Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed May 10 2023 17:31:12 ACUS02 KWNS 101731 SWODY2 SPC AC 101729 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Wed May 10 2023 Valid 111200Z - 121200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS CENTRAL OKLAHOMA INTO NORTHWEST KANSAS... ....SUMMARY... Strong/severe thunderstorms are forecast Thursday across the central and southern Plains, where large hail and a few tornadoes can be expected along with locally damaging winds. Isolated hail/damaging winds are also possible across the lower Mississippi Valley into the Southeastern states. ....Synopsis... A progressive upper-level low is noted translating eastward across the lower CO River Valley in mid-morning water-vapor imagery. Recent guidance has generally captured the progression and amplitude of this wave well over the past 12 hours or so, lending reasonably high confidence in its general evolution over the next 48 hours. This feature is expected to become slightly negatively tilted as it ejects into the southern/central High Plains during the 18-21 UTC period Thursday. The rapid deepening of a lee cyclone over the northern TX Panhandle into western KS will coincide with the eastward mixing of a dryline, which should be draped from southwest KS into western OK and northwest TX by mid-afternoon. The severe weather threat will be concentrated along and east/northeast of this boundary as thunderstorms develop by mid to late afternoon. Along the Gulf Coast, a weak mid-level perturbation, currently over central TX, will migrate east through the day, reaching the lower MS River Valley by peak heating. Thunderstorms developing in the vicinity of this feature will pose a risk for sporadic large hail and damaging winds. ....Central to Southern Plains... Recent surface observations across the southern/central Plains show a plume of rich (mid to upper 60s) dewpoints across much of TX into south-central KS. Poleward moisture advection will increase through Thursday afternoon as the surface low deepens over western KS and the Panhandles region, with widespread mid/upper 60s ahead of the sharpening dryline. Despite the high-quality moisture, mean meridional flow ahead of the low will relegate the steepest mid-level lapse rates (sampled by 12 UTC RAOBs over the High Plains) to western KS. This, in addition to early-morning clouds/showers, will mute the influence of low-level moisture to some degree, but MLCAPE values between 1000-2000 J/kg should be common across the warm sector by midday. 50 knot mid-level flow largely orthogonal to the dryline should overspread KS/OK through the day, resulting in favorable deep-layer shear orientations for discrete convection. Stronger synoptic and mesoscale lift across west/southwest KS will likely result in an arching band of convection, becoming more broken with southeast extent. A second round of storms is possible during the late afternoon/evening hours as a pocket of cold temperatures aloft associated with the upper low traverses western KS. Further south into OK, a combination of more peripheral synoptic lift and slightly stronger capping will limit convective coverage. T-storm development might be locally maximized across southwest to central OK where guidance has been consistently showing a secondary surface low/dryline bulge in latest guidance that may augment forcing for ascent along the dryline. Thunderstorm potential becomes even more conditional with southward extent along the dryline south of the Red River amid stronger capping and weaker ascent. Regardless of coverage, thunderstorms developing across southern KS into OK (and possibly northern TX) will likely take on supercellular characteristics given adequate buoyancy, deep-layer shear, strong effective-layer helicity, and favorable dryline/deep-layer shear vector orientations. All hazards will be possible with these storms, including the potential for very large (2 inch or larger) hail and a significant tornado. ....Lower MS Valley into the Southeast... Scattered thunderstorms will likely be ongoing at the start of the period across the lower MS valley in the vicinity of the mid-level perturbation. This activity will likely intensify through the day amid strong diurnal warming ahead of ongoing convection. Additional thunderstorms are expected along the western FL coast along a diurnally-driven sea breeze, as well as across parts of southwest GA. While buoyancy will be somewhat strong (around 2000-2500 J/kg MLCAPE), modest wind shear suggests intense convection may be somewhat short-lived. Consequently, sporadic large hail and damaging winds will be possible with strong updraft pulses through the day, and perhaps along any organized outflows associated with convective clusters. ...Moore/Leitman.. 05/10/2023 $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. 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