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Day 4-8 Severe Weather Outlook Issued on Sep 27, 2017
Updated: Wed Sep 27 08:59:03 UTC 2017
Day 4-8 Severe Weather Outlook Graphics Issued on Sep 27, 2017
Day 4 Severe Weather Outlook Graphics Issued on Sep 27, 2017
Day 4 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 5 Severe Weather Outlook Graphics Issued on Sep 27, 2017
Day 5 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 6 Severe Weather Outlook Graphics Issued on Sep 27, 2017
Day 6 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 7 Severe Weather Outlook Graphics Issued on Sep 27, 2017
Day 7 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 8 Severe Weather Outlook Graphics Issued on Sep 27, 2017
Day 8 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
D4Sat, Sep 30, 2017 - Sun, Oct 01, 2017 D7Tue, Oct 03, 2017 - Wed, Oct 04, 2017
D5Sun, Oct 01, 2017 - Mon, Oct 02, 2017 D8Wed, Oct 04, 2017 - Thu, Oct 05, 2017
D6Mon, Oct 02, 2017 - Tue, Oct 03, 2017 (All days are valid from 12 UTC - 12 UTC the following day)
Note: A severe weather area depicted in the Day 4-8 period indicates 15%, 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 unlikely (i.e., less than 15%) for the forecast day.
 Forecast Discussion

   ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 270857
   SPC AC 270857

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0357 AM CDT Wed Sep 27 2017

   Valid 301200Z - 051200Z

   ...DISCUSSION...
   Medium-range models continue to exhibit increasingly divergent
   solutions with time through the medium-range period, suggestive of
   issues with predictability in the evolving weather pattern across
   the U.S. days 4-8.  Basic/large-scale similarities are noted between
   the GFS and ECMWF Day 4 (Saturday 9-30), as a trough moves off the
   northeast U.S./Mid-Atlantic coasts, and a second/larger trough
   expands across the West.

   However, the expansion/evolution of this western U.S. trough differs
   increasingly with time through Days 5-6, such that by the beginning
   of Day 7 (Tuesday 10-3), differences are quite substantial.

   Depending upon evolution/advance of the western trough with time,
   and possible passage of an associated cold front through the Plains
   roughly Day 5 (Sunday 10-1), some severe risk could evolve over the
   central Plains vicinity.  At this time however, confidence regarding
   pattern evolution remains too low to warrant introduction of any
   risk areas.

   ..Goss.. 09/27/2017

   CLICK TO GET WUUS48 PTSD48 PRODUCT
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Page last modified: September 27, 2017
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