ZCZC SPCSWOMCD ALL ACUS11 KWNS 311558 SPC MCD 311558 ILZ000-IAZ000-MOZ000-KSZ000-311830- Mesoscale Discussion 0315 NWS Storm Prediction Center Norman OK 1058 AM CDT Sun Mar 31 2024 Areas affected...northern Missouri and adjacent portions of southern Iowa/northwestern Illinois Concerning...Severe potential...Watch unlikely Valid 311558Z - 311830Z Probability of Watch Issuance...5 percent SUMMARY...An initial period of increasing thunderstorm development appears likely across parts of northern Missouri into southeastern Iowa and and northwestern Illinois his afternoon. This may include strong thunderstorms posing a risk of severe hail for an hour or two early this afternoon across parts of northwestern Missouri, before a broader area of generally weaker thunderstorms evolves while spreading northeastward. DISCUSSION...Deepening convective development is evident within a narrow corridor, roughly west-northwest of the St. Joseph through Chillicothe MO vicinity. This is rooted above a near-surface inversion layer, along/above a strengthening frontal zone, aided by ascent supported by weak to modest low-level warm advection. Beneath anticyclonic flow within the crest of broad mid/upper ridging east of the southern Rockies into the Appalachians, mid/upper support for convection, if any, appears subtle. However, latest model output indicates increasing probabilities for thunderstorm initiation west-northwest through north of the Chillicothe vicinity by 17-18Z, where/when forecast soundings indicate modest conditional and convective instability in the presence of strong convective layer shear. This environment may be conducive to the evolution of an initial supercell structure of two, which may pose a risk for severe hail. Thereafter, guidance suggests warmer and more strongly capping elevated mixed-layer air will tend to gradually spread across and north of the surface warm frontal zone. As this occurs, the warm advection driven convection, while perhaps becoming more widespread, may tend to become increasingly displaced to the north of the better instability near and south of the frontal zonal, resulting in diminishing risk for severe hail. ..Kerr/Thompson.. 03/31/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LSX...DVN...DMX...EAX...OAX... LAT...LON 39909505 40619549 40839287 40629147 40239104 39749232 39739339 39909505 NNNN