SPC AC 281937

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0237 PM CDT Mon May 28 2018

   Valid 282000Z - 291200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE CENTRAL HIGH PLAINS...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF THE
   CENTRAL AND SOUTHERN HIGH PLAINS AND ACROSS GEORGIA AND EASTERN
   ALABAMA...

   ...SUMMARY...
   Severe thunderstorms with very large hail, wind damage and a few
   tornadoes are expected across parts of the Great Plains.  A few
   tornadoes will also be possible over parts of Georgia and Alabama in
   conjunction with Alberto.

   ...Central High Plains Update...
   A cluster of severe storms currently exists across north central KS,
   with embedded supercells and large hail cores. Additional
   development is imminent southward along the dryline with further
   supercell development likely producing very large hail and perhaps a
   tornado. To the northwest, satellite imagery shows a distinct
   outflow boundary across northwest KS into northeast CO. Several
   hours of heating should eventually yield a favorable zone of
   supercell and/or tornado development as low-level shear will be
   enhanced. As a result, have expanded the 10% tornado probability
   line eastward into KS.

   For more information on the High Plains area, see mesoscale
   discussions 552, 553, 555, 557.

   ..Jewell.. 05/28/2018

   .PREV DISCUSSION... /ISSUED 1119 AM CDT Mon May 28 2018/

   ...Central Plains...
   A persistent upper low is centered over UT, with a mid-level jet
   wrapping around the low across AZ/NM into CO/NM.  Water vapor
   imagery shows a significant shortwave trough embedded in the
   stronger flow over northeast NM.  This feature will rotate into
   central CO later this afternoon, providing the lift for an active
   severe weather event across parts of the central Plains states.

   ...CO...
   Latest visible satellite imagery and surface analysis shows a
   boundary extending from southwest NE into eastern CO.  Low clouds on
   the north side of this boundary are slowing eroding, and should
   result in a corridor of moderate CAPE later today (dewpoints in the
   upper 50s and steep mid level lapse rates).  12z CAM solutions are
   consistent in the development of thunderstorms along/north of this
   boundary from just southeast of DEN into northeast CO.  Forecast
   soundings suggest a favorable combination of thermodynamics and deep
   layer shear of 50-60 knots, supporting supercells.  Enhanced
   low-level shear will also be favorable of a few tornadoes.  Have
   introduced a small 10% tornado risk area for this threat.  Very
   large hail and damaging winds will also be possible in this area.

   ...Western KS to TX Panhandle...
   Farther east, strong heating and ample CAPE will result in a line of
   thunderstorms roughly along the CO/KS border southward into the TX
   panhandle this afternoon.  These storms will rapidly become severe,
   capable of very large hail and damaging winds.  Isolated tornadoes
   are also possible in more persistent supercells.  These storms are
   expected to merge into a broken line, with an enhanced wind damage
   threat through the evening.

   ...GA/AL...
   The center of Alberto will track across the FL Panhandle and into AL
   today.  Considerable heating is occurring to the east of the center
   across parts of GA and southeast AL, where dewpoints are in the
   low/mid 70s.  CAM guidance suggests that scattered thunderstorms
   will form in this corridor later today, with forecast soundings
   indicating sufficient low level shear/helicity for some risk of
   tornadoes in the more persistent updrafts.  Have therefore upgraded
   this area to SLGT risk.

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