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    Day 2 Outlook >
Aug 23, 2017 0600 UTC Day 1 Convective Outlook
Updated: Wed Aug 23 04:59:42 UTC 2017 (Print Version | 20170823 1200Z Day 1 shapefile | 20170823 1200Z Day 1 KML)
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 Forecast Discussion
   SPC AC 230459

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1159 PM CDT Tue Aug 22 2017

   Valid 231200Z - 241200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
   AND EVENING ACROSS THE SOUTHERN MID-ATLANTIC COAST REGION AND
   EASTERN CAROLINAS...

   ...SUMMARY...
   A few strong to severe storms may impact parts of the southern
   Mid-Atlantic region and eastern Carolinas this afternoon and
   evening. Gusty, damaging winds will be the main threat.

   ...Synopsis...
   A mid-upper level closed low will track northeast across Quebec
   through tonight, while a shortwave trough digs southeast from
   central Canada toward the Upper Great Lakes region this forecast
   period.  This latter system will aid in maintaining a large-scale
   trough across much of the Great Lakes, OH Valley into the Northeast
   and Mid-Atlantic states, with weak height falls expected across VA
   and Carolinas.  At the surface, an area of low pressure will track
   across southern to eastern Quebec.  The trailing cold front should
   extend through eastern New England to off the northern Mid-Atlantic
   coast to central VA, the western Carolinas and into the central Gulf
   Coast states at 12Z today.  This boundary will advance toward the
   Southeast U.S. and Gulf Coasts, while the northern extent should
   clear much of New England by early afternoon. 

   ...Southeast VA and the eastern Carolinas...
   The air mass south of the approaching cold front today remains quite
   moist (precipitable water values at or above 2 inches per 00Z
   soundings).  Despite weak mid-level lapse rates, the abundant
   moisture and surface heating will contribute to the occurrence of
   moderate instability (MLCAPE 1000-2000 J/kg).  This combined with
   effective bulk shear of 25-30 kt suggests multicell storms/clusters
   should be the primary storm mode, with some potential for upscale
   growth as storms merge and/or cold pools develop.  A weak mid-level
   impulse is expected to shift east from the southern Appalachians
   this morning, reaching southeast VA and the eastern Carolinas by
   peak heating.  Forcing for ascent attendant to this impulse should
   aid in thunderstorm development, with convection forming across the
   higher terrain, and along the cold front and a pre-frontal trough. 
   Steepening low-level lapse rates and the available moderate
   instability should prove sufficient in supporting locally strong to
   damaging winds with the stronger/sustained storms this afternoon and
   evening.

   ..Peters/Gleason.. 08/23/2017

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z

        
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Page last modified: August 23, 2017
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