ACUS01 KWNS 210556

SWODY1

SPC AC 210554



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

1254 AM CDT Sun Jun 21 2026



Valid 211200Z - 221200Z



...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE

CENTRAL/SOUTHERN PLAINS INTO THE OZARKS AND OHIO VALLEY...



...SUMMARY...

Severe storms are possible from the central High Plains into the

Ohio Valley, mainly this afternoon into tonight. Large to very large

hail, severe winds, and tornadoes will be possible. Some

strong-tornado potential could develop across parts of Missouri,

Illinois, and Indiana during the afternoon and early evening.



...Parts of MO into the Ohio Valley...

An all-hazards severe threat, including some conditional

strong-tornado potential, is still evident from parts of MO into the

Ohio Valley later today, though uncertainty remains regarding the

magnitude and most favored corridor of the greatest threat. No

upgrade was made with this outlook, though greater tornado and/or

wind probabilities may eventually be needed, depending on how the

uncertainties are resolved. 



Guidance generally suggests that an MCV currently evolving across KS

will move across central/northern MO through the morning, before

moving into parts of the Midwest and Ohio Valley through the

afternoon. In association with the MCV, a surface low may deepen

along a front and move across parts of central MO/IL. Guidance

varies regarding the strength of the surface low, enhancement to

low-level shear/SRH, and magnitude of destabilization in advance of

the MCV. However, in general, rich moisture and enlarged low-level

hodographs will support development of a storm cluster with embedded

supercells and/or mesovortices, if sufficient diurnal

destabilization occurs. Tornadoes and damaging winds could accompany

any organized cells/clusters. Strong-tornado potential could evolve

if any supercells can be sustained within this regime. 



In the wake of the MCV, relatively strong heating will support at

least moderate destabilization along the trailing front across parts

of central/southern MO. While some weakening/veering of low-level

flow is expected after the passage of the MCV, deep-layer shear will

remain sufficient for organized development along the boundary,

which could pose an all-hazards severe threat from late afternoon

into the evening from south-central MO into the lower OH Valley. 



...Central High Plains into the Ozarks...

A mid/upper-level shortwave trough initially over WY will move

toward KS/NE later today. A 35-50 kt midlevel jet maximum attendant

to this shortwave will impinge upon parts of the central and

southern High Plains. An outflow-influenced front will likely extend

across parts of southern KS, with moist easterly flow expected north

of this boundary by late afternoon, while strong heating will occur

south of the boundary. Scattered afternoon storm development is

expected within the post-frontal regime from southeast WY/northeast

CO into western NE/KS. Moderate buoyancy and favorable deep-layer

shear will support supercell development, with a threat of large to

very large hail, localized severe gusts, and possibly a tornado. 



Widely scattered afternoon storm development will also be possible

in the vicinity of the surface front, from northwest OK into

southeast KS/southwest MO. Moderate to strong buoyancy and

sufficient deep-layer shear will support supercell development with

initial storms along the front, with some clustering possible later

in the convective evolution. Large to very large hail, damaging

winds, and some tornado potential could accompany the strongest

afternoon/evening storms. 



Late tonight into early Monday morning, guidance generally suggests

development of one or more upscale growing clusters, evolving from

either diurnal convection, or nocturnal elevated redevelopment.

Swaths of strong to severe gusts could accompany any upscale growth,

though guidance varies considerably regarding the most favorable

corridors late in the forecast period.



..Dean/Squitieri.. 06/21/2026



$$