SPC AC 121727

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1227 PM CDT Fri Apr 12 2019

   Valid 131200Z - 141200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR NORTHERN
   LOUISIANA...SOUTHERN ARKANSAS...AND SMALL PORTIONS OF WESTERN
   MISSISSIPPI AND EAST TEXAS...

   ...SUMMARY...
   Numerous severe thunderstorms capable primarily of damaging winds
   and tornadoes, are expected across portions of east Texas,
   Louisiana, southern Arkansas, Mississippi and surrounding areas
   Saturday and Saturday night.

   ...Synopsis...
   A vigorous mid-level trough initially over the Southern Rockies will
   pivot eastward through the southern Great Plains and into the
   western part of the Ozark Plateau by Sunday morning.  A surface low
   over the TX Hill Country will develop northeastward and deepen and
   reach the vicinity of the confluence of the Ohio and Mississippi
   Rivers.  Trailing from this low, a cold front will sweep across east
   Texas to near the Sabine River by sunset, and then continue eastward
   across the lower Mississippi River into Mississippi and eventually
   western Alabama.  

   ...East-central TX eastward into western AL...
   Southerly low-level flow will transport an increasingly moisture
   rich airmass northward into the Arklatex and lower MS Valley during
   the day.  It is likely showers and thunderstorms, some potentially
   capable of severe gusts and large hail, will be ongoing across
   central TX into northeast TX prior to midday.  Surface heating
   within the destabilizing warm sector will lead to moderate buoyancy
   (MLCAPE 1000-2000 J/kg) over the Sabine Valley and LA by early to
   mid afternoon.  Strong flow veering/increasing with height from
   southeasterly to south-southwesterly, and reaching 60 to 70 kt at
   mid levels, will support well-organized rotating updrafts with the
   stronger storms.  Convection will continue spreading eastward
   through the evening and into the overnight hours.  

   Some lingering questions about the tornado risk remain due in part
   to some conditional factors yet to occur.  However, it appears the
   tornado risk may maximize in 2 corridors.  First, a diurnally
   focused tornado risk (primarily supercellular) across northern LA
   into far southern AR vicinity between 3-9pm.  A second area of
   potential concern may focus from northeast LA near the MS River
   east-northeast across central and into parts of northeast/east MS
   during the evening into the overnight.  A mix mode of supercell/QLCS
   or hybridization of the two within a convective line are possible. 
   Along with damaging gusts, strong tornadoes may also occur with a
   few of the most intense storms.  While the pre-frontal, cellular
   convection should diminish overnight, a semi-organized band of
   storms -- with embedded rotating updrafts and continued
   severe/tornado potential -- will move across the central Gulf Coast
   states through the end of the period.

   ...North Carolina/southeast Virginia and vicinity...
   Models forecast that the eastern fringe of a warm front associated
   with the developing south-central U.S. storm system will lie across
   the Carolinas/Virginia vicinity during the day.  With some heating
   of a moist low-level airmass yielding around 1000 J/kg mixed-layer
   CAPE during the afternoon, scattered/diurnally driven thunderstorms
   are expected.  While not excessive, shear -- aided by 35 kt
   mid-level west-southwesterlies -- will be sufficient for storm
   organization, and thus risk that a couple of storms reach severe
   levels.  Hail and gusty/locally damaging winds would be the primary
   severe risk, before storms weaken into the evening hours.

   ...MAXIMUM RISK BY HAZARD...
   Tornado:  15% SIG - Moderate
   Wind:     45%     - Enhanced
   Hail:     15%     - Slight

   ..Smith.. 04/12/2019

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