574
ACUS01 KWNS 250602
SWODY1
SPC AC 250601

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0101 AM CDT Tue Jun 25 2024

Valid 251200Z - 261200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE CENTRAL PLAINS...MIDWEST AND MID MISSISSIPPI VALLEY...

...SUMMARY...
Scattered severe thunderstorms are possible across parts of the
central/southern Great Plains and Midwest late this afternoon and
evening. Damaging wind gusts, large hail, and a tornado or two may
are possible.

...Central Plains and Midwest...
A complex and highly uncertain forecast scenario is likely to evolve
today, as the remnants of one or more convective clusters interacts
with a broadly moist and unstable air mass over the Midwest and
central Plains. Early in the period, an MCS may be ongoing across
parts of the southern Great Lakes and OH Valley. Near the eastern
extent of the buoyancy plume reintensification of the eastern most
convection/remnants thereof appears unlikely through the morning
across the mid to upper OH Valley.

Farther west across IL and IN, any ongoing storms or remnant
outflow, should continue south and may reintensify/reinvigorate over
the mid MS Valley by mid morning. While mid-level flow decreases
with southern extent, moderate buoyancy may sustain a risk for
damaging gusts with a loosely organized cluster/MCS, potentially as
far south as the lower OH/Mid MS Valley this evening.

A greater focus for severe convection appears likely to evolve along
the slow-moving synoptic cold front drifting south across the
central Plains. Strong heating along the front ahead of a subtle
shortwave trough will allow for isolated storm development this
afternoon. Model soundings show enhanced mid and upper-level shear
profiles, along with steep mid-level lapse rates. Supercells may
evolve with an initial risk for large hail, given MLCAPE of
4000-5000 J/kg and the discrete mode. A brief tornado or two may
also be possible with enhanced vertical voritcity and low-level
shear near the front.

With time, mostly front-parallel flow will favor upscale growth into
clusters and potentially an MCS over eastern NE and IA. With
plentiful MLCAPE (2000-3000 J/Kg) in place over the region, damaging
winds will remain possible as storms track east/southeast into the
eastern central Plains and the mid MS Valley. The exact
eastern/southern extent of any severe risk remains quite uncertain,
given the tendency for storms to outrun the stronger upper-level
support. Still, a few CAM members suggest a coherent line of storms
will continue overnight reaching southern MO/IL and eastern KS
before the start of the Day2 period.

...KS OK and the TX Panhandle...
On the northern fringes of the subtropical ridge over the southern
third of the CONUS, robust diurnal heating should support very hot
daytime temperatures along and east of dryline from west-central KS,
into northwest OK and the TX Panhandle. As the western portion of
the ridge intensifies, flow aloft should gradually veer to
northwesterly as a weak mid-level perturbation traverses the
periphery of the ridge and moves out of the central Rockies. Weak
ascent should overlap with near-convective surface temps in the low
100s F during the later afternoon, supporting isolated to widely
scattered thunderstorm development along and east of the dryline.
Moderate buoyancy within the well-mixed but moist surface air mass,
along with enhanced mid and upper-level flow, will favor a mixed
mode of high-based multicell clusters and perhaps transient
supercells capable of damaging gusts and isolated hail. The
longevity of these storms is somewhat questionable, given the
tendency for weakening upper-level support and warming mid-level
temperature to the south, but at least an isolated severe risk may
persist into parts of central OK/KS into the early evening.

...Dakotas and western MN...
Behind the main synoptic front, daytime heating over residual
boundary-layer moisture should support the development of moderate
buoyancy ahead of a second weaker cold front moving out of southern
Canada. A shortwave trough over the northern Rockies is forecast to
intensify as it moves southeast into the Plains. Modest forcing for
ascent coupled with weak low-level warm advection may support
isolated storm development late in the afternoon, eventually moving
into the eastern Dakotas and western MN by early evening. Relatively
long and straight hodographs suggest the potential for a few
elevated supercells with a risk for isolated large hail.

..Lyons/Barnes.. 06/25/2024

$$