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Storm Prediction Center Outlooks - Days 4 - 8

<Day 3 Outlook
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Day 4-8 Outlook
Day 4 - 8 Outlook
D4Sat January 20th 2018 - Sun January 21st 2018 D7Tue January 23rd 2018 - Wed January 24th 2018
D5Sun January 21st 2018 - Mon January 22nd 2018 D8Wed January 24th 2018 - Thu January 25th 2018
D6Mon January 22nd 2018 - Tue January 23rd 2018 (All days are valid from 12 UTC - 12 UTC)

Note: A severe weather area depicted in the Day 4-8 period indicates a 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 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

 Convective Outlook Discussion - Day 4-8
   ACUS48 KWNS 170920
   SPC AC 170920

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

   Valid 201200Z - 251200Z

   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


NWS Storm Prediction Center Day 4-8 Outlook