National Weather Service Raw Text Product

164 
ACUS01 KWNS 181957
SWODY1
SPC AC 181955

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0255 PM CDT Wed Jun 18 2025

Valid 182000Z - 191200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
MIDWEST AND LOWER GREAT LAKES...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MID
ATLANTIC REGION...

...SUMMARY...
Severe thunderstorms are expected this afternoon and evening from
parts of southeast Missouri northeastward to the southern Great
Lakes. Scattered to numerous damaging winds, isolated large hail,
and tornadoes all appear possible. Severe thunderstorms with
damaging winds may also develop across parts of the Mid-Atlantic.

...20z Update Midwest and Great Lakes...
A well-developed QLCS with multiple embedded bows and recent
measured severe gusts will continue eastward across IN and southern
lower MI this afternoon before reaching western OH this evening.
Moderate buoyancy and enhanced upper-level shear will support
continued storm organization with damaging gusts likely. Embedded
mesovorticies will also pose a risk for a few tornadoes. The main
changes to the outlook where to trim the Enhanced behind the
advancing QLCS.

Farther west near the core of the MCV, several clusters of miniature
supercells have a history of producing tornadoes. This may continue
for a couple more hours as storms near the MCV remain in 100-200
J/kg of low-level buoyancy and strong ambient vorticity. The
eastward extent of this threat is unclear as some overturning behind
the expanding QLCS will likely reduce the threat closer to the IN
border. Additional scattered storms across western MO behind the MCV
may also pose an isolated risk for damaging gusts and small hail
before weakening after dark.

...lower OH Valley...
Across far southeastern MO southern IL and western KY, additional
storm development will continue this afternoon and evening.
Displaced from the enhanced mid-level flow south of the MCV, a mixed
storm mode of supercells and line segments is expected. Large
buoyancy and the tendency for upscale growth suggests damaging winds
are likely. Low-level shear from the VWX/PAH VAD is maximized along
the low-level confluence axis which could also support a couple
tornadoes with the more discrete cells.

...Southern Plains...
A modified outflow boundary may serve as a focus for scattered storm
development from the TX Panhandle to southern OK this
afternoon/evening. 2000-3000 J/kg of MLCAPE and ~30 kt of deep-layer
flow will support organized clusters or transient supercells with a
risk for hail and damaging gusts. Have expanded the Slight Risk into
southwestern OK where storms appear  most likely to develop. See
MCD#1350 for additional short-term information.

..Lyons.. 06/18/2025

.PREV DISCUSSION... /ISSUED 1119 AM CDT Wed Jun 18 2025/

...Midwest...
A well-defined shortwave trough is currently over western MO,
tracking rapidly eastward.  At the surface, a low is centered over
northeast MO, with a very moist/unstable air mass in place across
much of IL/IN.  As large-scale forcing for ascent and strengthening
wind fields overspread the unstable warm sector, supercell
thunderstorms are expected to rapidly develop.  All severe hazards,
including a few tornadoes, appear possible through the afternoon as
storms track rapidly northeastward across IL into central/northern
IN.  Refer to MCD #1345 for further details.  Congealing outflow may
eventually lead to a greater damaging wind threat as storms spread
into lower MI and northern OH.

To the southeast of this early thunderstorm scenario, another zone
of convective initiation is expected from southeast MO into parts of
KY/southern IN.  These storms are more likely to grow upscale by
early evening, with a risk of damaging winds spreading into southern
OH and central KY.  Have expanded the ENH slightly eastward to
better cover this area.

...Mid Atlantic...
Visible satellite imagery shows mostly clear skies and strong
heating occurring over northern/central VA, where a hot/humid
airmass is present.  Thunderstorms are expected to develop off the
terrain this afternoon and spread eastward into the DelMarVa region.
 Sufficient flow aloft and steep low-level lapse rates will promote
a risk of strong storms capable wind damage.  Isolated strong storms
may also affect south-central VA and northern NC later this
afternoon as well. Refer to MCD #1344 for further details.

$$