SPC AC 271650

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1150 AM CDT Mon Apr 27 2026

   Valid 271630Z - 281200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS
   EAST/SOUTHEAST MISSOURI...SOUTHERN ILLINOIS...WESTERN KENTUCKY...AND
   NORTHWEST TENNESSEE...

   ...SUMMARY...
   Numerous severe thunderstorms are expected from the mid
   Mississippi/lower Ohio Valleys into the Mid-South through this
   evening, with a threat for multiple strong to intense tornadoes
   (EF3+), widespread severe/damaging wind gusts, and scattered large
   to very large hail.

   ...Mid Mississippi Valley/Midwest into the Mid-South/Lower
   Mississippi Valley...
   Forecast scenario largely unchanged in that a very active
   severe-weather/tornado day is expected regionally, especially into
   late afternoon and this evening. Initially, a relatively long-lived
   linear cluster of convection persists at late morning across
   east-central/south-central Illinois, with additional initially
   elevated storms on its eastern/southern periphery, moving from
   eastern Illinois into Indiana, with severe hail and damaging winds
   persisting as early day hazards.

   Over time, air mass will continue to moisten and rapidly destabilize
   along/south of the MCS-associated outflow from central Missouri into
   south-central Illinois. A mid/upper-level trough will eject
   northeastward from the northern/central Plains into the Midwest and
   middle Mississippi Valley through the period. Low-level mass
   response will encourage the primary surface low to consolidate
   across Minnesota/Wisconsin by this evening, with a warm front
   effectively delineated by the morning convection.

   Strengthening west-southwesterly flow aloft associated with a 50-70
   kt mid-level jet will overspread much of the warm sector by peak
   heating, and a 35-45 kt south-southwesterly low-level jet will both
   provide ample low-level and deep-layer shear to support supercells.
   Initially discrete surface-based development appears likely to occur
   into mid-afternoon across the mid Mississippi Valley/Mid-South ahead
   of the surface cold front, and perhaps along weak low-level
   confluence zones in the open warm sector including generally near
   the confluence of the Mississippi/Ohio Rivers southward into the
   Mid-South.

   These supercells will exist in a very favorable environment for
   tornadoes through the afternoon and evening, and multiple strong to
   intense tornadoes (EF2/3+) appear likely, especially from parts of
   Missouri into Illinois along/near the effective front. This strong
   tornado potential will also likely extend farther south within the
   warm sector into the Mid-South.

   By early evening, convection will probably tend to consolidate into
   clusters of supercells and then more linear segments with some
   increase in damaging wind potential aside from large hail and a
   continued multi-mode tornado risk tonight.

   ...ArkLaTex into Texas...
   While storm coverage may trend lesser with southwest extent, the
   potential for at least isolated intense storms will exist across the
   region. Supercells capable of producing large to very large hail and
   occasional damaging winds are expected. Increasing low-level
   warm/moist advection tonight could foster additional robust
   thunderstorms along the retreating dryline and eventually the
   southward-moving cold front.

   ..Guyer/Weinman.. 04/27/2026

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