SPC Apr 28, 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 Tue Apr 28 2026

Valid 281200Z - 291200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
NORTHERN TEXAS INTO THE LOWER MISSISSIPPI VALLEY...

...SUMMARY...
Multiple rounds of strong to severe thunderstorms are likely across
parts Texas into the lower Mississippi and Tennessee Valleys this
afternoon and evening. Very large hail, swaths of damaging wind, and
a few tornadoes are possible.

...Synopsis...
A series of mid-level troughs, embedded within a broader
low-amplitude mid-level flow regime, will traverse the central U.S.
today. A surface low and associated cold front will continue to
progress across the OH Valley toward the East Coast during the day.
However, the approach of another mid-level trough over the Ozark
Valley region will encourage either a weak surface low or surface
trough to develop over central TX. This will stall the southward
progression of the surface cold front given appreciable low-level
warm-air/moisture advection. Seasonally cold air aloft and
accompanying upper support from multiple embedded mid-level
perturbations will overspread the warm-air advection regime,
supporting several rounds of thunderstorms. Given strong vertical
wind shear over the warm sector, severe storms are likely,
especially over portions of the southern Plains toward the TN
Valley.

...Portions of northern TX into the TN Valley...
A complex severe weather scenario is expected across TX into the TN
Valley through the period, with multiple rounds of severe
thunderstorms likely. The first round of storms is currently
initiating over western TX, and may increase in coverage between
12-18Z across central OK into northern TX as a lead mid-level
impulse traverses a WAA regime. 7-8 C/km mid-level lapse rates amid
50+ kts of effective bulk shear will support elevated multicells
capable of producing severe hail. These storms will progress across
the MS Valley through the day. Some guidance indicates that these
storms may evolve into an MCS by afternoon, accompanied by a
damaging gust threat over the Gulf coast states.

Regardless of the evolution of earlier storms, guidance consensus
depicts adequate clearing behind this initial wave over TX into the
Ozark Valley region. Strong surface heating will encourage surface
temperatures to reach 90 F in some locales, amid 70+ F surface
dewpoints. Given 8-9 C/km mid-level lapse rates, MLCAPE should reach
the 2500-4000 J/kg range by mid to late afternoon. By this time, the
primary mid-level trough will overspread the southern Plains,
promoting enough deep-layer ascent for another round of storms to
initiate. Given 50 kts of effective bulk shear and initially
straight hodographs, supercells are expected, accompanied by a
severe hail threat. The most intense supercells may develop over
northern TX and progress eastward, and will be capable of producing
severe hail as large as 3-4 inches in diameter. Given a lingering
low-level jet (supporting elongated hodographs with some low-level
curvature) over the Sabine River Valley, a few dominant/right-moving
supercells may produce a few tornadoes, though the tornado threat
will be conditional on adequate boundary-layer
mixing/destabilization. Later in the afternoon/early evening, severe
hail/isolated tornado producing supercells may merge into an MCS,
accompanied by a severe wind threat across the Lower MS Valley.

...Portions of central into southern TX...
Forcing for ascent will be weak across portions of central into
southwestern TX. Nonetheless, 8-9 C/km mid-level lapse rates will
overspread a well-mixed boundary layer. Tropospheric speed shear
exceeding 40 kts will yield elongated hodographs, so any storm that
can initiate, mature, and sustain itself should be supercellular in
nature, accompanied by a severe hail threat. Any instance of hail
with these storms may include stones exceeding 2 inches in diameter.
Since a second, low-amplitude mid-level impulse will overspread
western and central TX toward the end of the period, isolated
supercell initiation will be possible across portions of central
into southwestern TX late this afternoon into early (12Z) Wednesday
morning.

..Squitieri/Moore.. 04/28/2026


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SPC Apr 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
0759 PM CDT Mon Apr 27 2026

Valid 280100Z - 281200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
SOUTHEASTERN MISSOURI INTO FAR SOUTHERN ILLINOIS AND WESTERN
KENTUCKY...

...SUMMARY...
Severe storms should continue through tonight with a wind and hail
threat. A few tornadoes may still occur, and a couple of strong
tornadoes remain possible.

...Synopsis...
A negatively tilted 500 mb mid-level trough continues to traverse
the Upper Midwest in tandem with a surface low, supporting a surface
cold front to sweep across the Mid-MS Valley. A persistent elongated
convective system has materialized along the cold front, accompanied
by several embedded and preceding supercells. These storms have a
collective history of severe wind and hail, with some stones
reaching the 2-3 inch diameter range.

