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   Day 2 Convective Outlook   
   NWS Storm Prediction Center Norman OK   
   1133 AM CST Sat Dec 27 2025   
      
   Valid 281200Z - 291200Z   
      
   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SUNDAY AFTERNOON   
   AND EVENING ACROSS PARTS OF EAST CENTRAL AND SOUTHEAST   
   MISSOURI...ADJACENT NORTHEASTERN ARKANSAS AND NORTHWESTERN   
   TENNESSEE...CENTRAL AND SOUTHERN ILLINOIS...INDIANA...WESTERN OHIO   
   AND ADJACENT SOUTHERN LOWER MICHIGAN...WESTERN AND NORTHERN   
   KENTUCKY...   
      
   ...SUMMARY...   
   Strong thunderstorms may develop across parts of the middle   
   Mississippi Valley Sunday afternoon, accompanied by at least some   
   risk for severe weather while spreading into lower Ohio Valley   
   through Sunday evening.  This may include potential for a tornado or   
   two across parts of central Illinois into north central Indiana.   
   Otherwise, potentially damaging wind gusts appears the primary   
   severe threat.   
      
   ...Discussion...   
   Much of the interior U.S. remains anomalously warm, as westerlies   
   across the Pacific into western North America undergo amplification.   
    Later today through Sunday, models indicate that this will include   
   mid/upper ridging building inland across British Columbia and the   
   Pacific Northwest, through the Canadian/northern U.S. Rockies and   
   adjacent Prairies/northern Great Plains.  Downstream, it appears   
   that a pair of short wave troughs will come in phase while migrating   
   across and east of the Rockies, and provide support for strong   
   cyclogenesis.  By late Sunday night, guidance generally indicates   
   that the center of a deep, occluding surface low will reach the Lake   
   Huron/Georgian Bay vicinity, with a strong trailing cold front   
   advancing through the western slopes of the Appalachians and   
   northwestern Gulf/Gulf coast region.   
      
   ...Middle Mississippi/Ohio Valley...   
   There remains notable spread within/among the various model output   
   concerning the evolution of the developing surface cyclone across   
   the lower Missouri Valleys through Great Lakes region, including   
   timing of periods of more rapid deepening Sunday through Sunday   
   night.  This could substantially impact the location, timing and   
   extent of any associated thunderstorm development and accompanying   
   severe weather potential.   
      
   In general, it does appear that the pre-frontal warm sector will be   
   relatively moist, with surface dew points near/above 60F likely as   
   far north as a developing warm front, east of the deepening surface   
   low, across parts of middle Mississippi Valley into southern Great   
   Lakes region, by Sunday afternoon.  Convection allowing guidance and   
   other model output suggests that forcing for ascent along the warm   
   front, near and east of the low, may be the focus for highest   
   thunderstorm probabilities through the period.  However, based on   
   forecast soundings, relatively warm mid-level temperatures will tend   
   to minimize CAPE, and the risk for severe hail and wind for   
   convection rooted above the cool/stable boundary layer appears   
   negligible.   
      
   Relatively warm air aloft appears likely to be problematic within   
   the surface warm sector as well, particularly given forecast weaker   
   mid/upper forcing for ascent.  However, there does appear a   
   consensus in model output that a corridor of weak pre-frontal   
   boundary-layer destabilization could develop by early Sunday   
   afternoon across parts of south central/east central Missouri into   
   central Illinois.  Coincident with strengthening deep-layer wind   
   fields/shear and perhaps a period of glancing mid/upper support for   
   upward vertical motion, there may be a window of opportunity for   
   strong thunderstorm development, which could spread just ahead of   
   the front into the Ohio Valley before diminishing Sunday evening.   
      
   Based on forecast soundings, low-level hodographs to the   
   east-southeast of the deepening cyclone may become conducive to   
   low-topped supercells posing the risk for a tornado or two across   
   parts of central Illinois into north central Indiana late Sunday   
   afternoon.  Otherwise, low-level hodographs, trending more linear   
   along the front to the southwest, will generally support a narrow   
   line of convection with potential mix down 40-50 kt mean flow in the   
   lowest 3 to 6 km.   
      
   Once thunderstorm development wanes, the potential for convectively   
   enhanced gusts will diminish, but strong wind gusts associated with   
   the cold frontal passage are likely through much of the remainder of   
   the Ohio and Mississippi Valleys.   
      
   ..Kerr.. 12/27/2025   
      
   $$   
      
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