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< Day 3 Outlook    
Day 4-8 Severe Weather Outlook Issued on May 24, 2017
Updated: Wed May 24 09:03:02 UTC 2017
D4-8 D4 D5 D6 D7 D8
 Population  Cities  CWAs  Interstates  Counties  ARTCC  FEMA Regions

D4Sat, May 27, 2017 - Sun, May 28, 2017 D7Tue, May 30, 2017 - Wed, May 31, 2017
D5Sun, May 28, 2017 - Mon, May 29, 2017 D8Wed, May 31, 2017 - Thu, Jun 01, 2017
D6Mon, May 29, 2017 - Tue, May 30, 2017 (All days are valid from 12 UTC - 12 UTC the following day)
Note: A severe weather area depicted in the Day 4-8 period indicates 15%, 30% or higher probability for severe thunderstorms within 25 miles of any point.
PREDICTABILITY TOO LOW is used to indicate severe storms may be possible based on some model scenarios. However, the location or occurrence of severe storms are in doubt due to: 1) large differences in the deterministic model solutions, 2) large spread in the ensemble guidance, and/or 3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears unlikely (i.e., less than 15%) for the forecast day.
 Forecast Discussion

   ACUS48 KWNS 240901
   SPC AC 240901

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0401 AM CDT Wed May 24 2017

   Valid 271200Z - 011200Z

   Despite some differences on timing, latest GFS and ECMWF are
   generally consistent in the low-amplitude mid-level flow evolving
   into a broadly cyclonic flow regime at the beginning of the Day 4-8
   time frame. A very moist air mass will be in place from the
   central/southern Plains to the southeast states.

   ...Day 4/Saturday...
   A strongly unstable air mass will exist south of a frontal boundary
   that will likely extend from the southern Plains into the Ohio
   Valley Saturday afternoon. The MCS expected to move across portions
   of the central Plains on Day 3 may undergo diurnal intensification
   on Saturday as it moves east to the north of the boundary in the
   presence of strengthening mid-level flow and ascent with an
   approaching impulse. Such a scenario casts some uncertainty on
   downstream development as discrepancies are already noted with
   latest guidance regarding the position of the front. Nevertheless,
   it appears probable that additional development will occur near the
   front during the afternoon from the Ozarks southwest across eastern
   Oklahoma/northeast Texas, with more isolated development possible
   along the dryline extending into southwest Texas. Given a strongly
   sheared/unstable environment, supercell and linear storm modes are
   anticipated with all severe hazards possible, though details will
   depend on the evolution of the mesoscale influences with inherent
   low predictability at this time. Expanded/higher severe
   probabilities will likely be needed in subsequent outlooks. 

   ...Day 5/Sunday...
   A composite frontal boundary extending from the vicinity of the
   Great Lakes into central/southern Texas will serve as the focus for
   strong/severe thunderstorm development, with additional storms
   possible near a warm front from the Great Lakes into the
   mid-Atlantic region. Predictability regarding placement of 15
   percent coverage areas remains too low for this outlook. 

   ...Day 6/Monday and Beyond...
   Thunderstorms will once again develop along a weakening frontal
   boundary from New England south/west through Gulf Coast region and
   south Texas. Some severe risk will exist, though with continued low
   predictability at this extended time frame.

   ..Bunting.. 05/24/2017


To retrieve previous Day 4-8 convective outlooks, enter the date YYYYMMDD (e.g., 20050310 for March 10, 2005.)
Data available since March 8, 2005.
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