ACUS02 KWNS 170602
SWODY2
SPC AC 170600

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Sun May 17 2026

Valid 181200Z - 191200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS PORTIONS OF
CENTRAL AND NORTHEASTERN KANSAS INTO FAR SOUTHEASTERN NEBRASKA...

...SUMMARY...
Numerous severe thunderstorms are expected to develop Monday along a
cold front and dryline extending from the Great Lakes into the
central/southern Plains. Supercells capable of all hazards
(including very large hail and strong to intense tornadoes) will
likely occur across central Kansas into southeastern Nebraska.

...Synopsis...
On Monday, a mid-level trough will deepen and lift out of the Four
Corners into the central Plains as a belt of enhanced westerly flow
moves within the mean flow. As this westerly flow overspreads the
Rockies, deepening of a surface cyclone across eastern Colorado is
expected, with strengthening of southerly surface flow across the southern/central Plains. Convection is likely to be ongoing in the
vicinity of a lead shortwave across portions of Iowa into Wisconsin
at the start of the D2/Monday period.

A front will extend from the surface low in eastern Colorado
northward across southeast NE/IA/WI. A surface dryline will be
located across central Kansas extending southward into western
Oklahoma and southwestern Texas. Mid 60s to 70s dew points will be
common east of the dryline and northward ahead of the cold front
into the Great Lakes. Numerous severe thunderstorms are expected to
develop along the cold front southward to the dryline by the
afternoon. A corridor of enhanced severe potential will exist across
central KS/southeastern NE/southwest IA/northwest MO.

...Central KS into southeast NE/southwest IA/northwest MO...

Near the triple point of the surface low/dryline/cold front across
central Kansas, a more favorable corridor of severe potential will
exist Monday afternoon. Morning cloud cover should erode across
central Kansas by the afternoon allowing for strong daytime heating
and warming. Temperatures ahead of the dryline will approach the mid
to upper 80s, with dew points in the upper 60s to 70s. This will
yield and axis of moderate to strong MLCAPE around 3500-4500 J/kg
extending from central Kansas into southeastern Nebraska. MLCIN will
erode through the afternoon by around 18-20z with initiation
expected along the dryline and cold front to the north by around
20-21z. Forecast soundings indicate favorable kinematics to support
organized supercells, given deep layer shear around 40-50 kts.
Initial supercells will be capable of large to giant hail (2-4+
inch) given steep low to mid-level lapse rates around 7-8 C/km. Hail probabilities were increased with this outlook to support this potential.

The southerly low-level jet is progged to increase as large scale
ascent spreads eastward through the afternoon, peaking around 40-50
kts by the 00-03z across northern OK into central KS. Strengthening
flow in the 850-700 mb layer will elongate low-level hodographs with
broad clockwise curvature in the 0-2 km layer and rapidly increasing
low-level SRH. Forecast soundings indicate 0-1 km SRH will approach
250-300 m2/s2 across portions of central/eastern KS. This in
combination with the volatile thermodynamic environment will support
an increase in tornado potential through the evening. Should
discrete supercells be maintained, strong to intense tornadoes will
be possible primarily from central to northeastern KS into
southeastern NE. Given southwesterly deep layer shear is oriented
somewhat parallel to the southwest to northeast cold front, storms
near the front may cluster and grow upscale. Better potential exists
for a more semi-discrete supercell across central Kansas ahead of
the dryline. A few HREF members do support potential for this
scenario, with long UH tracks across KS into southern Nebraska.
Tornado probabilities were increased from east-central KS into
southeastern NE/southern IA/northwestern MS.

...Central IA into portions of IL/KY/WI/IN/Lower MI...

Elevated thunderstorm activity will be likely at the beginning of
the period across portions of Iowa/Wisconsin. This will pose some
risk for a few instances of severe hail. Guidance suggests that
recovery will occur by the afternoon across this region with
thunderstorms redeveloping along the cold front and re-intensifying
of downstream convection the into the afternoon. Initial morning
convection may pose some wind/hail risk into IL/IN/western KY.
Additional development by the evening along the cold front to the
north will pose some wind/hail risk across portions of the upper Midwest.

...OK/TX...

A more conditional severe risk exists further south across OK/TX.
Large-scale ascent will remain weaker further south. However, strong instability within the very moist warm sector will exist. Deep layer
flow will be somewhat less compared to further north, but still
sufficient for supercells. If storms can develop, a risk for large
to very large hail and perhaps a tornado will exist.

..Thornton.. 05/17/2026

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

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)