Upper 60s to low 70s F surface dewpoints, beneath 8+ C/km mid-level
lapse rates, resides ahead of the cold front/storms, yielding over
3000 J/kg MLCAPE in spots. Meanwhile, strong mid-level flow
associated with a speed max is overspreading an intensifying (45+
kt) southwesterly low-level jet, resulting in 50+ kts of effective
bulk shear and large/curved low-level hodographs with 300-500 m2/s2
effective SRH (per 00Z mesoanalysis and regional VADs). Supercells
have failed to organize and produce tornadoes up to this point.
However, storms along/ahead of the cold front will continue to
advance eastward toward the low-level jet/shear axis. Therefore, an
uptick in tornado activity may still occur early tonight, especially
with any discrete, sustained supercells that can develop. Discrete
storms may also be accompanied by severe hail, with severe wind
gusts likely with continued linear storm modes.

..Squitieri.. 04/28/2026


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SPC Apr 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
0249 PM CDT Mon Apr 27 2026

Valid 272000Z - 281200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS
EAST/SOUTHEAST MISSOURI...SOUTHERN ILLINOIS...WESTERN KENTUCKY...AND
NORTHWEST TENNESSEE...

...SUMMARY...
Numerous severe thunderstorms are expected from the mid
Mississippi/lower Ohio Valleys into the Mid-South through this
evening, with a threat for multiple strong to intense tornadoes
(EF3+), widespread severe/damaging wind gusts, and scattered large
to very large hail.

...20z Update...
Only minor adjustments were made to extend the Marginal Risk back
into southeastern Kansas/northeastern Oklahoma to account for storms
initiating over the last hour.

The Moderate Risk remains unchanged with this update. The morning
MCS is now moving through eastern Illinois/southern Indiana. Further
west in Missouri and western Illinois, modifying remnant outflow
remains near the St. Louis Metro. Cumulus south of this boundary
across southeastern Missouri into southern Illinois, cumulus within
the warm sector is deepening. Increasing MLCAPE/steepening lapse
rates are nosing northward in southern central Missouri and
south-central Illinois.

Just to the west of the Mississippi River, radar shows occasional
attempts at initiation within the open warm sector. While the
details continue to evolve, it likely that a corridor of conditional
threat for strong-intense tornadoes will develop from the Missouri
Bootheel into southern Illinois/western Kentucky. Within this region
strong daytime heating has led to a volatile air mass, with moderate
to strong MLCAPE 2000-3000 J/kg and strong deep layer shear. VAD
profiles frm PAH (Paducah, KY) and LSX (St. Louis, MO) indicate a
rich SRH environment of around 200-300 m2/s2 in the 0-1 km layer. It
is likely that supercells capable of all hazards, including
strong-intense tornadoes, large to very large hail, and damaging
winds. Will develop across this region soon. See MCD571 for
additional information.

The conditional threat for strong tornadoes will extend as far south
as the Arklatex into portions of western Tennessee. Through time,
storm mode will shift to become linear with the southward moving
front, which will bring an increase into the evening of damaging
wind threat. Line embedded tornadoes, some of which may be strong,
will continue to be a threat into the evening.

..Thornton.. 04/27/2026

.PREV DISCUSSION... /ISSUED 1150 AM CDT Mon Apr 27 2026/

...Mid Mississippi Valley/Midwest into the Mid-South/Lower
Mississippi Valley...
Forecast scenario largely unchanged in that a very active
severe-weather/tornado day is expected regionally, especially into
late afternoon and this evening. Initially, a relatively long-lived
linear cluster of convection persists at late morning across
east-central/south-central Illinois, with additional initially
elevated storms on its eastern/southern periphery, moving from
eastern Illinois into Indiana, with severe hail and damaging winds
persisting as early day hazards.

Over time, air mass will continue to moisten and rapidly destabilize
along/south of the MCS-associated outflow from central Missouri into
south-central Illinois. A mid/upper-level trough will eject
northeastward from the northern/central Plains into the Midwest and
middle Mississippi Valley through the period. Low-level mass
response will encourage the primary surface low to consolidate
across Minnesota/Wisconsin by this evening, with a warm front
effectively delineated by the morning convection.

Strengthening west-southwesterly flow aloft associated with a 50-70
kt mid-level jet will overspread much of the warm sector by peak
heating, and a 35-45 kt south-southwesterly low-level jet will both
provide ample low-level and deep-layer shear to support supercells.
Initially discrete surface-based development appears likely to occur
into mid-afternoon across the mid Mississippi Valley/Mid-South ahead
of the surface cold front, and perhaps along weak low-level
confluence zones in the open warm sector including generally near
the confluence of the Mississippi/Ohio Rivers southward into the
Mid-South.

These supercells will exist in a very favorable environment for
tornadoes through the afternoon and evening, and multiple strong to
intense tornadoes (EF2/3+) appear likely, especially from parts of
Missouri into Illinois along/near the effective front. This strong
tornado potential will also likely extend farther south within the
warm sector into the Mid-South.

