NWS Storm Prediction Center - Day 4-8 Convective Outlook

Day 4-8 Severe Weather Outlook Issued on May 12, 2021
Updated: Wed May 12 08:36:04 UTC 2021
D4-8 D4 D5 D6 D7 D8
 Pop.  Cities  CWAs  RFCs  Interstates  Counties  ARTCC  FEMA  Tribal


D4Sat, May 15, 2021 - Sun, May 16, 2021 D7Tue, May 18, 2021 - Wed, May 19, 2021
D5Sun, May 16, 2021 - Mon, May 17, 2021 D8Wed, May 19, 2021 - Thu, May 20, 2021
D6Mon, May 17, 2021 - Tue, May 18, 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

   ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 120834
   SPC AC 120834

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0334 AM CDT Wed May 12 2021

   Valid 151200Z - 201200Z

   ...DISCUSSION...
   A closed upper low should move slowly eastward across CA, the Great
   Basin, and Southwest this upcoming weekend. This feature is forecast
   to eventually eject east-northeastward across the southern/central
   Plains early next week, but there are some timing differences in
   medium-range guidance regarding when this may occur. Low-level
   moisture should gradually increase across the southern/central
   Plains through the weekend and into early next week. Still, the
   severe threat across these areas will probably remain rather limited
   owing to weak mid-level flow and related deep-layer shear on both
   Day 4/Saturday and Day 5/Sunday. Depending on when the upper low
   evolves into an open wave and ejects across the southern/central
   Plains, some increase in the overall severe threat may occur around
   Day 6/Monday and/or Day 7/Tuesday as the mid-level flow strengthens.
   Regardless, there is too much uncertainty regarding the forecast
   evolution of the upper trough/low early next week to include 15%
   severe probabilities.

   ..Gleason.. 05/12/2021

   CLICK TO GET WUUS48 PTSD48 PRODUCT


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.

Data courtesy the Storm Prediction Center

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