LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0753 AM CDT Thu Jun 29 2023
Valid 291300Z - 301200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THROUGH THIS
EVENING FROM NORTHERN MO TO IL...SOUTHWEST IN AND WESTERN KY...
...SUMMARY...
Swaths of damaging winds of 60-80 mph, large hail up to 2.5 inches
in diameter, and a couple of tornadoes will all be possible today
from northern Missouri into Illinois and adjacent areas of southwest
Indiana and western Kentucky. Other severe storms with large hail
and damaging gusts will also be possible farther west into the
central High Plains.
...MO/IL/IN/KY/TN through this evening...
Severe storm clusters, with embedded supercells, have been moving
eastward early this morning near KS/NE border and are expected to
continue eastward through late morning across northern MO and
extreme southern IA, near a stalled front. A moist/unstable air
mass is present along and south of the front, with MLCAPE of
3000-4000 J/kg across northern MO, driven by boundary-layer
dewpoints in the low-mid 70s beneath midlevel lapse rates of 9 C/km.
These favorable thermodynamic profiles will favor continued strong
updraft formation within the clusters as they move along the front
and the north edge of the warmest elevated mixed layer, coincident
with the southern fringe of the stronger midlevel westerlies.
Isolated very large hail to 2.5 inches in diameter will be possible
through the morning with the supercells, while large DCAPE favors a
continuation of severe outflow gusts (60-80 mph). Though the
details are still a bit uncertain, there is the potential for some
upscale growth into a bowing MCS with swaths of significant wind
damage from northern MO into IL and southwest IN.
Once the expected MCS reaches central IL, the tendency should be for
more southeastward motion with time, around the periphery of the
midlevel ridge. The ongoing storms from eastern IL into southwest
IN have shown some tendency to cluster this morning, and may persist
for a few more hours while moving southeastward toward KY.
Rain-cooled air from these morning storms could also provide a
corridor for the upstream convection to move along this afternoon.
The main threat with the morning storms will be large hail,
primarily with elevated supercells, though some wind damage will
also be possible. Damaging winds will be the main threat with the
expected MCS this afternoon, and a couple of tornadoes may also
occur with embedded circulations.
...Central High Plains this afternoon/evening...
Post-frontal, upslope flow is established across eastern CO, and
low-level moisture has spread west to the Front Range (aided by
outflow from overnight storms). Modification of the rain-cooled air
and breaks in the low clouds will support moderate buoyancy by mid
afternoon (MLCAPE of 1000-2000 J/kg), when thunderstorm development
will become more probable immediately east of the higher terrain
from CO into southeast WY. The moderate buoyancy and relatively long
hodographs with effective bulk shear in excess of 40 kt will support
supercells capable of producing large hail of 1-2 inches in
diameter. Some upscale growth into a few clusters will be possible
this evening, with an attendant threat for isolated damaging winds.
Though the details are fairly uncertain, some of the evening
convection may persist into the overnight hours across southern
NE/northern KS with some threat for isolated large hail/wind damage.
..Thompson/Gleason.. 06/29/2023
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