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< Day 3 Outlook    
Day 4-8 Severe Weather Outlook Issued on Sep 17, 2021
Updated: Fri Sep 17 08:45:03 UTC 2021
D4-8 D4 D5 D6 D7 D8
 Pop.  Cities  CWAs  RFCs  Interstates  Counties  ARTCC  FEMA  Tribal

D4Mon, Sep 20, 2021 - Tue, Sep 21, 2021 D7Thu, Sep 23, 2021 - Fri, Sep 24, 2021
D5Tue, Sep 21, 2021 - Wed, Sep 22, 2021 D8Fri, Sep 24, 2021 - Sat, Sep 25, 2021
D6Wed, Sep 22, 2021 - Thu, Sep 23, 2021 (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 170842
   SPC AC 170842

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0342 AM CDT Fri Sep 17 2021

   Valid 201200Z - 251200Z

   Modestly amplified mid-level troughing is forecast to progress east
   of the northern Rockies early next week, and may undergo further
   amplification while slowly continuing across and east of the
   Mississippi Valley through the middle to latter portion of next
   week.  As it does, it appears that a fairly significant surface cold
   front may surge out ahead of the stronger mid-level cold pool and
   forcing for ascent, and the most prominent surface cyclogenesis may
   occur near/east of the James/Hudson Bay vicinity.  A remnant plume
   of warm elevated mixed-layer air probably will be eroded/overturned
   across the Great Plains, and generally weak destabilization (at
   least where stronger shear and forcing for ascent become focused)
   probably will be a mitigating factor concerning the risk for severe
   weather.  While thunderstorms posing at least some risk for severe
   weather may be possible along/ahead of the front, the overall severe
   weather potential appears relatively low at this time.

   ..Kerr.. 09/17/2021


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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Page last modified: September 17, 2021
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