SPC AC 111958

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0258 PM CDT Thu Apr 11 2024

   Valid 112000Z - 121200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM WESTERN
   WEST VIRGINIA INTO SOUTHEAST OHIO AND VICINITY...

   ...SUMMARY...
   Severe thunderstorms with a few tornadoes, scattered damaging winds,
   and isolated severe hail are possible across the upper Ohio River
   Valley and parts of the Appalachians this afternoon into tonight.
   Scattered damaging winds and a couple of tornadoes remain possible
   this afternoon across the northern and central Florida Peninsula.

   ...20Z Update...
   Gradual clearing and warming is taking place ahead of the cold front
   and deepening surface low, with destabilization spreading north
   toward the OH River. Cells developing over eastern KY into WV may
   increase in intensity over the next few hours, and move
   north/northeast toward OH and western PA eventually. Low-level shear
   remains favorable for a weak tornado risk with the strongest cells
   along with a few damaging gusts.

   See mesoscale discussion 422 for more information.

   Farther south, a few storms remain over central FL, with isolated
   severe storms still possible. For more information see mesoscale
   discussion 423.

   ..Jewell.. 04/11/2024

   .PREV DISCUSSION... /ISSUED 1136 AM CDT Thu Apr 11 2024/

   ...Upper Ohio River Valley...
   Some forecast uncertainty persists in the short term regarding the
   magnitude of today's severe risk, largely attributable to persistent
   cloud cover, scattered warm sector showers/thunderstorms, with a
   broken overcast still prevailing at midday, even with a
   northeastward-expanding dry slot per water vapor imagery. While
   there are thermodynamic uncertainties and potential limitations,
   will continue to defer to favorable aspects of strengthening 1-2 km
   southerly winds and the steady deepening phase of the surface
   cyclone across the Ohio Valley. It generally appears that the
   currently depicted risks areas still largely reflect the relatively
   highest probability corridor for severe storms across the upper Ohio
   River Valley and Allegheny Plateau vicinity.

   Weak instability coupled with some enlargement of the hodograph can
   regionally support an environment in which discrete cells and
   semi-discrete clusters evolve into supercells. A few tornadoes are
   possible if stronger updrafts/supercells manage to develop, in
   addition to an accompanying threat for damaging gusts and perhaps
   isolated marginally severe hail.

   ...Mid-Atlantic States and Carolinas...
   A less focused and less certain severe risk appears to exist across
   the region. Cloud cover remains prevalent at midday coincident with
   low-level upslope flow, although some clearing is noted early this
   afternoon across the southern Appalachians vicinity. Where modest
   destabilization does occur this afternoon, long hodographs would
   conditionally support storm organization with any robust updrafts.
   Isolated to widely scattered strong to severe storms capable of a
   threat for damaging gusts and a couple of tornadoes are possible,
   particularly near the mountains/Blue Ridge, with a lower
   probability/lesser anticipated storm coverage expected farther east
   over the coastal plain/Delmarva.

   ...Florida...
   A broken band of thunderstorms will continue to move inland this
   afternoon across the western and northern Florida Peninsula. Ahead
   of this convection, warming boundary temperatures with dewpoints
   around 70F, beneath a likely lingering of capping aloft and weak
   mid-level lapse rates (12z observed sounding from Tampa Bay), is
   supporting MLCAPE of 750-1250 J/kg. Strong/veering wind profiles
   will support severe storms including some embedded supercells and
   locally intense clusters capable of tornado/damaging wind risks
   through at least mid-afternoon, with storm intensity/organization
   expected to gradually diminish into late afternoon and early
   evening.

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