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.
D4Wed, May 31, 2017 - Thu, Jun 01, 2017 D7Sat, Jun 03, 2017 - Sun, Jun 04, 2017
D5Thu, Jun 01, 2017 - Fri, Jun 02, 2017 D8Sun, Jun 04, 2017 - Mon, Jun 05, 2017
D6Fri, Jun 02, 2017 - Sat, Jun 03, 2017 (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 270847
SWOD48
SPC AC 270846

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0346 AM CDT Sat May 27 2017

Valid 301200Z - 041200Z

...DISCUSSION...
...Tuesday/Day 4 and Wednesday/Day 5...
Both the ECMWF and GFS solutions move an upper-level trough across
the Upper Mississippi Valley on Tuesday and into the Ohio Valley on
Wednesday. Both models also maintain a broad moist sector from the
Texas Coastal Plains east-northeastward across the lower Mississippi
Valley into the Carolinas from Tuesday into Wednesday. Areas that
heat up the most along this corridor may develop a severe threat
mainly during the afternoon and evening for both days. Spatial
uncertainty is substantial at this point.

...Thursday/Day 6 to Saturday/Day 8...
Both the ECMWF and GFS develop strong moisture advection in the
Great Plains on Thursday but differ on how much instability will be
in place by Thursday afternoon. Both models show an upper-level
ridge over the high Plains which could dampen the severe threat
across much of the region in spite of the low-level moisture. The
models move the upper-level ridge eastward across the north-central
states on Saturday as an upper-level trough moves into the southern
High Plains. If this occurs, then severe thunderstorms would be
possible in the southern and central High Plains Saturday afternoon
especially if a dryline can develop. Uncertainty concerning the
spatial distribution is still substantial for Thursday and Friday.
The ECMWF and GFS solutions are quite different on Saturday
suggesting that predictability is very low late in the Day 4 to 8
period.

..Broyles.. 05/27/2017