Storm Prediction Center Day 1 Outlook (For Friday)

 

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