SPC AC 101625

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1125 AM CDT Sun May 10 2020

   Valid 101630Z - 111200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS
   AFTERNOON/EVENING FOR PARTS OF THE OH VALLEY AND THE SOUTHERN HIGH
   PLAINS...

   ...SUMMARY...
   Isolated damaging winds and marginally severe hail are possible
   across a portion of the Ohio Valley and the southern High Plains
   this afternoon into this evening.

   ...IN/OH and vicinity this afternoon...
   A midlevel shortwave trough over IL this morning will move eastward
   to OH/WV/western PA by early tonight, along with an associated weak
   surface cyclone and cold front.  Though low-level moisture is
   limited, boundary-layer dewpoints in the low-mid 40s will combine
   with midlevel lapse rates of 7-8 C/km and daytime heating to boost
   SBCAPE to near 500 J/kg this afternoon ahead of the cold front. 
   Low-level flow will not be particularly strong (generally near 30
   kt), but there will be sufficient deep-layer shear for organized
   cell/line segments.  A broken band of storms is expected to develop
   by about 18z across IN and then spread eastward through the
   afternoon into northern KY and OH.  The stronger storms could
   produce isolated damaging gusts and small hail, prior to the
   weakening this evening across western PA and WV.

   ...Southern High Plains this afternoon/evening...
   Modest low-level moisture return (boundary-layer dewpoints in the
   low-mid 50s) is underway from the Rio Grande Valley into southwest
   TX this morning.  Some additional northward spread of the moisture
   is expected today near the TX/NM border, though advection will tend
   to be offset by vertical mixing this afternoon.  Inverted-v profiles
   beneath midlevel lapse rates in excess of 8 C/km will result in
   MLCAPE of 500-1000 J/kg, in an environment with effective bulk shear
   of 30-35 kt.  Widely scattered thunderstorms are expected by late
   afternoon from the higher terrain in southwest TX northward to a
   remnant baroclinic zone and upslope flow into the Raton Mesa, and
   the strongest storms could produce marginally severe hail and
   isolated strong outflow gusts.  Convection may persist as a small
   cluster or two into the early overnight hours near the TX/NM border,
   as low-level warm advection increases along the baroclinic zone. 

   ...FL Keys through tonight...
   Widespread rain and cloud debris persist across the Keys, south FL
   and the FL Straits, in advance of a diffuse midlevel trough crossing
   the Gulf of Mexico.  The more intense convection is well to the
   south of the Keys along the primary baroclinic zone from the
   southern Bahamas across western Cuba to the northwest Caribbean Sea.
   Substantial thermodynamic recovery as far north as the Keys appears
   unlikely, which will tend to limit the threat for strong-severe
   storms.

   ..Thompson.. 05/10/2020

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