ACUS01 KWNS 111300
SWODY1
SPC AC 111258

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0758 AM CDT Thu Jun 11 2026

Valid 111300Z - 121200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
IOWA AND NORTHERN ILLINOIS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHEAST/MID-ATLANTIC STATES...

...SUMMARY...
Widespread severe thunderstorms are expected across parts of the
Midwest and Great Lakes region, including Iowa, northern Missouri,
northern Illinois and southern Wisconsin to Lower Michigan and
northern Indiana. This includes the potential for widespread/intense
damaging winds, large hail, and tornadoes, some of which may be strong.

...Midwest/Great Lakes...

Portions of the region have been upgraded to a Moderate Risk.
Another very active day with widespread/intense severe storms is
expected regionally. A consequential severe risk is already ongoing
this morning across Iowa/far northern Missouri, and will continue east-northeastward and become more prominent regionally during the
day. A well-organized/eastward-accelerating bowing cluster of
storms, now supported by an apparent MCV, has had a history of
measured severe-caliber wind gusts overnight and in the predawn
hours from southeast Nebraska into southern Iowa. A similar severe
risk should continue east-northeastward through midday across
eastern Iowa/far northeast Missouri toward northern Illinois, with
more of a surface-based/tornado risk potentially unfolding
relatively early today aside from a continued prominent damaging wind threat.

Scenario is supported by a robust southwesterly low-level
jet/moisture transport, even with some diurnal weakening of the
low-level jet possible. Also influential is a prominent/increasingly neutral-tilt-shortwave trough and jet streak crossing the Corn Belt,
notably strong features by mid-June standards.

Convective overturning/outflow from last evening's MCS are still
residual factors evident this morning in observational
data/supplemental 3D mesoanalysis across far eastern Iowa, far
northeast Missouri into central Illinois. This is sampled by the 12z
observed sounding from KILX/Lincoln, IL. These residual factors may
somewhat southward-focus the peak/most-intense severe weather later
today, with more uncertainty progressively northward in general
proximity to Lake Michigan latitudinally, including parts of Wisconsin/Michigan. The timing/residual impacts of this morning's
MCS across Iowa/northern Missouri into northern Illinois and severe
potential in its wake near the surface low and front, and/or to its
(MCS) north-northeast are a bit less uncertain. That said, mass
response/fluxes related to the dynamic shortwave trough/speed max
will be notable and consistent with heightened severe-potential even
if outflow/cloud debris exists and sub-regional areas of
destabilization are sub-optimal.

Details of later-afternoon severe potential is somewhat contingent
on how the morning MCS further evolves, but a window for
redevelopment in its immediate wake will probably exist. This will
lead to a renewed round of severe storms as development occurs near
the cold front, and perhaps preferentially favors prior outflow,
with a damaging wind and tornado risk continuing eastward this
evening as the low-level jet re=intensifies and as storms gradually
grow upscale toward Lake Michigan and across Illinois/Indiana/Lower Michigan.

...Eastern Kansas and Southern Plains...

Additional thunderstorm development is expected along the trailing
cold front into portions of the central/southern Plains. Deep layer
shear will be maximized in the post-frontal environment; however,
around 20-30 kt of effective bulk shear and moderate to strong
instability will support some supercell structures capable of large
hail and damaging winds. Storm motions and boundary parallel shear
will likely lead to clustering and messy modes over time.

...Mid-Atlantic ad central Appalachians...
Forcing for ascent from multiple shortwave disturbances across the
northeast and dewpoints in the 60s to 70s F will support development
of widely scattered thunderstorms by afternoon across the
Mid-Atlantic into the central Appalachians. Though vertical shear
will be generally weak, moderate to strong instability will be in
place will support stronger updrafts capable of damaging winds. It
is likely that several clusters will emerge with potential for
organizing along cold pools and more focused corridors of damaging
wind potential.

..Guyer/Wendt.. 06/11/2026

$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/10)

ACUS01 KWNS 171301
SWODY1
SPC AC 171259

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 AM CDT Wed Jun 17 2026

Valid 171300Z - 181200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS ILLINOIS
AND INDIANA...

...SUMMARY...
An outbreak of severe thunderstorms is expected today into tonight,
with the peak threat centered over Illinois and Indiana. Several
intense tornadoes, swaths of damaging gusts over 75 mph and damaging wind-driven large hail will all be possible.

...Midwest including Illinois/Indiana/Missouri/Ohio...

A very active/potentially dangerous day is expected today into
tonight, although some sub-regional forecast details remain a bit
uncertain. This is largely attributable to an upscale-growing
intense MCS which has been evolving in the predawn hours across
central/eastern Iowa, moving south of the I-80 corridor as of 730am
CDT. Measured significant wind gusts in excess of 80 mph have been
observed before sunrise, including a measured 94 mph measured wind
gust in Marshall County, Iowa.

This intense and increasingly well-organized MCS will continue to be
influenced by an extremely strong southwesterly jet of 70 kt and
robust warm advection/moisture transport, and likely continue
southeastward from southeast Iowa into north-central/west-central
Illinois. This will likely include an increasing potential for
surface-based storms and an appreciable uptick in damaging
wind/tornado potential early today, especially on the
south-southwest flank of the MCS in closer proximity to the northeastward-shifting warm front.

Ahead of this early activity, a warm front will push
north-northeastward across Indiana/Ohio. New severe storm
development, perhaps MCV-influenced and transitioning out of the
remnant activity and/or forming near the warm front, is possible
across Indiana into Ohio. Shear profiles will be excessive, with
tornado risk only conditional on minimal instability being present.
The result may be a isolated tornadic supercells. The warm frontal
position will need to be monitored northward toward the
Indiana/Michigan border vicinity. Even if instability is elevated
into Michigan, extreme shear and lift may still yield damaging winds
and even a tornado risk.

To the west, rapid air mass recovery is expected on the
west-southwestern flank of the early day MCS from Missouri into central/possibly parts of northern Illinois, even where appreciable
early day MCS impacts occur early. This recovery will be fueled by
mid-June insolation/moisture content and robust advection, again
attributable to atypically robust (50-65 kt) low/mid-tropospheric west-southwesterly flow by mid-June/diurnal standards. In the
presence of 65-70 F surface dewpoints, this will likely result in a
corridor of 2000-3500 J/kg MLCAPE.

This will likely set the stage for the development of a broken line
of intense supercells, potentially favoring prior outflow (or
outflow-augmented warm front) and post-MCS recovery zone of
differential heating across Illinois and perhaps eventually into
western Indiana. Given the clearly supercellular shear profiles and
ample venting aloft, linear storm mode is unlikely for most of the
event. Long-tracked supercells producing tornadoes and damaging
large hail are likely. Some strong to potentially intense tornadoes
are plausible given the magnitude of the low/mid-tropospheric flow,
and again potentially heightened in vicinity of the prior
outflow/warm front. Some damaging wind threat will likely also
increase by evening as storms continue across Indiana into Ohio and
potentially southward toward the Ohio River.

...Upper Texas Coast/Middle Gulf Coast...

The NHC forecast shows Potential Tropical Cyclone One moving into
southwest Louisiana by this evening. Wind fields associated with
this system will strengthen out of the south ahead of it, resulting
in areas of strong low-level shear from the upper Texas coast across
southern portions of Louisiana and eventually into southern
Mississippi. Mid to upper 70 F dewpoints will contribute to modest
CAPE values, supporting embedded stronger cells with tornadic potential.

..Guyer/Broyles.. 06/17/2026

$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/10)