SPC AC 140538

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1238 AM CDT Fri Mar 14 2025

   Valid 141200Z - 151200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS THE
   MID-MISSISSIPPI VALLEY AND PORTIONS OF THE LOWER OHIO VALLEY...

   ...SUMMARY...
   A regional outbreak of severe storms is likely across the
   Mid-Mississippi Valley to the Lower-Mississippi Valley, including
   portions of the Lower Ohio Valley. Tornadoes, several of which could
   be strong, widespread damaging winds with gusts from 70 to 90 mph,
   and scattered large hail up to baseball size will be possible.

   ...Discussion...

   Satellite imagery depicts a well-defined upper trough over the
   southwestern U.S./northwest Mexico. This feature is forecast to
   advance into the southern Rockies by sunrise as a 115kt 500mb speed
   max translates across southern NM. This jet max should increase to
   near 125kt as it translates into southwest OK by 18z, then weaken to
   near 100kt overnight over northern IL. Water-vapor/radar data
   suggest the leading edge of large-scale forcing is currently
   spreading across western NM. Latest model guidance suggests intense
   12hr mid-level height falls (on the order of 240-270m) will spread
   across the southern Plains into IA as left-exit region of the
   aforementioned jet shifts into the mid-MS Valley. At the surface, a
   pronounced dry line will surge across the central Plains, arcing
   from a very deep surface low over northwest KS-eastern OK by 18z.

   Strong boundary-layer heating is forecast ahead of the cyclone, and
   convective temperatures will easily be breached as temperatures warm
   into the lower 70s. While surface dew points will remain a bit low,
   SBCAPE should exceed 1000 J/kg and robust convection will readily
   develop along the wind shift. Of particular concern will be the
   efficiency of mixing very strong flow downward within this
   convection. Forecast soundings exhibit 50kt just off the surface,
   and very steep lapse rates will prove favorable for severe gusts
   with any convection today. Widespread wind damage, with speeds
   likely exceeding 70 mph are expected. Severe squall line should
   organize and surge northeast across the mid-MS Valley during the
   afternoon/evening hours.

   Farther southeast, LLJ is forecast to strengthen markedly across
   eastern AR/MO into IL. This will allow somewhat higher
   boundary-layer moisture to advance across the lower into the middle
   MS Valley prior to thunderstorm development. Latest thinking is
   supercells should develop ahead of the fast-moving 500mb speed max,
   with some propensity for activity lingering across the mid-South as
   the right-entrance region of the jet influences longevity of
   convection. Forecast soundings strongly favor organized convection
   with supercells expected. Higher moisture content into eastern
   MO/southwest IL will contribute to higher tornado probabilities with
   these strongly sheared supercells. Longer-lived updrafts may produce
   strong tornadoes, in addition to very strong winds and large hail.

   Southern extent of the regional outbreak will likely be influenced
   by the lack of stronger forcing across the lower MS Valley. Even so,
   isolated severe supercells are expected within the less-forced
   environment. This activity may linger well into the overnight hours.

   ..Darrow/Moore.. 03/14/2025

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