SPC AC 170556

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1256 AM CDT Wed Apr 17 2024

   Valid 171200Z - 181200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE OHIO VALLEY AND LOWER GREAT LAKES...AND IN PARTS OF NORTHEAST
   KANSAS AND WESTERN MISSOURI...

   ...SUMMARY...
   Scattered thunderstorms, capable of wind damage, isolated large hail
   and a tornado threat, are expected to develop across parts of the
   Ohio Valley and Lower Great Lakes this afternoon. Storms with large
   hail are expected tonight in parts of the central Plains and Ozarks.

   ...Ohio and Tennessee Valleys/Central Gulf Coast States...
   A negatively tilted upper-level trough, and an associated surface
   low, will move into the Great Lakes today. A corridor of maximized 
   surface dewpoints will move eastward across the Ohio Valley today,
   as a cold front approaches from the west. Scattered thunderstorms
   will likely develop during the late morning, as low-level
   convergence and instability increases. These storms, in the form of
   clusters or short line segments, will move eastward across the Ohio
   Valley and Lower Great Lakes region during the afternoon.

   RAP forecast soundings across far eastern Indiana and western Ohio
   during the early afternoon show a favorable environment for severe
   storms, with MLCAPE near 1500 J/kg and 0-6 km shear around 50 knots.
   This should support an isolated large hail threat with the more
   discrete rotating storms. A wind-damage threat will also be
   possible, especially with the more organized line segments. Forecast
   soundings suggest that low-level shear will become more favorable in
   the late afternoon, with 0-3 km storm-relative helicity increasing
   into the 225 to 250 m2/s2 range. For this reason, the tornado threat
   is expected to be greater a bit further east from central and
   eastern Ohio into far western Pennsylvania.

   Further south into the Tennessee Valley and central Gulf Coast
   states, isolated thunderstorms are expected to develop ahead of a
   cold front, and near a moist axis with surface dewpoints in the 60s
   F. MLCAPE in the 750 to 1000 J/kg range, along with 0-6 km shear
   from 40 to 50 knots will be sufficient for an isolated severe
   threat. Marginally severe wind gusts and hail will be the primary
   threats.

   ...Central Plains/Ozarks...
   An upper-level trough will move through the north-central U.S.
   tonight, as a 70 to 80 knot mid-level jet passes through the trough.
   In response, a 40 to 50 knot low-level jet will develop further
   south across the central Plains. Thunderstorms are expected to
   initiate near the northern edge of the low-level jet late this
   evening from central Kansas into far southeast Nebraska. These
   storms are expected to move eastward across northeast Kansas and
   into western Missouri. Forecast soundings in northeast Kansas around
   06Z have MUCAPE near 2500 J/kg, with effective shear around 45
   knots. This, combined with 700-500 mb lapse rates around 7.5 C/km,
   should be favorable for elevated rotating storms with potential for
   very large hail. The large hail threat is expected to be greatest in
   the 04Z to 07Z time window, but may persist through late in the
   period.

   ..Broyles/Lyons.. 04/17/2024

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