ACUS02 KWNS 201724

SWODY2

SPC AC 201723



Day 2 Convective Outlook  

NWS Storm Prediction Center Norman OK

1223 PM CDT Sat Jun 20 2026



Valid 211200Z - 221200Z



...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL

HIGH PLAINS INTO THE OHIO VALLEY...



...SUMMARY...

Severe storms are possible along a frontal zone from the Ohio Valley

to the central High Plains from Sunday afternoon into night. Large

to very large hail, severe winds, and tornadoes (some of which could

be strong) will be possible.



...Synopsis...



A series of vorticity maxima, some with convective origins, will

translate east through the central Plains and OH Valley, along with

a belt of 40-50+ kt winds at 500 mb. In the lower levels, a

southwesterly low-level jet (LLJ) initially from the southern Plains

into the mid MO Valley Sunday morning is forecast to migrate east

into the mid MS and OH Valleys, immediately ahead of a surface low

tracking through the lower MO Valley into IL/IN. A cold front will

trail the surface low, likely extending southwest through the lower

MO Valley into southern KS or northern OK and the TX Panhandle by

mid to late afternoon.





...Missouri into the OH Valley...



Latest models remain consistent with previous runs in depicting one

or multiple MCSs ongoing at 12Z Sunday along the LLJ axis from

eastern KS into parts of northern and central MO. While the models

signal a general decrease in storm coverage through the morning, the

presence of modestly strong vertical shear suggests the potential

for isolated occurrences of damaging winds and perhaps some hail

across MO into western IL. 



Renewed storm development is anticipated by afternoon from IL/IN in

the vicinity of a remnant MCV west/southwest along the trailing

outflow/warm frontal boundary to the primary surface low over the

lower MO Valley. Enhanced warm thermal and moisture fluxes occurring

along the LLJ are expected to support air mass recovery in the wake

of the early-day storms with moderate to potentially strong

instability forecast from the lower OH Valley into the Ozarks, south

of the composite boundary. 



Forecast soundings and plan-view kinematic fields indicate

relatively strong low-level and deep-layer shear in the vicinity of

the composite boundary across portions of MO/IL/IN Sunday afternoon

into evening, where the highest probability of supercells and/or

bowing structures capable of all hazards (including strong

tornadoes) is expected to exist. However, as was alluded to in the

initial Day 2 discussion, and is still the case, there is

considerable latitudinal variability in the composite boundary

location. As such, uncertainty remains too high to delineate higher

severe-weather probabilities for this region.  





...Central High Plains...

  

A trailing vorticity lobe and western extension of a 40-50 kt

mid-level jet maximum are expected to support weak cyclogenesis

along a front or trough pushing into the region from the west. Ahead

of that boundary, steep low/mid-level lapse rates and modest

boundary-layer moisture content are expected to yield moderate

afternoon instability amidst sufficiently strong deep-layer shear to

support supercell storm modes capable of large to very large hail.

Most recent model guidance has shifted the corridor of preferred

storm development and residence slightly east across portions of

western and central NE into northwest KS, and the severe-weather

probabilities have been adjusted accordingly. Storms may congeal

into clusters Sunday evening with the severe-weather threat

transitioning more to damaging winds.





...Southern Kansas and northern Oklahoma into the Ozark Plateau...



High-resolution model guidance suggests that a sub-synoptic-scale

surface low/frontal wave may evolve Sunday afternoon along the

trailing front. Enhanced convergence near and east of that feature

should be sufficient to overcome the cap and allow for isolated to

widely scattered storm development. The combination of moderate to

strong instability and around 40 kt of deep-layer shear will support

supercells as the initial storm mode with a risk for large to very

large hail. A largely parallel orientation of the deep shear vector

to the surface front suggests the potential for merging storms

within a few hours after initiation, with damaging wind potential

increasing at that time. Storms are expected to grow upscale into

one or multiple MCSs with at least an isolated damaging-wind threat

spreading south through the Ozark Plateau region Sunday night.



..Mead.. 06/20/2026



$$