Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1233 AM CDT Tue Jun 24 2025
Valid 241200Z - 251200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL AND NORTHERN HIGH PLAINS...
...SUMMARY...
Storms associated with very large hail and severe wind gusts will be
likely this afternoon and evening in parts of the central and
northern High Plains. Marginally severe storms will be possible this
afternoon from part of the central and northern Plains eastward into
the Northeast.
...Central and Northern High Plains...
A mid-level anticyclone will remain in place today across much of
the southeastern third of the nation, as west-northwesterly
mid-level flow continues from the north-central U.S. into the Great
Lakes. At the surface, a post-frontal airmass will be located over
the central and northern High Plains, where surface dewpoints will
be mostly from the mid 50s to the mid 60s F. As surface temperatures
warm during the day, moderate instability will develop across parts
of the region, and scattered convection will initiate in the higher
terrain. These storms will move eastward into the lower elevations
of the High Plains this afternoon.
RAP forecast soundings from eastern Wyoming into northeastern
Colorado at 21Z have 40 to 50 knots of deep-layer shear, with
700-500 mb lapse rates around 8 C/Km. This environment will support
the development of supercells with large hail. Hailstones of greater
than 2 inches in diameter will be possible with supercells that
become particularly intense. In areas where convective coverage is
greatest, the cells could congeal into short line segments capable
of severe gusts. The severe threat should be greatest from late
afternoon to mid evening.
....Central and Northern Plains/Mid to Upper Mississippi
Valley/Lower Great Lakes/Northeast...
The northern edge of a mid-level anticyclone will remain from the
mid Mississippi Valley east-northeastward into the central
Appalachians today. To the north of the anticyclone,
west-southwesterly mid-level flow will be in place. At the surface,
a front will be positioned from the central Plains
east-northeastward into the lower Great Lakes and Northeast. Near
and to the south of the front, surface dewpoints from the mid 60s to
the lower 70s F will contribute to the development of moderate
instability by afternoon. This, along with increasing low-level
convergence near the front, will result in scattered convective
initiation. Several clusters or line segments are expected to
develop and move eastward into the stronger instability. Although
deep-layer shear will remain on the marginal side for organized
storms, low-level lapse rates will become steep in the mid to late
afternoon. This could support a marginal wind-damage threat with the
stronger multicell line segments in areas that heat up the most.
..Broyles/Moore.. 06/24/2025
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