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Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0227 AM CDT Wed Sep 14 2022

Valid 161200Z - 171200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE UPPER MIDWEST AND CENTRAL HIGH PLAINS...

...SUMMARY...
Isolated severe thunderstorms are possible across portions of the
Upper Midwest and Central High Plains on Friday.

...Synopsis...
Broadly cyclonic flow is forecast to be in place over the western
CONUS early Friday, with a corridor of modestly enhanced mid-level
flow stretching from southern CA across the central Plains and into
the upper/mid MS Valley. A lead shortwave trough embedded within
this corridor is expected to move into the Upper Midwest, with
another shortwave following in its wake from the Great Basin across
the central Rockies into the northern High Plains.

...Upper Midwest...
Surface low attendant to the lead shortwave trough mentioned in the
synopsis is forecast to be over southwestern MN early Friday
morning. This low is expected to shift eastward in tandem with its
parent shortwave, moving into northwest WI by Friday night. Strong
southerly surface winds will precede this low, facilitating
increased convergence along both the cold front and warm front.
Buoyancy will be tempered by widespread cloud cover and poor lapse
rates, but thunderstorms are still expected to develop within the
warm sector. Veering low-level winds with height may support
isolated strong to severe storms capable of producing a damaging
gust and/or brief tornado.

...Central High Plains...
Lee troughing is forecast to deepen across the High Plains ahead of
the second shortwave trough mentioned in the synopsis, with surface
cyclogenesis possible near the WY/SD/NE border intersection by
Friday evening. Southeasterly upslope flow is expected from central
Plains into this developing surface low, acco*panied by modest
low-level moisture advection. These southeasterly surface winds will
exist beneath moderate westerly flow aloft, resulting in 30 to 40 kt
of effective bulk shear across the region. 

Late afternoon thunderstorm development is possible along the lee
trough, particularly near the deepening low over eastern WY.
Eastward storm motion would take these storms into the more buoyant
air mass over NE during the evening, with the potential for
additional storm development in this region as well. Isolated
supercells are possible within this environment, with damaging gusts
and hail as the primary threat. Potential exists for upscale growth
and the development of forward-propagating convective line, but
uncertainties regarding mesoscale details limit predictability at
this forecast range.

..Mosier.. 09/14/2022