ACUS01 KWNS 171955
SWODY1
SPC AC 171953

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0253 PM CDT Fri Apr 17 2026

Valid 172000Z - 181200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM FAR
NORTHWEST OKLAHOMA THROUGH CENTRAL AND EASTERN KANSAS INTO
WEST-CENTRAL MISSOURI...

...SUMMARY...
Numerous severe thunderstorms are likely this afternoon into tonight
across parts of the Upper Midwest southward across the lower
Missouri Valley and central/southern Great Plains. Initially this
may be accompanied by a risk for large to giant hail and a few
strong tornadoes, before severe wind gusts of 60 to 90 mph become
the most prominent hazard by this evening.

...20Z Update...
Severe probabilities have been adjusted to account for progression
of the cold front this afternoon. The remainder of the forecast is
unchanged. See MD 475 for short-term details of evolving tornado
risk along the Illinois/Wisconsin border.

..Wendt.. 04/17/2026

.PREV DISCUSSION... /ISSUED 1203 PM CDT Fri Apr 17 2026/

...Synopsis...
Recent surface analysis places a low over south-central MN, with a
cold front extending southwestward to another low over central KS. A
warm front also extends southwestward from the MN low through far
southwest MN and far northern IL into central IN. This warm front is
demarcated well by the 56 deg F isodrosotherm. Farther south, a
dryline extends from the triple point KS low back southwestward
through the TX Panhandle and into far southeast NM. A broad, moist
warm sector exists to the east of the cold front and dryline,
characterized largely by dewpoints in the low to mid 60s.

A well-defined shortwave trough is apparent on satellite imagery,
extending from southern Saskatchewan back southwestward into the
eastern Great Basin. This wave is forecast to continue eastward,
with a attendant increase in the mid-level flow across much of the
Plains and Upper/Mid MS Valley. The cold front will surge eastward/southeastward in response to this wave as well, interacting
with the warm sector to support numerous strong to severe
thunderstorms from parts of the Upper Midwest southward across the
lower Missouri Valley into southern Plains.

...Upper/Mid MS Valley...
Moderate to strong low-level moisture advection is expected across
the Upper MS Valley today as the surface low mentioned in the
synopsis progresses northeastward, with an attendant northward shift
of the warm front as well. The risk across this region may evolve in
several phases, beginning with the elevated thunderstorms currently
ongoing across northwest WI. This storms will likely continue
northeastward, posing a risk for severe hail and isolated damaging
gusts. Additional development is possible northwest of this activity
along the occluded front, with some hail possible here as well.

Farther south, the northeastward advecting low-level moisture
coupled with strong heating and steep lapse rates will result in a
strongly unstable airmass along and just south of the warm front by
the early afternoon. Storm initiation is anticipated within this
open warm sector by early afternoon, forced by a mix of warm-air
advection, low-level confluence, and subtly increasing large-scale
ascent. This activity should be ahead of the front and initially
discrete. The overall parameter space will be characterized by
strong to very strong buoyancy, moderate deep-layer vertical shear,
and strong low-level helicity. Supercells capable of all hazards are
expected, including large to very large (i.e. 3"+ hail), strong to
intense tornadoes, and severe wind gusts. Storm interactions are
expected to strongly influence the tornado risk, with the initially
discrete mode likely becoming messy quickly.

Farther west, other storms are likely to evolve quickly along the
front, developing into a band of severe thunderstorms that will push
east coincident with the front. Damaging wind gusts will tend to
become more prevalent during the evening with linear storm modes.
Some tornado risk may continue into the evening as maturing bands of
storms yield a threat for bowing segments and embedded mesovortices,
before this activity gradually diminishes late as it moves east into
IN/Lower MI late.

...KS/OK/MO...
A very unstable airmass is expected to develop along and ahead of
the triple point over south-central KS an associated cold front and
dryline. Strong low-level convergence will likely lead to initial
storm development near the triple point. This initial activity will
be supercellular and capable of very large to giant hail (over
3-3.5" in diameter). Highest coverage of very large hail is expected
over from far northwest OK into south-central KS. Strong downdrafts
(60 to 80 mph) are possible as well. With a largely
boundary-parallel orientation to the deep-layer shear, the tornado
risk appears relatively lower. However, given the supercell mode and
potential interactions with outflow, a low-probability tornado risk
remains. A more north-south configuration to the dryline supports a
conditional tornado risk into far northwest TX.

With time, upscale growth and the development of a
forward-propagating MCS is anticipated across central and eastern
KS. Very strong gusts (80+ mph) are possible with this MCS.
Additionally, some QLCS tornado risk will exist within this line as
long as it stays ahead of the surging cold front. The front will
continue sweeping southeastward, with storms along this boundary
yielding a risk for wind/hail.

$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

ACUS01 KWNS 271247
SWODY1
SPC AC 271245

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

$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)