spc ac 171911
day 3 convective outlook
nws storm prediction center norman ok
0211 pm cdt sun may 17 2026
valid 191200z - 201200z
...there is a slight risk of severe thunderstorms from the great
lakes to the southern plains...
...summary...
widely scattered severe thunderstorms will be possible along a cold
front extending from the great lakes into the ohio valley and the
southern plains.
...great lakes and vicinity...
an ejecting midlevel trough over the upper ms valley early in the
period will begin to phase with the northern stream while moving
eastward over the great lakes. an associated surface cyclone will
move across southern on/qc, as a trailing cold front progresses
southeastward across the oh/middle ms valleys and into the southern
plains. convection will likely be ongoing at the start of the
period along the cold front from northwest tx and ok to the middle
ms valley and the vicinity of lake mi. the stronger low-midlevel
flow will be confined to the area closer to the great lakes, where
some diurnal destabilization could allow an uptick in threat for
wind damage and isolated large hail.
...lower oh valley into the southern plains...
farther southwest, flow aloft will be weaker and convection will be
tied to the slowing front and/or convective outflows from d2
convection persisting into d3. moderate to strong buoyancy (greater
to the west into tx) is expected just ahead of the front, which
combined with the relatively weak wind profiles, will favor
multicell clusters and line segments capable of producing occasional
wind damage and isolated large hail through the afternoon. there
will be some potential for an isolated supercell or two to move off
the serranias del burro into tx where large cape will coincide with
the cyclonic side of the subtropical jet and at least marginally
sufficient vertical shear. otherwise, the pattern will transition
overnight to a weak warm advection regime atop the cool air mass,
where elevated storms could produce large hail from northwest tx
into southern ok.
..thompson.. 05/17/2026
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