NWS Storm Prediction Center - Day 4-8 Convective Outlook

Day 4-8 Severe Weather Outlook Issued on Jul 16, 2018
Updated: Mon Jul 16 08:48:02 UTC 2018
D4-8 D4 D5 D6 D7 D8
 Population  Cities  CWAs  Interstates  Counties  ARTCC  FEMA Regions

D4Thu, Jul 19, 2018 - Fri, Jul 20, 2018 D7Sun, Jul 22, 2018 - Mon, Jul 23, 2018
D5Fri, Jul 20, 2018 - Sat, Jul 21, 2018 D8Mon, Jul 23, 2018 - Tue, Jul 24, 2018
D6Sat, Jul 21, 2018 - Sun, Jul 22, 2018 (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 160846
   SPC AC 160846

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0346 AM CDT Mon Jul 16 2018

   Valid 191200Z - 241200Z

   ...Thursday/Day 4 and Friday/Day 5...
   The medium-range models move a shortwave trough into the upper
   Mississippi Valley on Thursday but agreement is not good even early
   in the day 4 to 8 period. The ECMWF and GFS are faster than the
   Canadian and UKMET solutions while the Parallel-FV3 is deeper and
   further south. The ECMWF and GFS solutions suggests the upper-level
   trough will not be phased-well with the area of greatest instability
   in the central Plains. In spite of this, isolated severe storms
   could still form behind the upper-level trough in the mid Missouri
   Valley but uncertainty is high due to model spread.

   On Friday, the models move the upper-level trough into the western
   Great Lakes and mid Mississippi Valley with moderate instability
   located in the base of the trough. Moderate deep-layer shear is also
   forecast in the mid Mississippi Valley where a severe threat will be
   possible late Friday afternoon into the evening. However,
   uncertainty concerning the timing of the upper-level trough is

   ...Saturday/Day 6 to Monday/Day 8...
   From Saturday to Monday, the models move the upper-level trough
   slowly eastward across the eastern U.S. Although moderate
   instability may develop each day across parts of the Southeast and
   along parts of the Atlantic Seaboard, deep-layer shear is forecast
   to be relatively weak. This would keep any severe threat marginal.
   Uncertainty concerning the trough timing reduces predictability for
   next weekend's forecast.

   ..Broyles.. 07/16/2018


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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