Day 1 Outlook Day 2 Outlook Day 3 Outlook Days 4-8 Outlook

Day 4-8 Outlook
Day 4 - 8 Outlook
Day 4-8 Severe Weather Outlook. A depicted severe weather area indicates a 30% or higher probability for severe thunderstorms within 25 miles of a point.
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)
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. 1) large differences in the deterministic model solutions,
  2. 2) large spread in the ensemble guidance, and/or
  3. 3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears highly unlikely during the entire period (e.g. less than a 30% probability for a regional severe storm area across the CONUS through the entire Day 4-8 period).

Images courtesy of the NWS Storm Prediction Center
 Forecast Discussion


000
ACUS48 KWNS 160847
SWOD48
SPC AC 160846

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

Valid 191200Z - 241200Z

...DISCUSSION...
...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
considerable.

...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