ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 170901
   SPC AC 170901

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0401 AM CDT Tue Jun 17 2025

   Valid 201200Z - 251200Z

   ...DISCUSSION...
   ...D4/Friday...
   A surface cyclone is forecast to deepen over the northern/central
   High Plains on Friday, as a mid/upper-level trough shifts gradually
   eastward across the western CONUS. Strong to extreme buoyancy will
   develop by afternoon across parts of the central/northern Plains,
   along/south of an effective warm front that will extend east of the
   surface low. Much of the warm sector will likely remain capped, but
   isolated storm development will be possible by late afternoon
   near/north of the warm front, with increasing storm coverage during
   the evening in response to a strengthening low-level jet. Supercells
   will be possible initially, though the pattern suggests potential
   for an MCS to develop and move eastward Friday night across the
   upper Great Lakes vicinity. 

   Guidance continues to vary substantially regarding the most favored
   corridor for an organized severe threat. For example, the GFS/GEFS
   is farther north across ND/northern MN, while the ECMWF/ECENS is
   farther south across central MN/northern WI. Severe probabilities
   will eventually be needed for this scenario, but confidence is the
   favored corridor is too low for a 15% area.  

   Strong to severe storms may also develop across the northern Rockies
   and spread eastward across MT, in association with the approaching
   mid/upper-level trough. Probabilities will likely be needed for this
   scenario in future outlooks, though confidence is too low for a 15%
   area at this time. 

   ...D5/Saturday...
   A similar surface pattern is expected over the Great Plains and
   upper Midwest on Saturday compared to D4/Friday. However, an
   amplifying upper ridge may tend to suppress storm development
   through much of the period. Some severe potential may again evolve
   across MT along the northwest periphery of the ridge. There may also
   be some potential for strong to severe storms along the northeast
   periphery of the ridge into parts of the lower Great Lakes and New
   England. 

   ...D6/Sunday - D8/Tuesday...
   An upper-level ridge will remain prominent through the weekend into
   early next week across parts of the central/eastern CONUS. Strong to
   severe storms and possible MCS development could continue to occur
   along the periphery of the ridge, but predictability becomes quite
   low at this range regarding the details of any organized threat.

   ..Dean.. 06/17/2025

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