SPC AC 101952

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0252 PM CDT Wed May 10 2023

   Valid 102000Z - 111200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS NORTHEAST
   COLORADO INTO FAR SOUTHWEST NEBRASKA AND FAR NORTHWEST KANSAS...

   ...SUMMARY...
   Scattered severe thunderstorms capable of producing tornadoes, large
   to very large hail, and severe wind gusts remain likely this
   afternoon and evening along the High Plains. Additionally, more
   isolated strong to severe thunderstorms are possible tonight across
   east Texas and western Louisiana.

   ...Front Range/High Plains...
   The forecast remains on track based on recent observations and
   trends in hi-res guidance. 5% tornado probabilities were expanded
   slightly across northwest KS where a few cumulus clusters have shown
   notable vertical development within a recovering boundary layer
   (where easterly surface winds are enhancing low-level helicity). A
   significant wind area is introduced for portions of southeast CO
   into adjacent areas of NM, OK, and KS, where dewpoint depressions
   over 40 F are noted ahead of developing convection within the higher
   terrain. These trends suggest the environment is favorable for
   efficient downward momentum transfer within stronger downdrafts that
   may result in a couple of 75+ mph gusts. For additional near-term
   trends, see MCD #754.

   ...North Dakota...
   The Marginal area has been extended slightly westward across parts
   of north-central ND to better align with recent surface and
   satellite observations, which depict shallow cumulus development
   along a diffuse surface trough. A few recent runs of hi-res guidance
   suggest a storm or two may develop within this regime, and modified
   forecast sounding indicate that locations with
   temperatures/dewpoints in the mid 70s/upper 50s may feature
   sufficient buoyancy for effective bulk shear values approaching 30
   knots.

   ..Moore/Leitman.. 05/10/2023

   .PREV DISCUSSION... /ISSUED 1135 AM CDT Wed May 10 2023/

   ...Front Range/High Plains...
   An east/northeastward-moving upper trough over Arizona and preceding
   upper jet exit region will influence the High Plains with a
   meridional flow pattern into this afternoon and tonight. A lee
   cyclone will persist over eastern Colorado and the Raton Mesa
   vicinity with a warm front extending east across northwest Kansas to
   southeast Nebraska, with the southern High Plains dryline mixing
   east into a portion of west Texas. A plume of 50s F surface dew
   points will be maintained to the north of the aforementioned central
   High Plains front amid persistent easterlies in the lowest 1 km.

   As large-scale ascent preceding the upper trough overspreads the
   central to southern Rockies and adjacent High Plains, initial
   convection will develop over the higher terrain by early afternoon.
   This activity will spread north-northeastward and increase in
   coverage through early evening. Several supercells are likely along
   the Front Range from east-central WY to south-central CO with a
   primary threat of large hail. Potential will exist for a more
   intense/long-tracked supercell or two developing off the Palmer
   Divide towards the Denver metro area and South Platte Valley, where
   rather enlarged/elongated hodographs coupled with the steep
   mid-level lapse rate environment could support very large hail and
   tornadoes. A few slow-moving supercells should be sustained near the
   dryline/front intersection in the CO/KS/NE border area with a
   similar very large hail and tornado threat. 

   ...Southern High Plains...
   While isolated severe wind/hail potential is possible during the
   late afternoon near the Raton Mesa vicinity, the bulk of severe
   potential is likely to be delayed until late evening/overnight after
   the dryline retreats west. This will yield increasing moisture timed
   with a strengthening low-level jet and greater mid-level DCVA ahead
   of the Arizona/New Mexico shortwave trough. With a more westerly
   component to mid-level flow, especially with southern extent,
   potential will exist for a few supercells capable of large hail and
   severe wind gusts across the Texas South Plains/Permian Basin.

   ...Southeast Texas/Louisiana...
   An MCV over east-central Texas should drift towards the ArkLaTex
   today. Regenerative, slow-moving deep convection is ongoing along
   the upper Texas Gulf Coast, with recent scattered development
   underway to the Louisiana coastal plain. A belt of enhanced
   low-level winds is consistently progged to spread from just off the
   Texas coast to the Sabine Valley by afternoon. This would yield
   enlargement to the low-level hodograph in an otherwise weak
   deep-layer shear regime. However, given the degree of ongoing
   convection, diurnal destabilization is expected to be muted.
   Therefore, some diurnal potential for transient low-level
   circulations is anticipated but its still unclear whether a more
   favorable brief tornado and isolated damaging wind corridor can
   develop. It is possible that the primary severe risk, but still on a
   relatively isolated basis, occurs late tonight as storms potentially
   redevelop across far eastern Texas into Louisiana. 

   ...Far northern Minnesota/North Dakota...
   A low-amplitude shortwave impulse will move east atop the northern
   extent of the upper ridge near the international border through the
   afternoon/evening. With the northeast plume of steep mid-level lapse
   rates impinging on the area, MLCAPE of 500-1500 J/kg should be
   common from central North Dakota into northwest Minnesota. While the
   bulk of supercell development should be confined to southern
   Manitoba, multicell clustering may spread/develop across the
   international border this evening with a threat for isolated
   damaging wind and severe hail.

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