376
ACUS02 KWNS 251734
SWODY2
SPC AC 251733

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1233 PM CDT Sat May 25 2024

Valid 261200Z - 271200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERN
MISSOURI TO CENTRAL/SOUTHERN ILLINOIS AND INDIANA...MUCH OF
KENTUCKY...AND NORTHERN TENNESSEE...

...SUMMARY...
Widespread strong to severe thunderstorm development appears likely
across parts of the southeastern Great Plains and lower Missouri
Valley into the Ohio and Tennessee Valleys Sunday afternoon through
Sunday night. Multiple rounds of storms with the threat for large
hail, damaging wind gusts, and a few tornadoes appears likely across
parts of east central Missouri and west central Illinois through
much of Kentucky and adjacent portions of northern Tennessee.

...Synopsis...
A progressive mid-level trough will traverse the central CONUS and
into the Midwest and Great Lakes on Sunday and Sunday night. The
associated surface low will begin the period in central Kansas and
somewhere near Lake Michigan/Lower Michigan by 12Z Monday. Along and
south of this surface low, a moist/unstable warm sector will support
multiple rounds of strong to severe storms.

...Missouri through central/southern Illinois/Indiana, Kentucky, and
northern Tennessee...
A convectively enhanced mid-level shortwave trough, responsible for
the D1 severe weather episode in the central Plains is progged to be
near the IA/IL/MO border at 12Z with a broad area of likely severe
thunderstorms extending to the south. Storms on the northern end of
this line will likely outrun the best instability and weaken during
the morning, especially by the time they reach Lake Michigan.
Farther south, low-level moisture advection will lead to rapid
destabilization ahead of the line. This will support a sustained to
perhaps increased severe weather threat as this line moves across
southern Illinois and Indiana and into northern Kentucky. The
primary threat with this activity will be damaging wind gusts.

Despite the stabilizing effect of this morning convection, recovery
is anticipated across southern/eastern Missouri during the afternoon
and eventually into southern Illinois and western Kentucky as a
stout EML advects across the region from the west. The exact
evolution of storm development in the wake of morning convection
remains unclear. Persistent supercell development is possible on the
remnant outflow boundary through the day which would have a
continued wind/hail threat and could grow upscale into a cluster
with an increased wind threat. However, even if storms do not
continue to form along this boundary, additional storms are likely
during the late afternoon/evening as a secondary shortwave trough
approaches and erodes inhibition. 45 to 50 knots of effective shear
will support supercell storm mode with a primary threat of large
hail. In addition, if sufficient boundary layer recovery can occur
north of the outflow boundary, the environment would be quite
favorable for tornadoes with large low-level hodographs. A 10%
hatched tornado threat has been added for the region where this
threat may be greatest.

Eventually, more widespread thunderstorm development is expected
along the advancing cold front during the late evening which should
move southeast and persist for the entire overnight period. This
will pose a primary threat for damaging winds although there will be
some tornado threat given the strengthening low-level jet during the
evening hours. The orientation of the line will be the primary
limiting factor to a greater tornado threat with this overnight
squall line.

...Eastern Oklahoma and northeast Texas into Arkansas...
A strongly unstable and only slightly capped environment is expected
during the afternoon hours. Isolated supercells capable of large
hail are possible during the afternoon as ascent from the mid-level
trough overspread this region, but low-level focus will be nebulous.
The better storm threat will arrive with the cold front during the
evening with a damaging wind threat. However, some large hail is
also possible with more scattered development/potentially transient
supercell development on the southern extent of the line.

...Northern Illinois and southeast Wisconsin...
A narrow area near the surface low may destabilize during the late
afternoon/early evening with sufficient instability for a low-topped
hail/wind threat near the surface low for a few hours during the
early evening hours.

...Eastern Kansas...
Remnant low-level moisture behind the cold front, combined with cold
air advection aloft will lead to some destabilization behind the
cold front during the afternoon/evening. A few southeastward moving
storms/clusters may pose a large hail/damaging wind threat with the
threat waning after sunset.

...Eastern Arkansas across northern MS/AL and southern Tennessee...
A squall line along/ahead of the approaching cold front will move
across the Mid-MS Valley into southern TN/northern AL after
midnight. A very moist/unstable boundary layer and strong deep layer
shear will support a damaging wind threat through the overnight
hours. Some guidance indicates storm development ahead of the line
across AL/TN/MS which would have a threat for all severe hazards
given the steep mid-level lapse rates and strong low-level and
deep-layer shear.

..Bentley.. 05/25/2024

$$