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Jul 19, 2018 1730 UTC Day 2 Convective Outlook
Updated: Thu Jul 19 17:36:03 UTC 2018 (Print Version | 20180719 1730Z Day 2 shapefile | 20180719 1730Z Day 2 KML)
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 Forecast Discussion

   SPC AC 191736

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1236 PM CDT Thu Jul 19 2018

   Valid 201200Z - 211200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR SOUTHERN
   IL/IN...CENTRAL/WESTERN KY...MIDDLE/WESTERN TN...NORTHERN MS/AL...

   ...SUMMARY...
   Scattered severe thunderstorms associated with large hail, wind
   damage and a tornado threat will be possible Friday afternoon and
   evening across parts of the MIssissippi, Ohio and Tennessee Valleys.

   ...Synopsis...
   An anomalously strong deep layer trough and associated surface
   cyclone are expected to move southeastward from the upper Midwest
   into portions of the lower Great Lakes on Friday. The surface
   pattern will be complicated by one or more convectively-induced
   outflow boundaries, with a synoptic-scale surface trough/cold front
   expected to progress eastward south of the surface low through the
   period. A stout EML will spread eastward from the southern Plains
   over rich low-level moisture, resulting in a volatile thermodynamic
   environment developing over portions of the MS/TN/OH River Valleys
   and the Midwest. 

   ...MS/TN/OH River Valleys into the Midwest...
   A potentially significant severe thunderstorm episode is possible
   across portions of the MS/TN/OH Valleys and the Midwest on Friday,
   though considerable uncertainty remains regarding convective
   evolution through the period. 

   One or more clusters of convection will likely be ongoing Friday
   morning, though the remnants of these clusters are expected to push
   east through the day, allowing for moderate-to-strong
   destabilization in their wake. The strongest focus for convection
   will be the surface trough moving through IL/IN/OH, though this area
   will be somewhat removed from the stronger shear and instability,
   especially with northward extent. 

   Foci for convective initiation will be more subtle further south and
   west, but the environment will also be much more volatile, with
   strong instability (MLCAPE of 2500-4000 J/kg possible) and effective
   shear (45-60 kt) in place. Scattered thunderstorms are expected to
   develop during the afternoon, potentially along the trailing surface
   boundary and also evolving out any early day elevated convection.
   Initially discrete storm modes will favor large hail (potentially
   greater than 2 inches in diameter), along with damaging wind gusts
   and a tornado or two. With time, evolution into one or more
   upscale-growing clusters is expected into the evening. Any such
   clusters would be capable of producing damaging wind swaths as they
   propagate to the southeast. 

   ...Southern/Central Plains...
   Confidence in convective initiation is much lower across portions of
   northwest AR westward into northern OK and southern KS. However,
   very strong heating in the presence of a weak surface boundary may
   support isolated development during the afternoon. Additionally,
   there is some potential for elevated convection to develop across
   this region, either early or late in the period. Given the very
   favorable instability/shear environment across this region, a
   conditional risk of severe hail and wind will be present across this
   area.

   ...MAXIMUM RISK BY HAZARD...
   Tornado:   5%     - Slight
   Wind:     30%     - Enhanced
   Hail:     30% SIG - Enhanced

   ..Dean/Dial.. 07/19/2018

   CLICK TO GET WUUS02 PTSDY2 PRODUCT

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

        
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Page last modified: July 19, 2018
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