SPC AC 081730

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1230 PM CDT Fri Jun 08 2018

   Valid 091200Z - 101200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   MT...

   ...SUMMARY...
   Severe thunderstorms are expected on Saturday across the northern
   Rockies, while pockets of other strong to severe thunderstorms are
   possible from a portion of the central and northern Plains through
   the Ohio Valley and Middle Atlantic states.

   ...Northern Rockies/Northern High Plains...

   Strong mid-level height falls are forecast to spread across the
   northern inter-mountain region into western MT during the latter
   half of the period. Associated cold front will surge across western
   MT to a position near CTB-BTM by 10/00z. This boundary is expected
   to serve as a focus for robust thunderstorm development as strong
   large-scale forcing should easily induce deep convection within a
   strongly sheared and steep lapse rate environment. Initial
   thunderstorm development may be somewhat high based, and possibly
   supercellular in nature. However, subsequent movement toward central
   MT should allow for lowering cloud bases and upscale convective
   growth as boundary layer will be more moist/buoyant across this
   region. While large hail should accompany this activity, it appears
   damaging wind threat will increase with late-night squall line.


   ...Central Plains to Middle Atlantic...

   Generally weak large-scale steering currents will prevail across the
   Midwest into the Middle Atlantic region Saturday. As a result,
   predictability will necessarily be low regarding possible
   thunderstorm clusters that could generate locally severe
   hail/damaging winds. Even so, there is some confidence that a late
   day1 MCS, or strong thunderstorm clusters, could migrate into the
   Mid-MO Valley region by daybreak Saturday. Remnants of this
   convective activity should influence potential thunderstorm
   development downstream later in the day. Latest guidance suggests 
   the most likely corridor for robust thunderstorm development will be
   across portions of the Mid-MS Valley immediately ahead of early-day
   thunderstorm complex. Hail/wind may be noted with renewed convection
   from IA into IL.

   Other isolated robust thunderstorms may be noted along a corridor
   from southern OH into VA where strong surface heating is expected to
   induce buoyancy sufficient for deep convection. Despite weak
   deep-layer shear there is reason to believe gusty winds and perhaps
   some hail could occur given the seasonally steep lapse rates.

   ...MAXIMUM RISK BY HAZARD...
   Tornado:   2%     - Marginal
   Wind:     15%     - Slight
   Hail:     15%     - Slight

   ..Darrow.. 06/08/2018

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