RSS Mesoscale Discussions from Storm Prediction Center
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1132 AM CDT Wed Jun 10 2026
Valid 101300Z - 111200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE UPPER/MID MISSISSIPPI VALLEYS AND MIDWEST...
...SUMMARY...
Scattered to numerous severe thunderstorms with potential for large
hail in excess of two inches in diameter, a few strong tornadoes and
damaging winds with gusts over 75 mph are expected this afternoon
and evening across parts of the Upper Mississippi Valley and
Midwest.
...Mid/Upper MS Valley into the central Plains...
Regional radar imagery shows an ongoing cluster of strong
thunderstorms across southern IA and northern MO, supported by a
residual low-level jet that currently extends from KS/northern OK
into the region. Heating of the very moist airmass downstream will
result in limited convective inhibition and strong to very strong
buoyancy by the early afternoon. Reintensification of the ongoing
cluster is anticipated as it moves within this destabilizing
airmass. Deep-layer shear will be modest but still sufficient for
some organization, and the development of a strong to occasionally
severe bowing line segment appears probable, particularly from
northeast IA into southern WI and northern IL. New updrafts ahead of
the line could also produce hail early in the convective cycle,
while also potentially contributing to updraft augmentation as they
merge into the line. Some isolated hail could result from this
augmentation as well.
Farther north, recent surface analysis placed a triple point low
over northeast SD. An occluded front extends north-northwestward
from this low across eastern ND into central Manitoba, while cold
front extends southward to another low over northeast NE and then
back southwestward across the central Plains. The frontal zone and
triple point low are forecast to progress eastward into the Upper
Midwest, interacting with a diurnally destabilizing airmass to
support thunderstorm development. Ample low-level moisture (i.e.
dewpoints in the upper 60s/low 70s) will support strong buoyancy,
despite modest lapse rates, and moderate deep-layer vertical shear
should be sufficient for updraft organization. As a result, strong
to severe thunderstorms are expected along and just ahead the front,
with large hail as the primary threat. Isolated very large hail to
2" in diameter could occur. Some damaging gusts are possible as
storms transition into bowing line segments over time. There is also
a low-probability for a few brief tornadoes, particularly with any
more cellular development from central into eastern WI from 21 to
00Z.
An additional severe threat will likely materialize this evening in
the wake of the afternoon MCS within the recovered airmass from the
Mid MS Valley westward through the Mid MO Valley into the central
Plains. The impetus for this redevelopment will likely be a complex
combination of low-level convergence along the approaching front,
low-level convergence and warm-air advection along remnant outflow,
and modest large-scale ascent. Development along the front appears
most likely from central IA southwestward into northeast KS, while
development along the outflow appears most likely northwest IL
across southern IA. The airmass in all of these areas will likely
feature ample low-level moisture (i.e. dewpoints in the low to mid
70s), warm surface temperatures (highs in the low 90s), and at least
modestly steep mid-level lapse rates. This will result in strong to
extreme buoyancy, with MLCAPE values exceeding 3000 J/kg from
northeast KS into southern IA, northern MO, and west-central IL.
Complex surface pattern will likely yield limited predictability for
the primary severe hazard this evening. Given the extreme buoyancy
and moderate mid-level flow, any more cellular development that is
able to mature should become supercellular, with all severe hazards
possible, including very large hail and tornadoes. Storm interaction
and strong downdrafts will likely make maintaining a discrete mode
difficult, but low-level hodographs support the potential for a
strong tornado, particularly from 00 to 03Z amid a strengthening
low-level jet.
Lastly, early morning strong to severe thunderstorms are possible
across central/eastern NE as a secondary branch of the low-level jet
develops in response to another shortwave trough moving into the
central High Plains.
...Ohio Valley/Central Appalachians/Mid-Atlantic States...
A moist and unstable airmass will be in place today across much of
the region, with surface dewpoints generally in the lower 70s F.
While some thunderstorms are ongoing early today, additional and
more potent thunderstorm development is expected into the afternoon
as the boundary layer destabilizes. These storms will be further
influenced by a pair of weak eastward-moving MCVs, one over the
upper Ohio River Valley and the other over the central Appalachians.
Damaging winds, associated with water-loaded downbursts, will be the
primary hazard regionally.
..Mosier/Flournoy.. 06/10/2026
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