SPC AC 091741

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1241 PM CDT Tue Jun 09 2020

   Valid 101200Z - 111200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF LOWER MICHIGAN AND INTO OHIO...

   ...SUMMARY...
   Scattered severe storms are possible from Ohio and Lower Michigan
   into parts of Pennsylvania, West Virginia, and New York Wednesday
   afternoon and evening. South of this area, a few strong to severe
   wind gusts will be possible.

   ...Synopsis...
   As remnants of Cristobal -- progged to be crossing Upper Michigan at
   the start of the period -- shift northward into Ontario, a
   negatively-tilting synoptic-scale trough is forecast to shift
   northeastward out of the central U.S. across the Midwest and Great
   Lakes regions.  This trough will be flanked by ridges on either
   side, one over the West and a second over the East that will be
   gradually shunted eastward into the western Atlantic through the end
   of the period.

   At the surface, remnants of Cristobal are progged to deepen as a
   synoptic low over southern Ontario with time, in response to the
   advance of upper troughing.  A trailing cold front is forecast to
   sweep eastward across the Midwest/Ohio and Tennessee Valleys/central
   Gulf Coast states through the day, and then should cross the
   Appalachians late in the period.

   ...Lower Michigan and Ohio Vicinity southward to the Gulf Coast...
   As the remnant low which was Cristobal shifts northward toward
   southern Ontario, a compact low/vort max -- within the larger-scale
   upper troughing -- is forecast to make an increasingly negatively
   tilted northeastward advance across the Midwest and into the Upper
   Great Lakes region through the first half of the period.

   As this system -- and associated cold front -- advance across Lake
   Michigan and Indiana into Lower Michigan and Ohio through the day,
   daytime heating/destabilization in conjunction with strong forcing
   for ascent will result in storm development through midday/early
   afternoon.  Strong -- but somewhat
   unidirectional/south-southwesterly flow with height is progged
   across the region, yielding shear that will favor
   fast-moving/rotating storms and/or small bowing segments, and
   attendant risk for strong/damaging winds.  Hail will also be
   possible, as will a couple of tornadoes across this area.  With
   time, an increasingly linear convective band is expected, as storms
   shift east to lakes Huron and Erie, and across Ohio into the evening
   hours, with an eventual wane in wind risk expected with time.

   Farther south, storms are forecast to develop during the afternoon
   along the cold front, as the airmass diurnally destabilizes.  Weaker
   shear expected across this region suggests lesser severe risk,
   though locally gusty/damaging winds and hail will be possible with
   stronger storms through the afternoon.

   ...NY/PA...
   Multiple rounds of storms are expected across the NY/PA region, as
   diurnal convection is expected to develop as very weak disturbances
   moving through the background short-wave ridging foster weak ascent
   across the area through the day.  Heating will support afternoon
   destabilization across the area, with 1000 to 2000 J/kg mixed-layer
   CAPE expected to evolve.  Isolated to scattered storms are expected
   to develop in response, though only modest shear expected suggests
   mainly multicell storms.  Locally damaging wind gusts will be
   possible with a few stronger storms, along with some hail risk.

   While this convection should wane by early evening, another round of
   likely-to-be-weakening convection should move west-to-east across
   western PA/western NY overnight, ahead of the advancing cold front. 
   While severe risk should diminish with time/eastern extent, a few
   stronger storms -- capable of producing gusty winds -- may linger as
   far east as central NY/central PA through the end of the period.

   ..Goss.. 06/09/2020

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