416
ACUS01 KWNS 251241
SWODY1
SPC AC 251239

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0739 AM CDT Wed Jun 25 2025

Valid 251300Z - 261200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CAROLINAS...SOUTHEAST...AND MID MISSOURI VALLEY...

...SUMMARY...
Severe wind gusts are possible from parts of the Carolinas into the
Southeast, with widely scattered strong to severe storms possible
from the northern High Plains eastward to the Mid Atlantic.

...Synopsis...
A large upper ridge remains in place over much of the eastern CONUS
this morning, although an upper low centered northeast of the
Bahamas is beginning to impinge on its southeastern periphery.
Early-morning satellite imagery also shows a well-defined shortwave
trough moving through southern CA and southern Great Basin.

Recent surface analysis reveals a large reservoir of low-level
moisture beneath this upper ridge, with low 70s dewpoints over much
of the OH and TN Valleys, Mid-Atlantic, and Southeast. This
low-level moisture extends across much of the Plains as well, with
mid 60s dewpoints reaching into south-central/southeast SD. A
diffuse, somewhat wavy stationary boundary exists between this moist
airmass and the drier, more continental airmass edging into the
northern Plains, Upper Midwest, and Great Lakes.

This large area of ample low-level moisture will support potential
thunderstorms much of the CONUS east of the Rockies. Highest
coverage of strong to severe storms is anticipated across the Mid MO
Valley and the Southeast/Mid-Atlantic, with more widely scattered
strong to severe storms across the northern and central High Plains
and along the frontal zone across the northern OH Valley.

...Mid-Atlantic/Southeast...
In addition to the moist airmass described in the synopsis, a pocket
of seasonally cold mid-level temperatures (i.e. around -10 deg C at
500 mb) associated with the Bahamas upper low extends into the
region. 12Z MHX and CHS soundings sampled -10 and -12 deg C at 500
mb, and 700-500 mb lapse rates of 7.9 and 8.4 deg C per km,
respectively. These thermodynamic conditions will result in very
strong buoyancy as the airmass diurnally heats this afternoon.
MLCAPE over 3000 J/kg is anticipated from AL eastward into the
Carolinas. Thunderstorm development is expected once convective
inhibition erodes around 18Z, with the very strong buoyancy
supporting intense updrafts. Vertical shear will be weak, with
erratic storm motions and a multicellular, pulse mode likely. Even
so, steep low-level lapse rates should support strong downdrafts and
numerous instances of damaging gusts are expected. These storms will
likely wane with the loss of daytime heating.

...Mid MO Valley into the Upper MS Valley...
Low-level moisture advection across the region today will bring low
70s dewpoints in southern MN by the late afternoon, while also
sharpening a warm frontal zone. By 18Z this warm front is forecast
to extend from a low over the central NE/SD border vicinity to near
the MN/IA border. Convergence along this boundary, as well as ascent
attendant to a convectively generated vorticity maximum rounding the
upper ridge, is expected to promote thunderstorm development within
the moderate buoyant airmass in place. Moderate southwesterly flow
aloft is anticipated over the region as well, with the resulting
combination of buoyancy and shear supporting strong to severe
storms. A few supercells are possible, but one or more bowing line
segments capable of damaging gusts are the primary severe threat.

...Northern/Central High Plains...
The shortwave trough that currently extends from central MT trough
eastern ID is forecast to continue eastward today. Ahead of the
trough, a moist and unstable airmass will be in place by afternoon
from eastern Colorado northwestward into eastern Montana. As surface
temperatures warm today, scattered convective initiation will take
place in the higher terrain, with storms moving east-northeastward
into the lower elevations during the afternoon. Vertical shear will
be modest, with the strongest shear across the northern High Plains,
but high cloud bases and steep low-level lapse rates could still
support damaging wind gusts along surging cold pools. Isolated hail
is possible across the higher terrain as well.

..Mosier/Wendt.. 06/25/2025

$$