SPC AC 052302

   Day 1 Convective Outlook AMEND 1
   NWS Storm Prediction Center Norman OK
   0602 PM CDT Sun May 05 2019

   Valid 052300Z - 061200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM WEST TEXAS
   INTO SOUTHEAST NEBRASKA...INCLUDING MUCH OF KANSAS AND WESTERN
   OKLAHOMA...

   AMENDED TO ADD MORE OF OK AND KS IN SLIGHT RISK

   ...SUMMARY...
   Widely scattered severe storms capable of large hail and damaging
   winds are most probable from west Texas into eastern Nebraska, and
   possibly expanding across much of western Oklahoma this evening.

   ...Amendment Update...
   Expanded Slight Risk for significant hail and damaging winds
   eastward across more of Kansas, western Oklahoma, and northwest
   Texas. 

   ...20Z Outlook Update...
   Severe probabilities were reduced in portions of Virginia, North
   Carolina, and Florida to the west of deeper convection in those
   areas.  Storms (especially in Florida) continue to shift eastward
   toward open Atlantic waters and are leaving relatively stable
   conditions in their wake.

   Farther west, severe probabilities across northwestern/north-central
   Kansas (near Russell and Hill City) were increased.  Latest CAMs
   indicate mature convection traversing these areas, and very steep
   mid-level lapse rates will support a risk of hail with stronger
   cores.  Latest satellite and lightning imagery suggests early-stage
   development upstream of these areas (northwestern Kansas) and these
   trends may continue through the afternoon.  Ref MCD 541 for
   short-term convective trends in western Kansas.

   ..Jewell.. 05/05/2019

   .PREV DISCUSSION... /ISSUED 1150 AM CDT Sun May 05 2019/

   ...Southern/central High Plains...
   Isolated/widely scattered supercells capable of large hail and
   eventually damaging winds, and possibly some tornado risk, are
   expected across a broad north-south expanse of central/southern High
   Plains. These storms are expected to develop near the dryline late
   this afternoon and east-southeastward into a moistening boundary
   layer. Moist advection east of the dryline, combined with diurnal
   heating and very steep mid-level lapse rates, should contribute to
   preconvective MLCAPE in the 2000-3000 J/kg range, amidst 40-50 kt
   effective-shear. Significant/2-inch+ hail may occur from the most
   intense cores. As the low-level jet increases early this evening and
   LCLs lower, some tornado risk may exist, particularly across the
   Caprock vicinity of northwest Texas.

   ...NE/IA and vicinity...
   Widely scattered to scattered thunderstorms are expected along/ahead
   of the southeastward-spreading surface cold front this afternoon
   into early evening, offering damaging to severe gusts and sporadic
   large hail. Surface heating, near a moist axis characterized by 50s
   F surface dew points, should remove MLCINH and boost buoyancy to
   values favorable for strong-severe convection. Forecast soundings
   suggest peak preconvective MLCAPE ranging from 1500-2000 J/kg over
   southern NE to around 1000-1500 J/kg in central IA, with the
   corridor of supportive MLCAPE becoming weaker/narrower from there
   into WI. Low-level winds are forecast to remain weak, but clusters
   or bands of convection may organize and shift southeastward away
   from the frontal zone with time.

   ...NC/southern VA...
   Widely scattered to scattered thunderstorms are expected this
   afternoon, with damaging gusts and sporadic hail possible. The
   tornado threat appears more marginal/conditional, given the lack of
   enlarged low-level hodographs amidst nearly unidirectional wind
   profiles; however storm-scale/boundary interactions and slightly
   backed surface flow just ahead of the low may support one from a
   supercell taking advantage of favorable boundary interactions.

   Aided by a shortwave trough and right-entrance region of a
   cyclonically curved jet segment, sufficient strength/duration of
   surface heating should occur to virtually eliminate MLCINH,
   fostering steep boundary-layer lapse rates and around 1000-1500 J/kg
   MLCAPE. 40-50 kt effective-shear magnitudes should be common,
   supporting some supercell potential.

   ...Florida to coastal Mid-Atlantic States...
   See Mesoscale Discussion 538 for short-term details regarding the
   severe risk across northern Florida, with locally damaging winds the
   main severe risk. South of the ongoing midday squall line/bowing
   complex across northern Florida, additional severe storms are
   expected across the central Peninsula.

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z