SPC AC 032000

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0300 PM CDT Thu Apr 03 2025

   Valid 032000Z - 041200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS
   AFTERNOON/EVENING FROM NORTHEAST TX TO MIDDLE TN...

   ...SUMMARY...
   Severe thunderstorms will continue to form and move along a stalled
   frontal zone from northeast Texas into middle Tennessee and southern
   Kentucky through late evening, with the possibility of very large
   hail and a couple of strong tornadoes.  Very large hail will be
   possible after midnight from southwest Texas into cnetral Texas and
   southern Oklahoma.

   ...Northeast TX to middle TN/southern KY this afternoon/evening...
   Severe storms are developing along and to the immediate cool side of
   a rain-reinforced baroclinic zone from northeast TX across AR and
   middle TN/southern KY.  Initial storm motions will tend to carry the
   convection to the cool side of the boundary (especially across AR),
   though there is some potential for surface-based supercells to form
   and move along the wind shift.  The warm sector to the south is
   characterized by boundary-layer dewpoints ranging from mid 60s F
   across TN/KY to low 70s F from northeast TX into southern AR.  The
   rich moisture and surface temperatures warming into the low-mid 80s
   beneath 7-8.5 C/km midlevel lapse rates maintain MLCAPE ranging from
   1500 J/kg east to 3000+ in northeast TX/northern LA.  Deep-layer
   vertical shear/hodograph length is more than sufficient for
   sustained supercells, while substantial low-level hodograph
   curvature (effective SRH of 200-300 m2/s2) and the moist boundary
   layer will support the potential for a couple of strong tornadoes
   with supercells moving along the boundary.  Otherwise, large hail of
   1.5-2.5 inches in diameter will be possible with both the
   surface-based and elevated supercells, as well as isolated wind
   damage as storms train along and just north of the boundary.

   ...SW into central TX and southern OK overnight...
   Within the large-scale trough over the Southwest, an embedded jet
   streak will move through the base of the trough from Baja to
   southwest TX by the end of the period.  Mass response to the
   approaching jet streak will result in strengthening warm advection
   and the likelihood of elevated thunderstorm development over
   southwest TX after 06z.  Storms will subsequently spread
   northeastward, with additional storm development expected by 12z
   from northwest TX into southern OK.  Steep midlevel lapse rates, a
   rapid increase in moisture above the surface, and strong deep-layer
   shear will favor elevated supercells capable of producing very large
   hail (2-3 inches in diameter), as well as isolated damaging surface
   winds.

   ..Thompson.. 04/03/2025

   .PREV DISCUSSION... /ISSUED 1130 AM CDT Thu Apr 03 2025/

   ...Southern Plains/Mid-South/Tennessee Valley...
   With a prominent upper trough over the West, strong southwesterly
   winds aloft will overlie areas along/north of a frontal zone
   extending from the middle part of Texas into the ArkLaTex/Mid-South,
   east-northeastward to the central Appalachians and Mid-Atlantic
   States. With neutral to slightly rising mid-level heights, the
   convectively reinforced front is forecast to move little today
   across the ArkLaTex, Mid-South, and Tennessee Valley.

   Even though large-scale ascent will tend to remain somewhat nebulous
   near the front and southward into the warm sector, persistent
   low-level warm advection should aid in renewed thunderstorm
   development along/near the stalled front through the afternoon and
   evening. Any convection which can form on or just south of this
   boundary will have a rather favorably moist low-level airmass, steep
   lapse rates aloft, and strong deep-layer shear to support organized
   updrafts.

   A notable diurnal strengthening of the low-level jet /45-55 kt/ is
   expected today across the ArkLaTex to the Mid-South/Lower
   Mississippi Valley, where it will impinge on the west/southwest to
   east/northeast-oriented effective front. This is concerning
   regarding supercell tornado potential later today, some of which
   could be strong (EF2+) given the magnitudes of the
   deep-layer/low-level shear and moisture-rich environment with
   surface dewpoints in the upper 60s/near 70F. That said, some
   modal/mesoscale uncertainties still persist as to warm-sector
   development and the coverage and longevity of surface-based
   supercells, with convection potentially tending to be more
   prevalent/likely just north of the effective front. Otherwise, large
   to very large hail will be a threat with the expected supercellular
   development along/north of the front, with upscale-growing clusters
   posing a damaging wind threat as well.

   ...West-central/North Texas and southern Oklahoma late tonight...
   Elevated supercells are expected to again develop late tonight
   (after midnight CDT) and early Friday as forcing for ascent
   increases to the north of the surface front. These storms will pose
   a large hail threat, and possibly some severe-wind potential as
   well, particularly if elevated bow echo development occurs as storms
   spread northeastward within a highly sheared environment.

   ...Central Appalachians to Mid-Atlantic/Delmarva...
   Remnants of convection and related outflow boundaries will serve as
   a northern limit to any appreciable severe threat today. While some
   details remain uncertain, any storms that develop along/south of the
   front could pose risks for hail and damaging winds.

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