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Apr 29, 2017 1730 UTC Day 2 Convective Outlook
Updated: Sat Apr 29 17:32:00 UTC 2017 (Print Version | 20170429 1730Z Day 2 shapefile | 20170429 1730Z Day 2 KML)
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 Forecast Discussion

   SPC AC 291732

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1232 PM CDT Sat Apr 29 2017

   Valid 301200Z - 011200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM MISSISSIPPI
   AND ALABAMA NORTHWARD INTO THE LOWER OHIO VALLEY...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
   GULF COAST NORTHWARD INTO THE MIDDLE MISSISSIPPI VALLEY AND SOUTHERN
   GREAT LAKES...

   ...SUMMARY...
   Severe thunderstorms will be possible across portions of the
   lower/mid Mississippi Valley eastward to Alabama Sunday into Sunday
   night. Damaging winds will likely be the primary threat, but a few
   tornadoes may also be possible.  A couple strong/severe storms may
   also occur Sunday over parts of the Ohio Valley and southern Great
   Lakes.

   ...Synopsis...
   A large mid-level closed low will lift northeast from the
   southern/central High Plains to the Midwest, as a shortwave trough
   rotates around its periphery from Texas into the Ohio Valley. In
   turn, expansive cyclonic flow aloft should establish over much of
   the contiguous US on Sunday.

   ...Portions of the mid/lower Mississippi Valley and eastward...
   With such an amplified system and strong meridional flow aloft,
   multiple areas of convection will likely be ongoing Sunday morning. 
   The main influencing factor regarding timing and location of
   potential severe weather will be with one or more north-south
   oriented bands of storms across parts of the lower/mid Mississippi
   Valleys, likely in advance of the surface cold front.  The latest
   convection-allowing model guidance converges towards a scenario with
   the placement of a north to south oriented squall line at 30/12z
   located from western TN/eastern AR south into northern LA and
   southwestern LA.  A squall line is forecast to continue eastward
   across the lower Mississippi Valley into AL where a moisture-rich
   airmass will support moderate buoyancy.  Despite the presence of
   enlarged low-level hodographs, a linear convective mode
   (nonsupercell) is forecast and will likely limit the overall tornado
   risk.  Additionally, 0-3 km shear vectors with respect to projected
   line segment motion will be suboptimal for a heightened mesovortex
   tornado risk, although the moist low levels may support some
   low-tornado threat.  Strong to severe gusts capable of wind damage
   are forecast to be the primary severe hazard and could concentrate
   primarily near LEWP/bowing structures in the QLCS.  This band is
   forecast to gradually weaken with eastward extent as it outpaces
   large-scale ascent and encounters increasing inhibition. Behind
   these storms, uncertainty exists with the potential for
   re-development of convection along the front (due to prior
   convective overturning). 

   Across the mid Mississippi Valley, a highly conditional risk for
   severe weather is apparent owing to destabilization concerns via
   widespread convection from both clouds/early-day precip and
   widespread thunderstorms located to the south during the morning. 
   If strong updrafts manage to develop coincident with peak heating,
   storms within a portion of this region may yield a localized
   wind/tornado risk before diminishing in intensity during the early
   evening.  

   ...Portions of northern OH into northwest PA...
   Modest warm advection in the vicinity of lift from a west-east warm
   frontal zone over the area may result in isolated storms during the
   afternoon.  A couple of locally strong storms may yield the risk for
   isolated marginally severe hail/damaging winds.

   ..Smith.. 04/29/2017

   CLICK TO GET WUUS02 PTSDY2 PRODUCT

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z

        
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Page last modified: April 29, 2017
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