Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1233 AM CDT Sat Jun 27 2026
Valid 271200Z - 281200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS LATE THIS
AFTERNOON INTO EARLY TONIGHT ACROSS EASTERN MT AND WESTERN ND...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS INTO WESTERN SOUTH
DAKOTA AND NEBRASKA...AND ACROSS NORTH CAROLINA...
...SUMMARY...
A mix of initial supercells and later storm clusters will produce
swaths of severe outflow winds and very large hail across the
northern High Plains late this afternoon into early tonight.
Isolated wind damage will also be possible from the Mid-Mississippi
Valley to the Carolinas, as well as across west Texas and the Texas
Panhandle.
...Northern High Plains this afternoon into tonight...
Embedded speed maxima will rotate northeastward over the northern
High Plains, around the eastern periphery of a close midlevel low
evolving over the northern Great Basin and northern Rockies.
Boundary-layer dewpoints in the 60s will continue to spread
northward from KS/NE to the Dakotas, east of a deep lee
trough/cyclone across the central/northern High Plains. The
moistening will occur beneath steep midlevel lapse rates, which
combined with daytime heating will result in large CAPE.
Thunderstorm development is expected this afternoon along both the
surface trough/lee cyclone near the MT/ND border and near the Big
Horn Mountains. The initial storms could be supercells with very
large hail (2-3 inch diameter) near the ND/MT border, and a couple
of tornadoes with any supercells anchored along the surface
boundary, though relatively large temperature-dewpoint spreads and
mode concerns could temper the tornado threat somewhat. By late
evening and early tonight, storms will likely grow upscale and move
northeastward across ND as one or more MCSs with severe outflow
winds (potentially 80+ mph) in the steep lapse rate environment.
More isolated supercells will also be possible farther south into
western SD/NE where isolated very large hail and significant severe
outflow gusts will be possible.
...TN/southern KY to NC this afternoon...
An MCV now over eastern KY will continue eastward near the VA/NC
border during the day, and additional MCVs are likely to emerge from
ongoing storm clusters moving eastward across OK, southwest KS and
the TX Panhandle. Ascent with the MCVs, as well as residual
outflow/differential heating zones, will help focus thunderstorm
development during the afternoon in a moist, unstable environment.
Occasional wind damage will be possible with storm clusters where
low-level lapse rates are relatively steep (south of persistent
clouds) and there is some enhancement of midlevel flow. An isolated
tornado may also occur in the warm advection zone with enhanced
low-level hodograph curvature across TN on the southwest flank of
the western MCV, though confidence in this scenario is low.
...TX Panhandle into west TX late this afternoon/evening...
Though forcing for ascent will be weak at best this far south,
strong surface heating/mixing along the lee trough/dryline could
support high-based thunderstorm development late this afternoon.
Inverted-V profiles will favor the potential for isolated severe
outflow gusts of 60-75 mph.
..Thompson/Chalmers.. 06/27/2026
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