SPC AC 311945

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0245 PM CDT Fri May 31 2019

   Valid 312000Z - 011200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER EASTERN
   NORTH CAROLINA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER SOUTHWEST
   TEXAS INTO EASTERN NEW MEXICO...

   ...SUMMARY...
   Severe storms will persist across North Carolina and southern
   Virginia producing damaging winds and hail into the evening. Severe
   storms are also expected across Far West Texas and southeast New
   Mexico late this afternoon into the evening.

   ...Discussion...

   Previous forecast remains generally on track with only minor
   adjustments needed. Severe storms ongoing across NC into VA will
   persist into the evening. Other severe storms including a few
   supercells should develop this afternoon across west TX. See SWOMCD
   911 for more details. Strong storms with more sparse coverage are
   also expected from a portion of the northern and central Plains into
   the Great Lakes region.

   ..Dial.. 05/31/2019

   .PREV DISCUSSION... /ISSUED 1127 AM CDT Fri May 31 2019/

   ...South-central Appalachians to Carolinas/southern Virginia...
   A shortwave trough over KY/TN will track east into southern VA and
   NC tonight. A cyclonically curved belt of moderately strong
   westerlies (35-50 kt at 500 mb) will persist downstream across the
   Carolinas and southern Appalachians. Boundary-layer heating is
   underway ahead of the trough, beneath 6.5 to 7 C/km mid-level lapse
   rates. The most robust buoyancy/strongest instability should develop
   across the eastern NC vicinity by peak heating where surface
   temperatures warming into the low to mid 90s overlap mid 60s dew
   points.

   A cluster of convection is ongoing near the OH/KY/WV border area and
   thunderstorms will become increasingly numerous downstream to the
   southeast across the Appalachians. Additional scattered
   thunderstorms should evolve east across the Piedmont and along the
   sea breeze, most probable across NC. While low-level winds should
   remain modest, speed shear between the low to upper-levels should
   foster several cells with mid-level rotation with an attendant
   severe hail and damaging wind threat. The greatest likelihood for
   clustering appears to be across central to eastern NC where the
   environment would support an enhanced risk for strong to isolated
   severe wind gusts.

   ..Texas to eastern NM...
   An isolated damaging wind and marginally severe hail risk should
   exist downstream of an ongoing short line segment in east-central
   TX. 2000-2500 J/kg of MLCAPE will be common ahead of this segment,
   with potential for additional development towards the Upper TX
   Coastal Plain this afternoon. Modest deep-layer shear should limit
   the potential for greater organization. 

   Farther west, weak mid/upper height rises will occur late today into
   tonight. Nevertheless, ample low-level moisture characterized by low
   to mid 60s surface dew points currently across the Pecos
   Valley/Permian Basin will foster scattered storm development over
   the higher terrain of southeast NM and the TX Trans-Pecos by late
   afternoon. A veering wind profile with height in conjunction with
   favorable speed shear from 500-250 mb should support a large hail
   risk along with isolated sig. Consolidation of convection into a
   small MCS tonight appears possible in parts of west TX. Increasingly
   weak 700-500 mb flow amid the height rises should limit organization
   potential and marginalize the risk for severe wind gusts.

   ...Upper Midwest/Upper Great Lakes...
   Guidance appears to be overly aggressive (especially the NAM) with
   the degree of evapotranspiration ahead of the southward-moving cold
   front. 12Z observed soundings from Green Bay, Minneapolis,
   International Falls, and Aberdeen sampled mean-mixing ratios only
   around 7 g/kg. Given the predominant westerly low-level flow ahead
   of front, model forecasts up to 13 g/kg by early evening appear
   woefully too high.

   Cloud-free diabatic heating will yield very warm surface
   temperatures coincident with very steep mid-level lapse rates.
   Boundary-layer dew points should mix into the lower to mid 50s and
   yield a plume of modest buoyancy at peak heating. Scattered
   thunderstorm development is most likely across SD into far northern
   NE in association with a minor mid-level impulse shifting east from
   the Black Hills. More isolated thunderstorm coverage is anticipated
   immediately along the front from central MN into northern Lower MI.
   The eastern portion of the front should overlap the periphery of
   moderate mid-level westerlies and could support a few cells with
   mid-level updraft rotation capable of isolated severe wind and hail
   during the late afternoon and evening.

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