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Day 4-8 Severe Weather Outlook Issued on Jan 17, 2017
Updated: Tue Jan 17 09:59:03 UTC 2017
Day 4-8 Severe Weather Outlook Graphics Issued on Jan 17, 2017
Day 4 Severe Weather Outlook Graphics Issued on Jan 17, 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 Jan 17, 2017
Day 5 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 75,277 6,564,023 New Orleans, LA...Baton Rouge, LA...Mobile, AL...Jackson, MS...Metairie, LA...
Day 6 Severe Weather Outlook Graphics Issued on Jan 17, 2017
Day 6 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 73,124 5,041,712 Montgomery, AL...Mobile, AL...Columbus, GA...Tallahassee, FL...Albany, GA...
Day 7 Severe Weather Outlook Graphics Issued on Jan 17, 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 Jan 17, 2017
Day 8 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
D4Fri, Jan 20, 2017 - Sat, Jan 21, 2017 D7Mon, Jan 23, 2017 - Tue, Jan 24, 2017
D5Sat, Jan 21, 2017 - Sun, Jan 22, 2017 D8Tue, Jan 24, 2017 - Wed, Jan 25, 2017
D6Sun, Jan 22, 2017 - Mon, Jan 23, 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 170957
   SPC AC 170957

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0357 AM CST Tue Jan 17 2017

   Valid 201200Z - 251200Z

   ...DISCUSSION...
   The medium range models including the ECMWF and GFS solutions begin
   the day 4 to 8 period with a negatively tilted upper-level trough
   over the eastern Gulf Coast States and move this feature
   northeastward into the Mid-Atlantic on Friday/Day 4. The models
   suggest that moisture advection will take place across the western
   and central Gulf Coast States on Friday into Friday night. A severe
   threat appears possible Friday night in the lower Mississippi Valley
   and central Gulf Coast States although uncertainty is increased due
   to instability and timing concerns. On Saturday/Day 5, both the
   ECMWF and GFS show an impressive 90 to 110 kt mid-level jet moving
   through northern Mexico. The exit region of the mid-level jet is
   forecast to spread eastward across the lower Mississippi Valley on
   Saturday over the top of strong moisture advection. The exit region
   of the mid-level jet will create strong deep-layer shear profiles
   and enhance broadscale lift being supportive of supercells and
   organized line segments. This potential for severe storms is
   forecast to continue into Sunday/Day 6 as the core of the mid-level
   jet moves into the western Gulf of Mexico and influence of the jet
   spreads eastward across the Gulf Coast region. GFS forecast
   soundings early Sunday at Mobile, AL show moderate instability, 0-6
   km shear of 50 to 55 kt and unseasonably mid-level steep lapse rates
   suggesting a significant severe threat along with a threat for
   tornadoes, wind damage and large hail will be possible with this
   system. The main uncertainty is the timing of the system. The
   current model solutions have slowed the mid-level jets eastward
   progression by about 9 hours suggesting a starting point for the
   event further to the west on Saturday. It appears that the greatest
   severe weather impact could occur on Sunday when a higher end severe
   weather episode will be possible. A 30 percent contour could be
   added once certainty increases concerning the timing of the system.
   On Monday/Day 7, both the ECMWF and GFS solutions move the
   upper-level system into the eastern states and push the warm sector
   into the Atlantic. If the system ends up being slower than is
   currently forecast, then a chance for severe storms could exist
   along the Atlantic seaboard early on Monday. The current solutions
   suggest severe thunderstorms will be unlikely across the continental
   United States on Tuesday/Day 8.

   ..Broyles.. 01/17/2017

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Page last modified: January 17, 2017
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