SPC AC 170045

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0745 PM CDT Thu Jul 16 2020

   Valid 170100Z - 171200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS WESTERN AND
   CENTRAL NEBRASKA...

   ...SUMMARY...
   Large hail and damaging winds will also be possible through the
   evening across west-central Nebraska. A lingering threat for hail
   and damaging wind gusts will persist for another hour or two across
   western New York and western Pennsylvania.

   ...01Z Outlook Update...
   The outlook has been updated based on latest convective trends.  A
   limited severe risk continues across southwestern New York State and
   areas of western Pennsylvania, where a few storms may briefly
   acquire rotation and produce wind/hail and perhaps a tornado.  Ref
   MCD 1244 for more details.  Overall convective trends indicate
   continued weakening in tandem with loss of surface
   heating/instability.  Overturning has also occurred southwestward
   from West Virginia into northeastern Arkansas, where severe
   probabilities were removed for this update.

   A limited risk of hail and damaging wind gusts continues across
   southern Missouri and northern Arkansas, where recent satellite
   imagery indicates redevelopment and objective analyses indicate a
   strongly unstable airmass in place.  Additional redevelopment
   upstream is indicated by a few CAMs, although this scenario is
   uncertain.  Any severe threat should be isolated, however, and weak
   shear should limit convective organization as well.  Marginal (5%)
   probabilities for hail/wind remain in place for this scenario.

   So far, the severe threat in northern Minnesota has remained
   relatively isolated, though lift associated with 1) a surface trough
   migrating through the region and 2) a mid-level shortwave over
   southwestern Ontario should continue to support isolated convection
   through dark or slightly after.  Given shear profiles (which are
   appreciable with respect to vertical shear), convection may remain
   organized and pose an isolated severe risk for the next couple of
   hours or so.

   A few CAMs remain optimistic in developing a cluster of storms in
   western Nebraska, and this may materialize given strong buoyancy and
   northeastward-moving convection out of northeastern Colorado that
   may encourage new updrafts along its leading edge.  Marginal and
   Slight risk areas (and attendant probabilities) remain in place for
   this update.

   ..Cook.. 07/17/2020

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