SPC AC 290600

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0100 AM CDT Mon Jun 29 2020

   Valid 301200Z - 011200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
   THE DAKOTAS AND INTO NEBRASKA...

   ...SUMMARY...
   Strong/locally severe storms will be possible across portions of the
   northern and central Plains on Tuesday.

   ...Synopsis...
   An upper low over the Northeast is forecast to remain in place
   Tuesday, while a vigorous, short-wave component of the
   larger/longer-wavelength western U.S. trough pivots northeastward in
   a negatively tilted manner into/across the central and northern
   Plains states.  In between these two features, stout ridging will
   prevail from central Canada and the Upper Great Lakes to the
   southern Plains.

   At the surface, a cool frontal surge is expected across the northern
   Plains in tandem with the upper trough advance.  Meanwhile, a
   surface low will remain across Kansas, along the western portion of
   a weak/wavy frontal zone extending east-southeastward to the
   Carolinas through the period.

   ...The Dakotas and Nebraska, and vicinity...
   Storms may be ongoing at the start of the period over the eastern
   Montana/western North Dakota region, possibly with some
   local/accompanying severe potential.  As the front/trough advances
   eastward ahead of the northeastward-pivoting upper system, some
   breaches in the cap are expected, leading to scattered afternoon
   storm development near the front over the Dakotas, within a
   substantially destabilized airmass.  While flow aloft will remain
   unidirectional/south-southeasterly, and the strongest of which will
   remain well behind the surface front, shear will be sufficient for
   the developing storms to organize and grow upscale into bands, with
   large hail and damaging winds the primary severe risks.  

   Storms may increase/develop southward into the Mid Missouri Valley
   region during the evening, along with attendant/local severe
   potential.  This threat is expected to persist through the evening,
   and possibly into the overnight hours, before storms gradually
   diminish.
   ...Mid MS/lower OH valleys to the Carolinas...
   As an upper low lingers over the Northeast, a persistent/broad band
   of moderate west-northwesterly cyclonic flow will remain in place
   from the Ohio Valley across the Mid South/Southeast.  As
   multiple/subtle disturbances/vorticity maxima pivot through the flow
   field, another day of scattered, east-southeastward moving
   storms/bands of storms is expected.  While the magnitude of the low-
   to mid-level flow should remain generally in the 20 to 30 kt range,
   a few of the stronger storms/storm clusters will likely produce
   locally gusty winds with some possible tree damage.  Severe risk
   should diurnally peak in the afternoon/early evening hours, though
   storms -- and lingering/local severe risk -- may continue well into
   the evening.

   ..Goss.. 06/29/2020

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