Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0734 AM CDT Tue Jun 30 2026
Valid 301300Z - 011200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR WESTERN
KANSAS...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
ENHANCED RISK AND OVER THE UPPER GREAT LAKES AND PARTS OF THE
NORTHEAST...
...SUMMARY...
Scattered severe thunderstorms are probable over parts of the
central High Plains, with severe wind gusts (60 to 85 mph) being the
primary hazard during the late afternoon and evening.
...Synopsis...
Water-vapor imagery this morning shows a mid- to upper-level low
near the ND/Canadian border and a weak disturbance cresting a
mid-level ridge over southeastern ON and moving towards NY.
Downstream of a mid-level trough over the Southwest, a couple of
weak mid-level vorticity maxima over the southern and central High
Plains will slowly migrate northeast around the periphery of a
mid-level anticyclone centered over TN. A front will push east
across parts of the Upper Midwest and extend southwestward into the
central High Plains near a weak low. A weak lee trough/dryline will
focus storm development from western KS southward into the southern
High Plains.
...Southern/Central High Plains...
Perhaps associated with a weak disturbance, scattered thunderstorms
are forecast later this afternoon over the High Plains on the
western rim of richer low-level moisture and strong insolation.
Model guidance shows considerable erosion of the capping layer by
mid afternoon with MLCAPE ranging from 1500 J/kg over the TX South
Plains to 3500 J/kg over western KS. Initially higher-based
convection will gradually move east into richer moisture and promote
larger thunderstorm cores and increased potential for storm clusters
to develop. Large hail will be possible with any supercell activity
(i.e., most probable from the northern TX Panhandle into KS; 25-40
kt effective shear). However, very steep surface to 300-mb lapse
rates will favor strong evaporative cooling with the more intense
cores. Ample deep-layer shear for organized storms but
veering/backing of flow with height will aid in storm outflow
aggregating as linear clusters become the primary storm mode with
time. These organized but linear clusters will likely be efficient
in promoting severe wind gusts (60-85 mph) during the early evening,
coincident with a strengthening LLJ and WAA before this threat wanes
by late evening. Weaker deep-layer shear farther south in the
southern High Plains will likely limit both storm organization and
overall coverage of the wind risk.
...Upper Midwest/Great Lakes...
An ongoing area of showers and isolated thunderstorms over the upper
MS Valley will likely translate east-northeast today in conjunction
with a convectively augmented mid-level disturbance over southern MN
this morning. Ahead of this activity, a fetch of very rich moisture
will be maintained within south-southwesterly low-level flow. As
the boundary layer destabilizes ahead of this disturbance,
additional storms are forecast to develop later today within a very
to extremely unstable airmass. Ample tropospheric flow will support
organized storms, including supercells capable primarily of a
hail/wind risk and perhaps a tornado. By late evening,
strengthening WAA across NE and the mid MO Valley implies widely
scattered storms developing during the mid-late evening, with this
activity shifting northeast during the overnight. Isolated
hail/wind are the main threats with the stronger storms.
...Northeast...
A belt of 30-40 kt 500-mb northwesterly flow will reside across the
Northeast today. There is uncertainty regarding boundary layer
destabilization over portions of this region. Nonetheless, weak to
moderate destabilization is progged by model guidance with isolated
to scattered storms developing by early afternoon. A couple of
short-lived supercells are possible before one or more
clusters/bowing segments develop and spread south and eastward with
damaging wind potential.
...Southeastern US...
Located to the south of an upper high centered over the OH/TN
Valley, a very moist air mass will be present across much of the
region. Strong heating will yield moderate buoyancy by early
afternoon. Forecast soundings depict around 20-kt effective shear
which will aid in minor multicellular organization. Localized 50-60
mph gusts capable of isolated wind damage will probably accompany
the stronger storms.
..Smith/Dean.. 06/30/2026
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