SPC AC 170558

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1258 AM CDT Wed Apr 17 2024

   Valid 181200Z - 191200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
   MID MISSISSIPPI VALLEY AND LOWER OHIO VALLEY...AND OVER A PORTION OF
   NORTHERN TEXAS...

   ...SUMMARY...
   Scattered strong to severe storms capable of damaging winds, large
   hail, and perhaps a couple tornadoes will be possible Thursday from
   parts of eastern Missouri into the lower Ohio Valley and vicinity.
   Locally damaging winds and hail are also expected over parts of
   northern Texas.

   ...Synopsis...
   On Thursday, an upper low will move east from Manitoba into western
   Ontario, with a broad area of cyclonic flow aloft from the northern
   Plains to the Upper Great Lakes. South of the primary midlevel
   temperature gradient, moderate winds to around 50 kt will extend
   southward from MO into the OH Valley, with 30 kt midlevel winds into
   northern TX. Southwest winds of 30-40 kt will exist around 850 mb,
   aiding theta-e advection into the Mid MS/OH Valleys.

   At the surface, a cold front will exist roughly from northern MO
   into northwest TX Thursday morning, with a weak low moving from MO
   into the OH Valley ahead off the front. A warm front will lift
   northward ahead of the low, allowing moistening to occur over much
   of southern IL, IN, and northern KY during the day, and spreading
   into western OH overnight. Ample moisture ahead of this front will
   result in an elongated area of strong to severe potential throughout
   the day.

   ...Mid MS Valley into the lower OH Valley...
   Severe probabilities have been shifted farther west given latest
   model trends, as strong to severe storms could begin rather early in
   the day. Ongoing areas of storms are expected on the nose of the
   low-level jet, possibly in the form of an MCS, roughly over northern
   MO. As the warm front lifts north ahead of any such system, this
   could prove favorable for a swath of damaging winds. Otherwise,
   activity is expected to form near the low and along the cold front,
   where instability and shear will also favor supercells with large
   hail and perhaps tornado risk. Given the potential for early storms,
   this lends uncertainty to the forecast, and precludes an upgrade of
   higher coverage probabilities as placement would be uncertain.
   Regardless of early day evolution, moderate westerlies atop the
   expanding moist sector should favor areas of damaging wind, hail,
   and perhaps a few tornadoes during the day and through early
   evening. The severe risk could potentially reach into western OH and
   northern KY late, depending on upstream evolution.

   ...Northern TX...
   A cold front will push quickly south across OK and MO during the
   day, and across the Red River during the late afternoon and early
   evening. Given the late frontal arrival, strong destabilization will
   occur with full heating and upper 60s to lower 70s F dewpoints.
   MLCAPE over 3000 J/kg is forecast, with steep lapse rates through a
   deep layer.  Although shear will not be strong, hodographs will
   favor southeastward-moving cells developing near the front or within
   the narrow low-level lapse rate plume where it will become uncapped.
   Locally damaging downbursts along with hail will be possible with
   any storms that develop, warranting an upgrade in severe
   probabilities for this focused diurnal event.

   ..Jewell.. 04/17/2024

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