ENHANCED RISK OUT NOW
y 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0100 AM CDT Thu Mar 23 2023
   Valid 241200Z - 251200Z
   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS NORTHEAST
   LOUISIANA...SOUTHEAST ARKANSAS...AND WESTERN MISSISSIPPI...
   ...SUMMARY...
   Supercell thunderstorms capable of all severe hazards, including
   strong tornadoes, are possible across the Lower Mississippi Valley
   on Friday.
   ...Synopsis...
   Upper troughing is expected to be in place over the western CONUS
   early Friday morning. Strong mid-level flow will extend throughout
   the periphery of this trough into the more confluent flow north of
   the subtropical ridging across the eastern CONUS. A shortwave trough
   is forecast to move through this enhanced mid-level flow, tracking
   quickly eastward across the southern Plains during the day, and more
   northeastward into the Mid MS Valley overnight. Mid-level flow is
   expected to strengthen as the shortwave moves eastward, with 100+ kt
   at 500 mb spreading across TX into the Mid-South.
   At the surface, a low initially over north TX is forecast to move
   northeastward ahead of the approaching shortwave, moving into
   northern AR by Friday evening and through the Lower OH Valley
   overnight. This low is expected to deepen throughout the day, and
   this cyclogenesis will result in a broad area of moderate southerly
   flow across the Lower MS Valley/Mid-South into the Southeast and TN
   Valley. Environmental conditions appear favorable for numerous
   severe thunderstorms from the Lower MS Valley through the Mid-South
   and into the Mid MS and Lower OH Valleys.
   ...Lower MS Valley into the Southeast...
   A broad warm sector, characterized by dewpoints in the upper 60s, is
   forecast to be in place from east TX across much of the Lower MS
   Valley and Mid-South early Friday morning. Thunderstorms may be
   ongoing early Friday morning along a cold front moving eastward
   across east TX. This cold front is expected to make gradual eastward
   progress, as its parent surface low deepens while moving from
   eastern OK into AR. This overall evolution will contribute to a
   continued mass response across the warm sector, with low-level
   moisture increasing throughout the day amid strengthen southerly
   flow. This increase in low-level moisture coupled with modest
   heating is expected to result in airmass destabilization during the
   late afternoon. This destabilization coupled with large-scale ascent
   attendant to the approaching shortwave (perhaps augmented by
   low-level confluence) will likely result in discrete thunderstorm
   development within the warm sector ahead of the front. 
   Current thinking is that this initial development is most likely to
   occur in the TX/LA border vicinity. The downstream air mass will be
   moderately buoyant, with guidance suggesting MLCAPE around 1000-1500
   J/kg and max 2-6 km AGL lapse rates around 8 deg C per km. Robust
   vertical shear is also expected, with a strong low-level jet (i.e.
   50-60 kt at 850 mb) developing during the evening beneath
   strengthening mid-level flow. Forecast hodographs depict 
   substantial low-level speeds and veering, with 0-1 km storm-relative
   helicity from 200 to 300 m2/s2. A discrete supercell mode is
   anticipated initially, with all severe hazards possible, including
   strong tornadoes. With storms expected to develop in the LA/TX
   border vicinity, discrete storm maturation is anticipated across
   northeast LA, southeast AR, and western MS.
   Upscale growth into a convective line is anticipated after this
   initially discrete mode, with the line pushing eastward across MS
   and AL overnight. Robust kinematic fields are expected to persist,
   support a continued threat for strong gusts and line-embedded
   tornadoes.
   ...Mid-South into the TN and Lower OH Valleys...
   A more convoluted convective evolution is anticipated from
   central/northern AR northeastward into the Lower OH Valley on
   Friday. Storms will likely be ongoing along and north of stationary
   boundary extending from east-central OK northeastward into northern
   KY. A low-probability threat for hail is expected throughout the
   morning and into the early afternoon as warm-air advection promotes
   continued thunderstorm development along this boundary. 
   A gradual increase in storm intensity is then expected during the
   afternoon as the surface low begins to deepen across AR and
   large-scale forcing for ascent attendant to the shortwave increases.
   Buoyancy will be more modest than areas farther south, but the
   strong ascent and increasing shear is still expected to support
   intense updrafts. Given the presence of the stationary front and
   stronger forcing, a linear mode is anticipated, with this line then
   progressing quickly east-northeastward across the Mid-South during
   the evening and into more of the Lower OH and TN Valleys overnight.
   Strong wind gusts will be primary hazard within this line, but
   line-embedded tornadoes will be possible as well.
   ..Mosier.. 03/23/2023