353
ACUS01 KWNS 290551
SWODY1
SPC AC 290550

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1250 AM CDT Sun Jun 29 2025

Valid 291200Z - 301200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
MIDWEST TO THE CENTRAL HIGH PLAINS...

...SUMMARY...
Isolated to scattered strong to severe thunderstorms are possible
from the upper Great Lakes into the central High Plains. Wind is the
primary risk, though hail is expected across portions of the High
Plains.

...Upper Great Lakes to the Central High Plains...

Broadly cyclonic westerlies, currently noted over the northern
Plains, will gradually shift east and sag south across the upper MS
Valley late in the period. Mid-level flow south of I-70 will remain
seasonally weak, and the prospect for organized convection south of
this corridor is low.

Early this morning, a weak synoptic front stretched from
northwestern MN into northern NE before arcing into eastern WY. This
boundary is forecast to sag south and east through the period with a
late-afternoon position expected from northern WI-central
IA-northwest KS-arcing into southeast WY. This boundary will likely
serve as the focus for robust convection during the
afternoon/evening hours. Diurnal heating will prove instrumental in
convective development and the strongest boundary-layer heating will
be noted across the High Plains into extreme southeast NE.
Convective temperatures will be easily breached along the boundary
over northern KS as temperatures soar through the upper 90s to near
100F. Forecast soundings exhibit cloud bases near 3km in this
environment and fairly high PWs favor damaging winds despite the
relative weak shear across this region.

Farther northeast, remnants of early-day convection will spread
across southern MN/northwest IA. This activity will propagate
southeast and likely influence redevelopment where differential
heating is greatest. Some short-range guidance suggests an MCS may
propagate south along the NE/IA border, with some upscale growth
possible by early evening. While not all models agree, this signal
is likely real, especially as a weak LLJ is forecast across eastern
KS into northwest MO into the evening.

Another corridor where strong/severe convection is expected is
across the High Plains from eastern WY into northeast CO. Northwest
flow is forecast to strengthen across the northern High Plains along
the back side of the trough. Isolated supercells are expected to
develop along the synoptic front that will be draped across this
region. Forecast soundings do not exhibit strong buoyancy, but
modest shear and moist profiles favor organized updrafts that should
spread southeast toward the NE Panhandle. Large hail and wind are
expected.

...Middle Atlantic...

Seasonally high PW values and light west-southwesterly mid-level
flow will once again favor a few slow-moving line segments and
clusters. Storms will be diurnally driven, and convection should
focus along a very weak zone of low-level confluence that should
extend across the Delmarva into central VA. Locally strong gusts are
the primary concern.

..Darrow/Lyons.. 06/29/2025

$$