spc ac 210559
day 2 convective outlook
nws storm prediction center norman ok
1259 am cdt sun jun 21 2026
valid 221200z - 231200z
...there is a slight risk of severe thunderstorms for portions of
the carolinas into the mid-atlantic and for the central/northern
high plains....
...summary...
scattered severe storms appear possible across portions of the
mid-atlantic monday afternoon and evening. more isolated severe
weather is expected along a frontal zone that will extend from the
southern appalachians to the mid-south and southern plains.
additionally, a widely scattered severe weather threat is expected
across the central and northern high plains monday afternoon and
evening.
...synopsis...
mostly zonal flow is expected across the conus on monday with
multiple embedded shortwave troughs within the flow pattern from the
central plains to the mid-atlantic. a weak surface low is expected
to movefrom the appalachians to the mid-atlantic, associated with
the strongest of the mid-level jet streaks within the broader flow.
an additional lee cyclone is expected to develop along the southern
high plains during the period with a surface front connecting these
two features.
...mid-atlantic...
moderate instability is forecast to develop east of the appalachians
from the carolinas into the mid-atlantic on monday beneath up to 50
knots of mid-level flow. this combination of shear and instability
will support storm organization, including the potential for some
supercells. neutral to potentially weak height rises may limit storm
coverage across the region, which may preclude a more widespread
severe wind threat. however, given the steep low-level lapse rates
where temperatures are forecast to warm into the mid 90s, damaging
winds will be likely from any storms that develop.
a narrow zone near the warm front will have a greater tornado threat
given the enhanced shear from a compact, but strong, low-level jet
across northern virginia into the delmarva. a 5% tornado contour may
eventually be needed within this zone, but given the relatively
narrow zone of threat and some uncertainty where this front will be
by monday afternoon/evening, higher probabilities will not be added
at this time.
...central/northern high plains...
weak lee cyclogenesis is forecast across eastern wyoming during the
day monday. this will strengthen upslope flow across the
central/northern plains. moderate instability and strengthening
west-northwesterly flow aloft of 40 to 45 knots will result in an
environment that supports widely scattered supercells with the
potential for large to very large hail and perhaps some isolated
wind gusts.
...northwest texas and vicinity...
a more conditional severe weather threat will exist across northwest
texas and vicinity where there is potential for an outflow boundary
from the morning mcs across oklahoma to intersect the dryline.
height rises aloft and strong inhibition should mostly suppress
convection. however, mesoscale convergence at the intersection of
these boundaries could result in one or two supercells capable of
all severe hazards. however, given the conditionality of this
mesoscale threat, higher probabilities have not been added at this
time.
...mid-mississippi valley...
moderate to strong destabilization is forecast ahead of and south of
a morning mcs that should be in the oklahoma/arkansas region on
monday morning. reinvigoration of the ongoing mcs or additional
development may result in some isolated damaging wind threat.
however, overall very weak mid-level lapse rates and weaker shear
where the greatest instability is forecast, should keep the threat
mostly marginal/isolated.
..bentley.. 06/21/2026
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note: the next day 2 outlook is scheduled by 1730z