band of storms through the afternoon/evening. Convective
inhibition will be sufficiently weak to support some potential for a
few supercells ahead of the band in the open warm sector. The
tornado threat will be maximized for the more discrete storms within
or ahead of the main band, where a few intense (EF3+) tornadoes will
be possible. Otherwise, evolution into an extensive squall line is
expected with an accompanying threat for damaging winds (60-80 mph)
and occasional large hail (1.5-2.5 inches in diameter - especially
with persistent supercells).

Overnight, the northern portion of the squall line will eventually
move east of the more unstable warm sector and weaken from OH into
western PA. The southern portion of the convective band is expected
to pivot gradually to a more WSW-ENE orientation favoring training
convection along and atop the conglomerate cold pool.

...North TX/southeast OK this evening through Thursday morning...
In the wake of the ejecting IA-Lake Superior jet streak, midlevel
flow will tend to amplify/back with time over TX, downstream of the
amplifying large-scale trough over the Southwest. This will
contribute to weak cyclogenesis across northwest TX along the
residual baroclinic zone, and a strengthening warm advection regime
along/north of the boundary tonight. The open warm sector will
likely remain capped (per the warm elevated mixed layer observed
this morning over TX), but the environment will favor elevated
supercells to the cool side of the boundary. Very large hail in
excess of 2 inches in diameter and isolated severe gusts will be the
main threats with these elevated storms overnight.

$$
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