By early evening, convection will probably tend to consolidate into
clusters of supercells and then more linear segments with some
increase in damaging wind potential aside from large hail and a
continued multi-mode tornado risk tonight.

...ArkLaTex into Texas...
While storm coverage may trend lesser with southwest extent, the
potential for at least isolated intense storms will exist across the
region. Supercells capable of producing large to very large hail and
occasional damaging winds are expected. Increasing low-level
warm/moist advection tonight could foster additional robust
thunderstorms along the retreating dryline and eventually the
southward-moving cold front.


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SPC Apr 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
0745 AM CDT Mon Apr 27 2026

Valid 271300Z - 281200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
MISSOURI INTO ILLINOIS...

...SUMMARY...
Numerous severe thunderstorms are expected from the mid
Mississippi/lower Ohio Valleys into the Mid-South through this
evening, with a threat for multiple strong to intense tornadoes
(EF-3+), widespread severe/damaging wind gusts, and scattered large
to very large hail.

...Mid Mississippi Valley/Midwest into the Mid-South/Lower
Mississippi Valley...
An active severe weather day is forecast for much of the mid MS
Valley/lower OH Valleys into the Mid-South. Ongoing thunderstorms
this morning complicate the overall scenario to some extent, but a
very favorable corridor for intense supercells and strong tornadoes
is apparent this afternoon/evening across parts of MO into IL, where
a Moderate Risk (Level 4 of 5) has been introduced.

Elevated supercells with mainly a hail threat should persist for at
least a couple more hours this morning across the mid MS Valley as
strong low-level warm advection aids in continued influx of
sufficient MUCAPE amid strong deep-layer shear. Multiple
clusters/embedded supercells are also ongoing this morning across
western into northern MO. This activity should pose a greater threat
for scattered severe/damaging winds, along with some hail risk. The
tornado threat in the short term (this morning) remains unclear, but
it should eventually increase as the boundary-layer across central
MO continues to gradually destabilize/moisten. See Mesoscale
Discussion 565 for more details on the near-term severe risk with
these ongoing thunderstorms.

Current expectations are for the greatest severe risk to focus south
of these morning thunderstorms. A mid/upper-level trough will eject
northeastward from the northern/central Plains into the Midwest and
mid MS Valley through the period. Low-level mass response will
encourage the primary surface low to consolidate across MN/WI by
this evening, with an effective warm front delineated by the morning
convection. Aided by daytime heating and steep mid-level lapse
rates, a moderately to strongly unstable airmass is expected to be
in place by early to mid afternoon across much of central
MO/southern IL southward into the Mid-South and lower MS Valley.

Strengthening west-southwesterly flow aloft associated with a 50-70
kt mid-level jet will overspread much of the warm sector by peak
heating, and a 35-45 kt south-southwesterly low-level jet will both
provide ample low-level and deep-layer shear to support supercells.
Initially discrete surface-based development appears likely to occur
by 19-21Z across the mid MS Valley/Mid-South ahead of the surface
cold front, and perhaps along weak low-level confluence zones in the
open warm sector.

These supercells will exist in a very favorable environment for
tornadoes through the afternoon and evening, and multiple strong to
intense tornadoes (EF-2/3+) appear likely, especially from parts of
MO into IL along/near the effective front. This strong tornado
threat may also extend farther south into AR/TN, but confidence is
somewhat lower with southward extent due to weaker large-scale
forcing. Large to very large hail (2-3 inches in diameter) may also
occur with any sustained supercells.

By early evening, convection will probably tend to consolidate into
clusters capable of producing numerous to widespread damaging winds
from the mid MS Valley eastward into the lower OH Valley, before
eventually weakening tonight as instability gradually decreases. A
threat for QLCS and embedded supercell tornadoes will persist
through much of the evening and early overnight hours as well given
strong low-level shear forecast.

To the north of the ongoing morning convection across IA/northern
IL/WI, a lesser (but non-zero) severe risk is forecast. This region
will have less instability this afternoon, but strong shear. Have
maintained the Marginal/Slight Risks for the possibility of isolated
to locally scattered hail/damaging winds, and perhaps a couple of
tornadoes.

...ArkLaTex into Texas...
Confidence in sustained convection occurring from the ArkLaTex
southward into TX is lower compared to locations farther north. But,
strong heating ahead of a surface dryline could support isolated to
scattered supercells capable of producing large to very large hail
and occasional damaging winds. Increasing low-level warm/moist
advection tonight could foster additional robust thunderstorms along
the retreating dryline and eventually the southward-moving cold
front. Severe probabilities have been expanded across these regions
to account for this potential.

..Gleason/Thornton.. 04/27/2026


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