SPC AC 051737

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1237 PM CDT Sun May 05 2024

   Valid 061200Z - 071200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS
   WEST-CENTRAL/CENTRAL OKLAHOMA AND SOUTH-CENTRAL KANSAS...

   ...SUMMARY...
   Numerous severe thunderstorms are expected to develop and move
   eastward Monday afternoon through Monday night across parts of the
   southern/central Plains. Multiple strong/potentially long-track
   tornadoes, very large to giant hail, and severe/damaging winds all
   appear likely.

   ...Synopsis...
   Upper cyclone apparent in Sunday morning satellite imagery over
   northern/central CA and the western Great Basin is expected to
   devolve into an open wave as it progresses eastward. This wave is
   forecast to continue eastward through the central Rockies and into
   the central Plains on Monday, becoming increasingly negatively
   tilted as it does. Strong mid-level flow will accompany this system,
   spreading eastward/northeastward into the central Plains early
   Monday and into the southern High Plains by Monday afternoon.
   Additional maturing into a closed mid-latitude cyclone is possible
   across the northern High Plains late Monday evening/early Tuesday
   morning. 

   Progression of this shortwave trough will contribute to significant
   mass response across the Plains, with strong low-level moisture
   advection resulting in mid 60s dewpoints to the OK/KS border by the
   early afternoon. Low 60s dewpoints will likely reach into eastern NE
   by the late afternoon. This increasing low-level moisture beneath
   steep mid-level lapse rates/cold mid-level temperatures will result
   in a moderate to strongly unstable airmass ahead of the approaching
   shortwave across much of OK, KS, and NE. Numerous severe
   thunderstorms are expected to develop as this wave interacts with
   this airmass, beginning during the late morning/early afternoon
   across SD/NE and then expanding southward across KS into OK
   throughout the remainder of the afternoon into the evening.
   Significant-severe weather is possible, including the potential for
   giant hail from 3" to 4" in diameter, gusts around 80 mph, and
   strong/potentially long-track tornadoes.

   ...Much of central/eastern NE and south-central/southeast SD into 
   western/northern/eastern KS and western MO...
   Strong height falls associated with this system will likely begin
   early Monday across NE and western/northern KS, interacting with the
   moderately moist and buoyant air mass expected to be in place. The
   cold front associated with this system will likely be moving through
   western NE and KS during this period as well. This initial
   development may not be overly strong, with the primary strengthening
   likely delayed until the afternoon over central NE and north-central
   KS where better low-level moisture and stronger buoyancy will be in
   place. Given the boundary-parallel orientation of the deep-layer
   shear vector and linear forcing along the front, relatively quick
   upscale growth into an organized convective line appears likely.
   This line would then track quickly eastward/southeastward through
   the evening and overnight.

   Large to very large hail around 2" to 2.5" in diameter is possible
   with the initial more cellular development. Primary threat will
   transition to severe gusts around 80 mph once the convective line
   organizes and consolidates, which appears likely during the
   afternoon. Additionally, despite the transition to a more linear
   mode, the tornado threat is expected to increase with eastern
   extent, supported by both an increase in low-level moisture/buoyancy
   and strengthening low-level kinematic fields. The greater damaging
   gust threat will likely extend into more far eastern KS and western
   MO, and the higher wind probabilities were expanded eastward to
   account for this potential. Some minor southeastward expansion of
   the 10% tornado probabilities was made as well.  

   ...Much of OK and adjacent portions of central/southern KS and far
   northwest/north-central TX...
   Height falls are expected to arrive later, and be more modest,
   across OK and adjacent central/south KS than areas farther north.
   Some capping appears likely through around 18Z as well. However,
   continued low-level moisture advection coupled with daytime heating
   is expected to result in air mass destabilization just as the height
   falls/large-scale ascent move into the region. This scenario appears
   to favor a discrete storm mode from south-central KS into southwest
   OK. Overall coverage may be limited, particularly until 00Z, but any
   storms that develop should quickly become supercellular and capable
   of all severe hazards, including giant hail from 3" to 4" in
   diameter, severe gusts to 80 mph, and strong tornadoes.
   Additionally, forecast hodographs are quite long, with little
   mid-level weakness. Mean storm motion is around 50 kt from 21 to
   00Z, with Bunkers right motion around 30 kt. This should be more
   than sufficient for storms to remain discrete and maintain supercell
   characteristics. This also contributes to a greater potential for
   long-track tornadoes. The tornado threat will persist pass sunset
   and into the evening, supported by the persistence of ample
   low-level moisture/buoyancy and a strengthening low-level jet. Most
   current guidance maximizes the STP at 8-10 around 03Z over
   south-central OK. 

   A threat for damaging winds and tornadoes should continue Monday
   night into early Tuesday with eastward extent into eastern OK and
   western AR given a sufficiently unstable and strongly sheared
   environment.

   ..Mosier.. 05/05/2024

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