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< Day 3 Outlook    
Day 4-8 Severe Weather Outlook Issued on Aug 2, 2021
Updated: Mon Aug 2 08:41:03 UTC 2021
D4-8 D4 D5 D6 D7 D8
 Pop.  Cities  CWAs  RFCs  Interstates  Counties  ARTCC  FEMA  Tribal

D4Thu, Aug 05, 2021 - Fri, Aug 06, 2021 D7Sun, Aug 08, 2021 - Mon, Aug 09, 2021
D5Fri, Aug 06, 2021 - Sat, Aug 07, 2021 D8Mon, Aug 09, 2021 - Tue, Aug 10, 2021
D6Sat, Aug 07, 2021 - Sun, Aug 08, 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 020839
   SPC AC 020839

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0339 AM CDT Mon Aug 02 2021

   Valid 051200Z - 101200Z

   On Thu/D4, a dwindling upper low will move from the upper OH Valley
   into NY, with 35-40 kt 500 mb winds across the Mid Atlantic. At the
   surface, a weak low will move roughly from NC toward the Delmarva as
   a warm front lifts north across NJ and into southern New England.
   While ample moisture will be available for storms, significant
   precipitation is expected through the period, and shear will be
   marginal. While isolated strong to severe storms cannot be ruled
   over parts of the Mid Atlantic, potential remains too low.

   During the Fri/D5 to Sat/D5 time frame, a weakening shortwave trough
   is forecast to move from the northern High Plains to the upper MS
   Valley, with low pressure developing over SD and moving into MN.
   Storms appear most likely Friday evening in a zone of warm advection
   from the Dakotas into MN, with marginal instability forecast. Storms
   are expected to persist through Sat/D5 into MN and WI as moisture
   and instability continue to increase. While there is potential for a
   few severe storms in this regime, the weakening wave decreases

   Behind this lead wave, a stronger shortwave trough is forecast to
   affect the northern Plains and upper MS Valley during the Sun/D7 to
   Mon/D8 period. Although predictability is low, this type of pattern
   may result in severe storms, as persistent southerly low-level winds
   bring a return of upper 60s and lower 70s F dewpoints to the region.
   Strong instability may develop, and the Dakotas, MN and WI remain an
   area of interest. If model trends persist, severe risk areas may be
   added in later outlooks.

   ..Jewell.. 08/02/2021


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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