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.
D4Sat, Jan 20, 2018 - Sun, Jan 21, 2018 D7Tue, Jan 23, 2018 - Wed, Jan 24, 2018
D5Sun, Jan 21, 2018 - Mon, Jan 22, 2018 D8Wed, Jan 24, 2018 - Thu, Jan 25, 2018
D6Mon, Jan 22, 2018 - Tue, Jan 23, 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 170922
SWOD48
SPC AC 170920

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0320 AM CST Wed Jan 17 2018

Valid 201200Z - 251200Z

...DISCUSSION...
Despite some differences in timing/amplitude, medium-range guidance
is in relatively good agreement on the evolution of larger-scale
mid/upper features through the upcoming weekend. An amplified trough
will move ashore the southern California coast late this week;
thereafter, it will continue east across the Desert Southwest and
reach the southern/central Plains by D5/Sunday. Tied to this
mid-level progression, a deepening trough in the lee of the Rockies
will combine with a ridge centered over the Southeast to foster
southerly return flow across the eastern half of Texas this weekend.
Atop this moist sector, forcing for ascent and strengthening
mid/upper wind fields will aid the development of showers and
thunderstorms from southeast Texas to the Ozarks late Sunday into
the overnight hours. 

While the forecast kinematic profile would certainly favor a severe
threat (likely in the form of damaging winds and a few tornadoes),
both deterministic and ensemble data (primarily the ECMWF and its
ensemble) indicate substantive insolation and surface-based
destabilization remain quite uncertain. Therefore, the severe
potential currently remains too questionable for 15% probabilities
at this time. Nonetheless, at least some damaging-wind threat may
evolve, which would require probabilities in later outlooks.

This convective activity will then shift east towards the
central/eastern Gulf states through D6/Monday. However, guidance
suggests an even lower potential for inland destabilization across
this region. Thereafter, global guidance has trended towards a more
notable intrusion of dry air across the northern Gulf through
D8/Wednesday. In turn, the severe threat appears relatively low
through the remainder of the extended.

..Picca.. 01/17/2018