SPC AC 260726

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0226 AM CDT Fri Jun 26 2020

   Valid 281200Z - 291200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF THE NORTHEAST AND VICINITY...AND OVER PORTIONS OF THE ROCKIES AND
   NORTHERN HIGH PLAINS...

   ...SUMMARY...
   A few severe storms are expected across portions of the Northeast
   and Ohio Valley into the central Appalachians and Mid Atlantic
   region on Sunday.  Isolated stronger storms and local severe
   potential is also expected from the Wyoming vicinity into the
   northern High Plains.

   ...Synopsis...
   Amplification of the upper flow field over the U.S. will continue
   Day 3 (Sunday June 28), as an upper low/trough continues to dig
   southward across the western U.S. through the period.  In response
   downstream amplification will also continue -- both with ridging
   over central NOAM, and with the eastern Canada/eastern U.S. upper
   low/trough.  

   At the surface, a generally weak pattern with subtle baroclinic
   zones is expected, though a pronounced cold front will remain in
   place from the northern High Plains southwestward across the
   Intermountain West through the period.

   ...The Ohio Valley/Northeast, south across Virginia...
   A belt of moderate northwesterly mid-level flow is progged across
   portions of the Northeast and into the upper Ohio Valley/central
   Appalachians/Mid Atlantic region, with several small-scale
   disturbances moving through the broader cyclonic flow field.  A very
   weak surface trough/front will likewise move southeastward across
   this region, helping to foster scattered afternoon storm development
   as modest diurnal destabilization occurs.  

   While specific areas of potentially greater risk may evolve, at this
   time will introduce a broad 5%/MRGL risk to cover an
   apparent/background threat for locally gusty/damaging winds with
   southeastward-moving storms/storm clusters.

   ...Northeast Idaho to eastern Montana and the western Dakotas...
   As the upper low digs southward across the West, enhanced
   southwesterly flow aloft will be maintained from portions of the
   Rockies and northern High Plains.  Beneath this belt of flow, very
   slow-moving cold front will linger, likely aiding in development of
   at least isolated afternoon storms.  With the strength of the
   mid-level flow contributing to ample shear for organized storms,
   risk for locally damaging wind gusts is evident, along with some
   hail potential into the northern High Plains where CAPE is expected
   to be a bit greater than areas farther west.

   ...Central Plains vicinity...
   A weak warm front is progged to lie across the central Plains
   vicinity during the day, lifting slowly northward with time.  While
   under the influence of broad upper ridging, weak disturbances on the
   eastern fringe of cyclonic flow associated with the digging western
   trough are expected to traverse the Plains.  Though models differ
   with respect to timing/location of these features, as well as with
   the location of the surface front, a localized area of severe
   potential could evolve during the afternoon and evening.  At this
   time, an area will not be highlighted due to uncertainty.  However,
   a low-probability risk area may require introduction in later
   forecasts.

   ..Goss.. 06/26/2020

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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z