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.
D4Tue, Sep 25, 2018 - Wed, Sep 26, 2018 D7Fri, Sep 28, 2018 - Sat, Sep 29, 2018
D5Wed, Sep 26, 2018 - Thu, Sep 27, 2018 D8Sat, Sep 29, 2018 - Sun, Sep 30, 2018
D6Thu, Sep 27, 2018 - Fri, Sep 28, 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 220752
SWOD48
SPC AC 220750

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0250 AM CDT Sat Sep 22 2018

Valid 251200Z - 301200Z

...DISCUSSION...
...Tuesday/Day 4...
The medium-range models including the ECMWF, GFS, UKMET and Canadian
move an upper-level trough from the southern and central Rockies
eastward into the Great Plains on Tuesday. A cold front is forecast
to move southeastward across the central Plains, mid to upper
Mississippi Valley and Great Lakes region. The ECMWF, GFS and
Canadian are in general agreement, developing convection along the
front from western Kentucky northeastward into Ohio. The models are
forecasting enough moisture, instability and shear for a severe
threat Tuesday afternoon where a 15 percent contour has been
maintained. The primary severe threats are expected to be hail and
damaging wind gusts.

...Wednesday/Day 5...
The medium-range models differ on the position of the cold front by
Wednesday afternoon. The ECMWF and Canadian solutions have the front
further east than the GFS which seems reasonable at this point.
Thunderstorm development will be possible along the front from the
northern Gulf Coast states northeastward into the central
Appalachian Mountains during the day on Wednesday. A marginal severe
threat would be possible Wednesday afternoon with hail and strong
gusty winds across the central Appalachians and in parts of the
Northeast.

...Thursday/Day 6 to Saturday/Day 8...
On Thursday and Friday, the models move the front southeastward
across the Southeast with the western end of the front in the
southern Plains. Thunderstorms will again be possible along the
front during the day on Thursday and Friday but severe thunderstorms
appear unlike due to minimal amount of deep-layer shear. On
Saturday, some moisture advection is forecast to take place in the
southern and central Plains as a warm front lifts northward across
the region. Thunderstorms will be possible along this front if this
scenario materializes but confidence is low concerning where the
position of the front will be and how many storms will form.
Thunderstorms will also be possible eastward along a slow-moving
front into part of the Southeast Saturday afternoon.

..Broyles.. 09/22/2018