Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1131 AM CDT Sun Jun 28 2026
Valid 281630Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN PLAINS...CAROLINAS...AND A PART OF THE MIDWEST...
...SUMMARY...
Severe thunderstorms are expected mainly tonight across the Dakotas.
Large to very large hail and severe winds are the primary hazards.
Thunderstorms capable of scattered wind damage are possible in parts
of the Carolinas.
...Dakotas/northern Plains...
A belt of south-southwesterly mid-level flow near 50 kt will be
maintained from Colorado to the Dakotas, east of the broad closed
low over the northern Great Basin/Rockies. A separate lee cyclone
is expected to form in the vicinity of northeast Colorado this
afternoon and then progress northeastward across Nebraska/South
Dakota overnight.
A few storms will be possible in North Dakota during the afternoon
with perhaps an isolated severe risk developing, but the primary
regional severe risk is expected tonight. Much of the severe threat
will likely focus after dark immediately north of the lee cyclone
into South Dakota as low-level moisture steadily spreads
west-northwestward. This increasing moisture and forcing for ascent
preceding the surface cyclone (and subtle embedded speed maxima
aloft) will likely support thunderstorm development overnight across
western South Dakota into southern North Dakota. The environment
will favor supercells, which will tend to be elevated, and small
thunderstorm clusters capable of large to very large hail and severe
wind gusts.
...Upper Mississippi Valley...
A bowing cluster has weakened and tended to grow downscale this
morning but otherwise persists across eastern Iowa at midday. Some
redevelopment/re-intensification could occur on the cluster's
southern periphery near a warm front. However, this is highly
uncertain given the increasing mid-level capping/EML advection the
remainder of the night.
Later tonight, a zone of low-level warm advection will be focused
across Wisconsin along the northeast edge of the warm elevated mixed
layer. Sufficient moistening above the surface and large CAPE will
favor the potential for at least isolated large hail/strong gusts
with mostly elevated storms tonight.
...Carolinas and far southern Virginia this afternoon/evening...
A convectively augmented mid-level disturbance over the southern
Appalachians will move southeastward into the Piedmont by this
afternoon. An airmass sampled by area 12 UTC raobs (PW near 2
inches) will heat/destabilize to the south of a patch of clouds that
are more prevalent over western North Carolina. Steepening low-level
lapse rates and a belt of slightly stronger westerly 3-6 km flow (30
kt) may act to loosely organize cold pools of developing
thunderstorm clusters. Isolated to scattered wind damage (50-60 mph
gusts) will be the primary hazard with the more intense water-loaded
thunderstorm cores until around sunset.
...West Texas late this afternoon/evening...
Strong surface heating and deep mixing along a sharpening dryline
will allow high-based thunderstorm development from late afternoon
through late evening. Flow aloft will be weak, but inverted-V
profiles will yield isolated severe outflow gusts of 60-75 mph.
..Guyer/Supinie.. 06/28/2026
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