Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1245 AM CDT Fri Jun 26 2026
Valid 261200Z - 271200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING ACROSS PARTS OF THE OZARKS PLATEAU INTO LOWER OHIO VALLEY
AND ACROSS PARTS OF THE NORTHERN ROCKIES INTO ADJACENT GREAT
PLAINS...
...SUMMARY...
Scattered severe thunderstorm development is possible today,
particularly this afternoon into tonight across parts of the Ozark
Plateau into lower Ohio Valley and across parts of the northern
Rockies into adjacent Great Plains.
...Discussion...
Models indicate that amplification of mid/upper flow across the
eastern mid-latitude Pacific into western North America will
continue through this period, with large-scale troughing and an
embedded cyclonic circulation digging inland across the Pacific
Northwest through Great Basin and northern Rockies, downstream of
building ridging. As this occurs, ridging is likely to build across
the northern Great Plains through upper Mississippi Valley, but
broadly confluent, zonal flow is forecast to persist east of the
mid/upper Mississippi Valley, in the wake of a mid-level trough
accelerating east of the lower Great Lakes through New England and
the Canadian Maritimes. On the southern periphery of this regime, a
number of convectively generated perturbations may progress across
the Ozarks Plateau and lower Ohio Valley through Mid Atlantic today
through tonight.
In lower levels, a weak surface low is forecast to migrate
east-northeast of the lower Great Lakes into northern New England,
before weakening. This may be accompanied by a reinforcing influx
of somewhat cooler and drier area, in the wake of an
ill-defined/diffuse preceding front overspreading the northern Mid
Atlantic. To the west of the Appalachians, this boundary may become
augmented in locations by convective outflow and developing areas of
strengthening differential surface heating during the day. Across
the high plains, fairly significant surface cyclogenesis centered
across southeastern Montana is probable by 12Z Saturday, with
deepening surface troughing southward to the lee of the Rockies.
As a notable plume of very warm elevated mixed-layer air spreads
east of the higher terrain, through much of the Great Plains,
initiation of stronger thunderstorm development may largely be
confined to the higher terrain, before propagating into the
deepening surface troughing across the adjacent plains. Otherwise,
to the east of the Great Plains, forcing for ascent and
destabilization along the weak front, and within low-level warm
advection to the east-southeast of the weak low, may provide support
for at least widely scattered strong to severe storm development.
...Ozark Plateau into lower Ohio Valley...
Higher coverage of potential strong to severe thunderstorm
development may generally focus across this region, aided by at
least a couple of convectively generated perturbations. There is
spread among the various model output, but it still appears that
this could include a fairly notable MCV migrating into the lower
Ohio Valley by around 19-21Z, along a better-defined segment of the
low-level baroclinic zone. With surface dew points forecast near
70F, and a convectively augmented belt of flow on the order of 30-50
kt in the 850-500 mb layer contributing to sufficient shear for
supercell structures, a couple of tornadoes appear possible in a
corridor roughly centered along the Ohio River. Otherwise, several
clusters of thunderstorms may evolve this afternoon and evening,
possibly accompanied by developing corridors of strong to severe
wind gusts.
...Northern Rockies into adjacent Great Plains...
Given a corridor of at least weak to moderate boundary-layer
destabilization near and to the lee of the higher terrain, forcing
for ascent and strengthening vertical shear downstream of the
digging large-scale troughing probably will become supportive of a
period of organized severe thunderstorm development late this
afternoon through evening. This may include supercells and
organizing clusters posing a risk for severe hail and wind, and at
least some potential for a tornado or two.
..Kerr/Chalmers.. 06/26/2026
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