ACUS01 KWNS 291232
SWODY1
SPC AC 291230

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0730 AM CDT Sun Jun 29 2025

Valid 291300Z - 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...
Belt of stronger westerlies will remain confined to the
U.S.-Canadian border states as a mid- to upper-level trough shifts
east from the MT/ND vicinity into the Upper Midwest late.  A surface
front is analyzed this morning from the Upper Midwest, where it is
ill defined and modulated by convective outflow, southwestward into
northern KS and arcing west-northwest into the central High Plains.
Some eastward movement is forecast during the day across the Upper
Midwest whereas the frontal segment over the central Great Plains
will become stationary this afternoon.  This boundary and associated
composite outflow will serve as the primary focus for renewed
shower/thunderstorm activity this afternoon into tonight.

A decaying MCS over western IA/southeast NE this morning will
further weaken and an ongoing corridor of weak thunderstorms extends
southeast from the MCS through the lower MO Valley.  Removed from
cloud debris, strong heating of a seasonably moist boundary layer
will result in strong destabilization from WI southwestward into KS,
where 2000-3500 J/kg MLCAPE is forecast by mid afternoon.  The
aforementioned displacement of this region from stronger mid and
high-level flow will limit potential for greater storm organization.
However, isolated to scattered thunderstorms will likely evolve into
several small-scale bands and clusters from the western Great Lakes
into the lower MO Valley posing mainly a wind risk with the stronger
storms.  Stronger heating farther west over central KS westward into
parts of the central High Plains will result in steep low to
mid-level tropospheric lapse rates.  Evaporative cooling of stronger
water-laden downdrafts will yield a threat for severe gusts across
the central Great Plains into the lower MO Valley.  Hail may
accompany the stronger cores, but this risk will be limited by a
deep melting layer and a multicellular storm mode.  A couple of
clusters may persist through the evening and into the overnight as
this activity shifts southward, perhaps into southeast KS and
northern OK late.

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.

...Mid Atlantic states...
A moist and moderately unstable airmass will favor isolated to
scattered thunderstorms developing during the afternoon across the
region.  High PW and steepened surface to 850-mb lapse rates amidst
weak shear will result in relatively disorganized individual storms
and smaller clusters.  Localized strong to severe gusts (50-60 mph)
may result and yield pockets of wind damage with the stronger cores.

..Smith/Broyles.. 06/29/2025

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