SPC AC 091643

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1143 AM CDT Tue May 09 2023

   Valid 091630Z - 101200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS
   CENTRAL/EASTERN KANSAS...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTH
   CAROLINA AND SOUTHEAST VIRGINIA...

   ...SUMMARY...
   A corridor of severe thunderstorms is expected today across parts of
   Kansas, with embedded swaths capable of producing very large hail,
   damaging severe gusts, and a few brief tornadoes. Scattered damaging
   winds and isolated severe hail are also possible this afternoon into
   early evening across eastern North Carolina and southeast Virginia.

   ...Kansas/southern Nebraska...
   A severe MCS continues to mature/expand and show early signs of
   modest southeastward acceleration as of late morning/1130AM CDT
   across north-central Kansas. As a surface cold pool expands,
   persistent warm/moist advection will help to maintain this MCS
   southeastward parallel to the instability/thickness gradient, with
   additional southward expansion likely across central Kansas early
   this afternoon as the boundary layer warms/destabilizes. The
   potential for widespread/locally intense wind gusts will likely
   increase as the MCS reaches east-central Kansas including the I-135
   and near/south of I-70 corridors and Kansas Turnpike vicinity. Large
   hail will be possible, especially with semi-discrete storms on the
   southwest flank of the MCS (or completely distinct from it). A brief
   tornado risk may also exist with line-embedded circulations.

   Additional strong/severe development cannot be ruled out later this
   afternoon in vicinity of trailing outflow across northwest Kansas
   and/or atop the surface cold pool across northern Kansas/far
   southwest Nebraska. Storms may also develop around late afternoon
   trailing westward to the dryline in southwest Kansas. Should this
   occur, a broader MCS may form and push south-southeast into the
   Ozark Plateau to northern Oklahoma this evening. But an increasingly
   disorganized trend is anticipated tonight as mid-level flow weakens
   substantially with southern extent owing to the presence of an
   anticyclone over southern Oklahoma.

   ...Southeast Virginia and eastern Carolinas...
   No changes in outlook reasoning/assessment for this region. A
   shortwave trough will move southeast from the Lower Great Lakes
   across the Mid-Atlantic States today. A belt of enhanced westerly
   flow will accompany this feature, and provide support for sufficient
   deep-layer shear to foster thunderstorm organization. Although
   surface winds will be veered mostly to the west-northwest, there
   will still be adequate low-level moisture in place for weak to
   moderate buoyancy to develop given abundant insolation.

   Most guidance shows isolated to scattered thunderstorms developing
   this afternoon with a mix of multicells and a few supercells. A
   threat for both severe hail and damaging winds should be greatest
   across southeast Virginia and northeast North Carolina, with more of
   an isolated damaging wind threat southward into South Carolina. 

   ...Texas/Louisiana...
   Strong/locally severe thunderstorms are possible this afternoon,
   influenced by development/intensification on the periphery of
   multiple MCVs via two de-intensified MCSs. Scattered to numerous
   thunderstorms will likely increase downstream of these features,
   later this morning into the afternoon. Despite the weak shear, low
   to mid 70s surface dew points suggest a threat for wet microbursts
   and isolated severe hail will be possible. 

   A conditionally favorable supercell threat may redevelop in a
   portion of Deep South Texas later this afternoon. A belt of enhanced
   mid-level westerlies to the south of the minor mid-level lows will
   yield adequate bulk shear for supercells along residual convective
   outflow. Primary uncertainty is the degree of low-level moisture
   recovery in the wake of morning convective outflows (mean mixing
   ratio below 12 g/kg in the 12Z BRO sounding).

   ...Northeast Colorado to western North Dakota...
   Isolated to scattered late-afternoon thunderstorm development is
   possible along a surface trough from the Nebraska Panhandle to
   western North Dakota vicinity. While MLCAPE will likely remain weak
   (at or below 1000 J/kg), 500-mb southwesterlies around 30-35 kt will
   support a threat for isolated severe hail and locally strong gusts
   into the early evening. Overnight, a cluster of elevated
   thunderstorms should develop in the northeast Colorado to
   Wyoming/Nebraska border area as weak mid-level height falls
   overspread weak low-level upslope flow. Isolated large hail will be
   the main threat.

   ...Central/eastern Montana...
   Long hodographs/forcing for ascent enhanced by an approaching
   mid-level trough, in conjunction with a modestly moist/unstable
   environment, may allow for some stronger or locally severe storms
   capable of hail and/or wind from mid-afternoon through early
   evening.

   ..Guyer/Bentley.. 05/09/2023

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