SPC AC 221225

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0725 AM CDT Fri Apr 22 2022

   Valid 221300Z - 231200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS WESTERN
   NEBRASKA TO THE TEXAS PANHANDLE...

   ...SUMMARY...
   Episodic significant severe weather is possible across portions of
   the central to southern High Plains beginning late this afternoon
   and continuing into tonight. Very large hail and damaging
   straight-line winds, in addition to at least a few tornadoes are
   anticipated.

   ...Southern to central High Plains...
   As robust cyclogenesis occurs from the Denver metro area to the NE
   Panhandle this afternoon into early evening, mid-level height falls
   will overspread an arcing dryline from central NE to the TX South
   Plains. Initially high-based convective development is most likely
   across the western Panhandles into western KS. With a plume of mid
   50s to low 60s surface dew points expected to be maintained ahead of
   the dryline, this convection should deepen into scattered discrete
   supercells. Large hail, some of which may be significant, should be
   the primary initial hazard. Despite strong gradient surface winds,
   strengthening of the low-level jet will yield increasingly enlarged
   clockwise-curved hodographs during the early evening. This would
   typically favor tornadoes as well, however, guidance differs
   substantially with the degree of vertical boundary-layer mixing east
   of the dryline. As such, confidence is low for a greater tornado
   threat and HREF-based guidance indicates a rather pronounced
   convective wind signal despite the primary discrete mode. Guidance
   is more consistent in depicting cold low-level theta-e advection
   from the south during the evening. This should result in a general
   weakening convective trend towards late evening.

   A later round of separate convective development is likely towards
   late evening as the Pacific cold front impinges on the western
   extent of the buoyancy plume near the NE/CO/KS border area. This
   should result in a north/south-oriented convective line quickly
   spreading into western portions of NE/KS. Very strong wind profiles
   should promote a threat for severe wind and some hail, although
   duration and spatial extent overnight will probably be limited by
   the pervasive cold low-level theta-e advection in the warm sector,
   reducing available CAPE with time. 

   ...Western SD and northwest NE...
   A rather tight baroclinic zone will lie to the north of the
   slow-moving warm front/quasi-stationary frontal zone extending from
   the deepening central High Plains cyclone. A narrow bent-back plume
   of 50s surface dew points should be maintained beneath an initially
   stout elevated mixed layer. Guidance differs with where exactly this
   corridor will setup, but it is plausible that a surface-based storm
   may ride along the boundary within an SRH-enriched environment near
   the SD/NE border area. Additional storms, likely elevated, are
   possible farther west-northwest. Hodographs will be highly
   elongated, yielding the potential for a longer-lived supercell or
   two, with the main threat being significant large hail.

   ...Upper Midwest...
   Isolated, marginally severe hail will be possible mainly this
   morning, and separately farther north tonight, within a low-level
   warm theta-e advection regime. This potential will be supported by
   steepening mid-level lapse rates attendant to an expanding Great
   Plains elevated mixed-layer and adequate shear within the
   cloud-bearing layer.

   ..Grams/Jewell.. 04/22/2022

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z