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Oct 18, 2018 1730 UTC Day 2 Convective Outlook
Updated: Thu Oct 18 17:18:51 UTC 2018 (Print Version | 20181018 1730Z Day 2 shapefile | 20181018 1730Z Day 2 KML)
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 Forecast Discussion

   SPC AC 181718

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1218 PM CDT Thu Oct 18 2018

   Valid 191200Z - 201200Z


   The risk for severe thunderstorms appears negligible across the U.S.
   Friday through Friday night.

   Within a belt of westerlies emanating from the mid-latitude Pacific,
   models indicate considerable amplification across the Pacific coast
   through eastern Canada and the U.S. during this period.  It appears
   that this will include a building large-scale ridge across parts of
   the northeast Pacific through the northern U.S. intermountain region
   and Rockies, into the Canadian Prairies, with larger-scale troughing
   evolving downstream, across the upper Mississippi and Ohio Valleys,
   Great Lakes and Ontario/Quebec by 12Z Saturday.  

   Perhaps most prominent within the evolving cyclonic mid-level
   regime, models indicate that a vigorous short wave trough emerging
   from the Arctic latitudes will dig across Manitoba and northwestern
   Ontario into the Upper Midwest/upper Great Lakes region.  This is
   expected to be accompanied by a significant reinforcing cold
   intrusion, in the wake of a deepening cyclone migrating across James
   Bay into Quebec.

   Farther south, seasonably cool and stable conditions are expected to
   generally prevail across the northern into southern tier of the
   U.S., in the wake of a prior cold front.  Seasonably high moisture
   content appears likely to be initially confined to one narrow plume
   across and east of the south Atlantic coast, and another across the
   Texas Gulf coast, beneath lingering subtropical ridging.  However,
   weak to modest southerly return flows are forecast to develop
   near/east of the south Atlantic coast, and across parts of the
   southern Plains into the Ozark Plateau/lower Mississippi Valley.

   North/northeast of the mid/upper Texas coastal plain, associated
   destabilization appears likely to remain rather weak, and based
   above a residual near surface stable layer.  Due to sizable spread
   among the various model output, it remains unclear whether this will
   become sufficient to support thunderstorm development.  If it does, 
   forcing to support activity may primarily coincide with the onset of
   mid-level height falls late Friday night across parts of
   central/northeast Texas into the Mississippi Delta vicinity.

   Otherwise, isolated to widely scattered thunderstorm activity also
   appears possible in association with modest boundary layer
   destabilization near mid/upper Texas coastal areas, and perhaps near
   northeast Florida coastal areas.  However, the risk for severe
   storms appears negligible.

   Tornado:  <2%     - None
   Wind:     <5%     - None
   Hail:     <5%     - None

   ..Kerr.. 10/18/2018



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Page last modified: October 18, 2018
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