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Jan 19, 2017 0830 UTC Day 3 Severe Thunderstorm Outlook
Updated: Thu Jan 19 08:11:59 UTC 2017 (Print Version | 20170119 0830Z Day 3 shapefile | 20170119 0830Z Day 3 KML)
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 Forecast Discussion
   SPC AC 190811

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0211 AM CST Thu Jan 19 2017

   Valid 211200Z - 221200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM LOUISIANA AND
   MISSISSIPPI EASTWARD TO GEORGIA...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   SLIGHT RISK AREA...

   ...SUMMARY...
   A few episodes of severe storms will be possible from Saturday
   morning through Sunday morning across a broad area of the lower
   Mississippi Valley and the Southeast States.

   ...Lower Mississippi Valley to the northeast Gulf coast...
   A strong mid-upper trough, now south of the Aleutians, will reach
   the CA coast and northwest Mexico by day 2 (Friday), and continue
   eastward across the southern Plains to the lower MS Valley by
   Saturday night/Sunday morning (end of day 3).  There are some
   disagreements among the operational models, with the NAM appearing
   to reflect some convective feedback and eastward development of the
   synoptic cyclone too fast compared to the GFS/ECMWF.  Without the
   feedback, low-level mass response/flow should remain relatively weak
   during the day Saturday across LA/MS in the main part of the warm
   sector.  The primary synoptic cyclone and associated large-scale
   forcing for ascent will approach the MS River by the end of the
   period.

   Complicating factors this period will be any lingering influence of
   ongoing convection Saturday morning from MS into AL, and a somewhat
   nebulous focus for additional storms during the afternoon across
   LA/MS (well ahead of the synoptic wave/cold front).  Any storms that
   form here will do so in an environment with steep midlevel lapse
   rates, moderate buoyancy, and sufficient deep-layer shear for
   supercells capable of producing large hail (potentially some very
   large) and damaging winds.  The stronger low-level wind profiles are
   expected farther east and overnight in association with a lead speed
   max progressing inland from the Gulf.  Enhancement to low-level
   shear/SRH from south/southeast AL into the FL Panhandle and
   southwest GA will favor supercells with damaging winds and
   potentially some tornado risk, depending on the details on the
   low-level shear and near-ground lapse rates inland.

   Will opt to maintain a rather broad 15%/slight risk area in this
   update, though portions of the outlook area may need to be
   considered for higher coverage/intensity probabilities once
   uncertainties are reduced.

   ..Thompson.. 01/19/2017

   CLICK TO GET WUUS03 PTSDY3 PRODUCT

   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0830Z

        
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Page last modified: January 19, 2017
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