SPC AC 020600

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0100 AM CDT Sun Apr 02 2017

   Valid 021200Z - 031200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR EAST
   TEXAS...CENTRAL AND NORTHERN LOUISIANA...AND FAR SOUTHWEST
   MISSISSIPPI...

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
   CENTRAL TEXAS AND MUCH OF EAST TEXAS EASTWARD INTO SOUTHERN ARKANSAS
   AND CENTRAL MISSISSIPPI...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL TEXAS
   INTO THE LOWER MISSISSIPPI VALLEY...

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

   ...SUMMARY...
   Numerous severe thunderstorms are forecast from parts of Texas
   eastward into the lower Mississippi Valley today and into tonight. 
   A concentrated area of significant wind damage is likely near and
   north of the I-20 corridor in east Texas and Louisiana.  The risk
   for tornadoes, a few of which may be strong/damaging, will probably
   maximize near and south of I-20 in Texas and Louisiana, along with
   the threat for hail.

   ...Synopsis...
   A closed mid-level low will evolve into an open wave and move from
   northern Mexico/Far West TX eastward to the ArkLaTex by early Monday
   morning.  A broad area of surface low pressure over the Rio Grande
   Valley will consolidate and develop northeast across central TX
   during the day and be near the OK/AR border at the end of the
   period.  A maritime warm front will advance northward across the
   northwest Gulf Coast region during the day as a cold front
   accelerates eastward across central TX during the afternoon and into
   LA during the overnight.  

   ...Central TX eastward into the lower MS Valley...
   A multi-hazard, likely multi-scenario forecast with intrinsic
   complexity/uncertainty is seemingly evident for today into tonight. 
   Late Saturday evening surface analysis and radar imagery show rich
   low-level moisture over the TX coast with a developing thunderstorm
   cluster in the middle Rio Grande Valley.  Strong to severe
   thunderstorms will likely be ongoing over central TX.  Severe
   gusts/wind damage appears to be the predominate threat with the
   early-day MCS.  As the surface low deepens, a concurrent strong
   low-level mass response will occur and the development of a 50-kt
   LLJ by mid morning is expected.  Strong low-level moist advection on
   the nose of the LLJ will be favorable for a continuation of early
   morning storms as the LLJ's terminus shifts eastward from
   east-central TX into the ArkLaTex by mid-late afternoon.  A
   concentrated zone of higher probability wind potential may be
   realized with a potential bowing system as increasing buoyancy
   (1000-3000 J/kg MUCAPE) and strong shear lead to an intense bowing
   MCS moving from TX into the ArkLaTex.  

   Coincident with the diurnal heating cycle, free warm sector
   thunderstorm initiation is likely from east TX into LA on the
   northern rim of the elevated mixed layer's stronger capping
   inversion (north of Interstate 10).  Persistent south-to-north
   oriented confluence zones in the warm sector will serve as the
   genesis areas with gradual thunderstorm/supercell development as
   stronger updrafts penetrate the LFC---beginning as early as the late
   morning and through the afternoon.  A moderate to very unstable
   boundary layer (MLCAPE ranging from 2000-3000 J/kg) is forecast from
   eastern parts of TX into LA.  Forecast soundings show large
   hodographs (200-400 m2/s2 0-1 km SRH) with strong effective shear of
   at least 50-kt.  It seems plausible several supercells may evolve
   from this activity and pose a threat for tornadoes and large to very
   large hail.  A couple of strong/damaging tornadoes are possible. 
   The latest model guidance suggests thunderstorm coverage will be
   less generally south of Interstate 10.  Nonetheless, models show
   isolated to widely scattered storms developing perhaps in
   conjunction with stronger deep forcing for ascent.  

   During the evening and overnight over the lower MS Valley, storms
   will likely spread into the region from the west.  Increasing
   moisture/buoyancy as the maritime front advances northward will
   favor an organized severe storm risk continuing into the region. 
   Thunderstorms within the strong flow fields will conditionally
   support the possibility for wind damage and tornadoes after dark.

   ..Smith/Gleason.. 04/02/2017

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