SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Wed Sep 14 2022
Valid 141200Z - 151200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM WESTERN NE
INTO CENTRAL/EASTERN SD...
...SUMMARY...
Storms capable of isolated severe gusts will be possible this
afternoon and evening from western Nebraska into parts of South
Dakota.
...Synopsis...
A broad mid/upper-level trough will persist over the western CONUS
today. Multiple embedded vorticity maxima within the longwave trough
are forecast to emerge over the Great Plains through the period, as
a downstream upper ridge shifts slowly eastward toward the
lower/mid-MS Valley. A surface cyclone is forecast to move slowly
eastward from Montana into the Dakotas, with a lee trough extending
southward into the central/southern High Plains, and a warm front
extending eastward toward the eastern Dakotas and central/northern
MN.
...Parts of the central/northern Plains...
Rather strong diurnal heating is expected across parts of the
central/northern Plains, along/east of the lee trough and
along/south of the warm front. Modest moisture return will support
the development of weak to moderate buoyancy, with MLCAPE increasing
into the 500-1500 J/kg range by late afternoon. Widely scattered
thunderstorms will be possible along the lee trough, and also
farther east from north-central NE into central/eastern SD, along
the leading edge of deeper returning moisture. While deep-layer
shear will likely remain relatively weak, inverted-v profiles and
increasing low-level flow will support a threat of isolated
severe/damaging gusts, even if convection remains relatively
disorganized.
Elevated convection may expand in coverage later tonight across
parts of ND/MN. Steep midlevel lapse rates could support an isolated
hail threat with this activity, but confidence in this scenario is
too low to include late-period hail probabilities at this time.
...Southern High Plains...
Scattered thunderstorm development is expected near/east of the lee
trough into the southern High Plains. Isolated strong gusts will be
possible with these storms, but buoyancy and low-level flow are
expected to be somewhat weaker compared to areas farther north, and
the threat of severe gusts appears too low to extend wind
probabilities into the region at this time.
..Dean/Weinman.. 09/14/2022
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