ACUS02 KWNS 160600
SWODY2
SPC AC 160559

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Tue Jun 16 2026

Valid 171200Z - 181200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF CENTRAL ILLINOIS INTO NORTHWEST INDIANA...

...SUMMARY...
An outbreak of severe thunderstorms is expected across portions of
Illinois and Indiana on Wednesday. Intense tornadoes, swaths of
damaging gusts to 80 mph and hail to 2.5 inch diameter are expected.

...Midwest...

A volatile environment for severe thunderstorms is expected to
develop across portions of the Midwest from IA/MO into IL/IN/OH on
Wednesday, with significant all-hazards severe expected.

A mid/upper level shortwave trough initially over the northern
Plains early Wednesday will pivot southeast across the Upper Midwest
through 00z, and much of the Great Lakes by 12z Thursday. As this
occurs, particularly intense mid and upper level flow, especially by
June standards, if forecast to increase over the region. A 60-80 kt
westerly 500 mb jet stream will overspread much of the Midwest
through the evening, before increasing further during the nighttime
hours. Furthermore, an impressive southwesterly 850 mb low-level jet
around 50-60 kt will be oriented from KS into IA at 12z. This
feature will spread east/northeast across IL/IN/OH through evening. Interestingly, the core of the low-level jet may be somewhat
displaced to the east of the core warm sector expected to develop
across the Mid-MS Valley vicinity, perhaps tied to an early-day
shortwave impulse ejecting across IA/IL during the morning.
Nevertheless, 40-55 kt 850 mb winds will persist even across the
warm sector even as the core of the low-level jet overspreads the
Ohio Valley toward Lower MI during the afternoon.

At the surface, an elongated area of low pressure will extend from
ND to the Mid-MO valley Wednesday morning. A warm front will extend
from northwest IA southeastward across central IL, while a cold
front extend from eastern NE into western KS. As this system
progresses east through the day, the warm front will lift northward
into northern IL/IN/OH and upper 60s/near 70 dewpoints are expected.
Aided by steep midlevel lapse rates/cooling aloft, MLCAPE will
approach 2500-3500 J/kg. The latitude of the warm front continues to
be a point of uncertainty. Most forecast guidance depicts morning
convection near and north of the warm front within a strong warm
advection regime moving eastward across IA/northern IL/IN. It is
uncertain if this will suppress the northward advancement of the
warm front. The ultimate position of the warm front will have large
impacts on where particularly concerning strong to intense tornado
potential may eventually develop as storm motion would likely be
along the boundary, rather than across the boundary, allowing for
potentially fast-moving/long-track supercells interacting with the
warm front and remaining within the favorable warm sector.

As the surface cold front develops east, additional convection will
develop along the boundary by late afternoon/early evening from far
southeast IA into northern MO and eastern KS. Initial supercells
along this boundary will pose an all hazards risk -- including very
large hail, strong tornadoes and damaging gusts. With time, this
convection may develop into a line propagating east/southeast. If a
linear MCS develops, swaths of damaging wind gusts will be possible.


In general, given the strength of background flow fields, damaging
wind potential could be significant regardless of storm mode.
Furthermore, even storms developing north of the warm front could
still produce severe gusts given large MUCAPE, fast storm motion and
intense flow just above the surface. Favorable low-level shear will
also support continued tornado potential even within a linear storm
mode via embedded supercell structures and mesovortex generation.
Large to very large hail potential is most likely early in storm
development and where supercells are more likely to remain discrete
(northern MO/far southeast IA/north-central IL).

...Gulf Coast...

Isolated strong gusts are possible in association with a tropical
disturbance moving eastward along the Gulf Coast. See the tropical
weather outlook from the National Hurricane Center for more
information.

..Leitman.. 06/16/2026

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