SPC AC 271730

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1230 PM CDT Mon May 27 2019

   Valid 281200Z - 291200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM A PORTION
   OF THE SOUTHERN AND CENTRAL PLAINS TO THE UPPER MIDWEST AS WELL AS
   FROM OHIO INTO PENNSYLVANIA...

   ...SUMMARY...
   Severe storms (capable of large hail, damaging wind and tornadoes)
   are possible Tuesday from the central and southern Plains eastward
   to the Midwest.  Severe storms with large hail, damaging wind and a
   couple of tornadoes are also possible from the Ohio Valley into a
   portion of the Northeast States Tuesday afternoon and early evening.

   ...Synopsis...

   A low-amplitude shortwave trough will move off the northeast coast
   Tuesday morning, while upstream a more significant upper trough will
   move into the central Plains before continuing northeast into the
   upper MS Valley region Tuesday night. By 12Z Tuesday the surface
   pattern should be characterized by a warm front from eastern PA
   northwest to a surface low over the Great Lakes. A cold or
   stationary front will trail southwestward from this low to another
   area of low pressure over the central Plains. A dryline/Pacific
   front will extend southward from the central Plains low through
   western KS and western TX.

   ...Southern and central Plains through the upper Midwest...

   Rich low-level moisture with upper 60s to around 70F dewpoints will
   reside in the warm sector beneath 7-8 C/km mid-level lapse rates
   associated with the eastward expansion of the elevated mixed layer.
   Some areas of stratus may reside across a portion of this region,
   but should mix out by late morning to early afternoon, with diabatic
   warming further contributing to destabilization with MLCAPE from
   2000-3000 J/kg likely. Warm air at the base of the EML will likely
   result in at least a modest cap in much of the warm sector. By mid
   afternoon, forcing attending a mid-level jet moving northeast
   through the base of the upper trough should result in storm
   initiation along the Pacific front from south central NE through
   central KS and possibly as far south as western OK. Some CAMs also
   indicate a separate area of storm development along  a portion of
   the warm conveyor belt from eastern KS into MO and southern IA. 
   Wind profiles with 40-50 kt effective bulk shear will support
   supercells as the initial storm mode, but some storms will
   eventually evolve into linear MCSs. While low-level hodographs are
   forecast to remain modest most of the day, 0-1 km helicity should
   increase by early evening as the low-level jet strengthens. Large
   hail and damaging wind will be the main threats, but a window for
   tornadoes will exist especially from late afternoon through early
   evening. Overnight, most storms will have evolved into lines or
   clusters, but will continue to pose a severe threat as they continue
   east through the upper Midwest, mainly within zone of ascent along
   and just north of the stationary front. 

   ...Ohio Valley into a portion of the northeast States...

   An area of rain and thunderstorms developing within zone of
   isentropic ascent on the cool side of a warm front and in
   association with a low-amplitude shortwave trough, will move through
   a portion of the Northeast States early in the day. In wake of this
   activity surface dewpoints in the upper 60s will advect eastward
   through the warm sector contributing to moderate instability
   (1500-2000 J/kg MLCAPE) as the boundary layer warms during the
   afternoon. Forecast soundings indicate at least a weak inversion
   associated with the eastern extension of the elevated mixed layer.
   However, storms will likely initiate along the stationary front as
   well as lake breezes and spread southeast through the warm sector.
   This region will remain within zone of moderate westerlies with
   35-45 kt effective bulk shear supportive of organized storms
   including supercells and bowing line segments. Damaging wind and
   large hail will be the main threats with this activity, but a couple
   of tornadoes will also be possible through early evening.

   ...MAXIMUM RISK BY HAZARD...
   Tornado:  10%     - Enhanced
   Wind:     30%     - Enhanced
   Hail:     30% SIG - Enhanced

   ..Dial.. 05/27/2019

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