SPC AC 030555

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1255 AM CDT Fri May 03 2024

   Valid 031200Z - 041200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
   WESTERN AND CENTRAL TEXAS...AND THE SOUTHERN NEBRASKA/KANSAS
   VICINITY...

   ...SUMMARY...
   Scattered strong to severe storms will be possible Friday afternoon
   into early Saturday morning over parts of the central/southern Great
   Plains, and over the central Plains, beginning late afternoon/early
   evening.

   ...Synopsis...
   An upper low initially over the northern Plains/southern portions of
   the Canadian Prairie Provinces is forecast northeastward into/across
   western Ontario with time.  As this occurs, a short-wave trough will
   advance eastward across the northern Intermountain region through
   the day, and emerge into the northern and central Plains through the
   second half of the period.  Meanwhile, a much weaker disturbance is
   forecast to move eastward along the southwestern U.S./Mexico border
   and begin affecting the southern High Plains area by late afternoon
   before moving across the southern Plains overnight.

   At the surface, a developing cold front is forecast to shift
   southeastward into the central Plains through late afternoon, and
   then continue eastward/southeastward overnight.  Meanwhile, a
   dryline will mix gradually eastward across the southern High Plains
   through the afternoon.

   ...Portions of western Texas including the South Plains/Big
   Country/Concho Valley...
   As a very moist low-level airmass across western and central Texas
   warms through the day, substantial destabilization will occur. 
   Mixed-layer CAPE values will likely reach 3000 to 4000 J/kg east the
   dryline, which is expected to be mixing slowly eastward across the
   South Plains and eastern portions of the Permian Basin near peak
   heating.  By late afternoon, storm development is expected from the
   Panhandle south to/across the Rio Grande, with the most numerous
   storms expected within a zone extending from the South Plains to the
   Big Country, and south across the Concho Valley.

   While flow through the lower and middle troposphere will not be
   particularly strong, veering winds with height, and ample high-level
   flow, will support organized/rotating storms -- particularly given
   the very favorable thermodynamic environment.  Very large hail will
   likely occur with the strongest storms, along with locally damaging
   gusts.  A tornado or two may also occur, though overall risk should
   remain a bit tempered by somewhat modest low-level flow/shear.

   Into the evening hours, some congealing/upscale growth of convection
   is anticipated, which should gradually spread
   eastward/east-southeastward toward/into central Texas -- accompanied
   by risk for damaging winds and hail.

   ...Southern Nebraska southwestward across the western half of
   Kansas...
   Modest northward return of low-level moisture across Kansas is
   expected to commence ahead of the developing cold front through the
   afternoon.  Daytime heating of the moistening boundary layer will
   permit 1000 to 1500 J/kg CAPE to evolve, leading to the development
   of thunderstorms along the advancing front -- first across western
   Nebraska, and then shifting southeastward with time.  Isolated
   storms may also develop separately across eastern Colorado,
   eventually congealing into a larger convective cluster/system that
   is expected to move across Nebraska and Kansas through the evening.

   With shear sufficient for supercells, but a rather deep mixed layer
   anticipated, primary risk should be locally damaging wind gusts, as
   well as hail in the 1 to 1.75" range with the strongest storms. 
   With upscale growth expected however, risk should favor damaging
   wind gusts overall.  While storms will likely continue through the
   overnight period, shifting into/across the Mid-Missouri Valley
   region, severe threat should eventually diminish due to nocturnal
   boundary-layer stabilization.

   ..Goss/Wendt.. 05/03/2024

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