spc ac 181729
day 2 convective outlook
nws storm prediction center norman ok
1129 am cst wed feb 18 2026
valid 191200z - 201200z
...there is a slight risk of severe thunderstorms across portions of
the middle mississippi valley and lower ohio valley...
...summary...
severe thunderstorms, with potential to produce a few tornadoes,
hail and damaging wind gusts, are possible across parts of the
middle mississippi into lower ohio valleys thursday afternoon into
early evening.
...synopsis...
a progressive mid-level flow regime, characterized by multiple
low-amplitudes perturbations and strong west/southwesterly flow
aloft is expected over the conus day2/thursday. the primary
shortwave trough will move from the southern rockies/plains into the
midwest by 00z, assuming a slight negative tilt as multiple weaker
preceding subtropical perturbation are absorbed. strong ascent
associated with the trough a 100+ kt mid-level jet streak will
deepen a surface low over the eastern plains, reaching the great
lakes by early friday.
...middle mississippi and lower ohio valley...
as the upper trough and surface low approach the mid ms valley early
thursday, rapid low-level moistening is expected across parts of
eastern mo western il and the lower oh valley. while moisture
content is seasonably limited (surface dewpoints in the 50s to near
60 f), cooling mid-level temperatures ahead of the preceding
subtropical shortwave trough will support some destabilization
thursday afternoon.
while instability will remain modest owing to limited boundary-layer
moisture, clearing ahead of a surging dryline tied to the surface
low will allow for diurnal heating. in combination with steepening
mid-level lapse rates, around 500-1000 j/kg of mlcape is exacted by
early afternoon. an arc of mainly cellular convection should develop
by mid afternoon across far eastern mo and western to south-central
il and move quickly eastward. amid very strong kinematic fields
(ebwd 55+ kt) a supercell mode is expected. strong low-level shear
and the concentration of buoyancy in the lowest few km will favor
strong vertical accelerations and stretching with seasonably cool
mid-level temperatures. hail is likely with the stronger rotating
storms. additionally, with backed low-level flow near the low/warm
front and large low-level shear, (0-1 km bwd 25+ kt) a few tornadoes
are possible.
as ascent spreads eastward, thunderstorm activity may eventually
grow upscale enough to support increasing potential for damaging
wind gusts given the strong background flow. however, decreasing
buoyancy and weakening height falls with eastward extent should
gradually limit convective intensity into parts of the middle oh
valley late thursday evening.
..lyons.. 02/18/2026
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note: the next day 2 outlook is scheduled by 0700z