Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Apr 19 2023 12:52:30 ACUS01 KWNS 191252 SWODY1 SPC AC 191250 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0750 AM CDT Wed Apr 19 2023 Valid 191300Z - 201200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO TONIGHT FROM NORTHEAST KS TO SOUTHWEST IA... ....SUMMARY... Scattered severe thunderstorms with very large hail (3 inch diameter or larger), a couple of tornadoes, and severe gusts are expected late this afternoon into early tonight from northeast Kansas into southwest Iowa. More isolated severe storms with very large hail may also occur farther south into western/central Oklahoma and northwest Texas this evening. ....Northeast KS to southwest IA this evening into tonight... Low-level moisture is more established in the warm sector compared to yesterday, with 60-65 F boundary-layer dewpoints from central TX to central KS this morning, and PW values above 1 inch. Moisture will continue to advect northward beneath a warm elevated mixed layer with very steep lapse rates of 8-9 C/km, in response to lee cyclogenesis across the central High Plains. The primary upstream shortwave trough will approach the central Plains tonight, supporting northeastward development of the lee cyclone toward IA, and a southeastward surge of a cold front across KS/OK. The more prominent zone for severe storm development this evening into tonight will be from northeast KS into southeast NE and vicinity. The warm elevated mixed layer and associated cap will inhibit warm sector thunderstorm development through much of the afternoon, but storm development is expected this evening across northeast KS and southeast NE. Here, low-level convergence and surface heating/mixing will be maximized to the northeast of the cold front/dryline triple point, along the northwest edge of the primary moisture/buoyancy axis. Storms that form in this area this evening will likely become supercells given MLCAPE in excess of 2500 J/kg, steep midlevel lapse rates, and sufficient deep-layer vertical shear. The storms will be sustained into the late evening and overnight hours as warm advection and mass flux increase into this zone with a strengthening low-level jet. The initial threat will be very large hail (potentially 3 inch diameter or larger), as well as damaging gusts. The increase in low-level shear/hodograph curvature during the evening, as the 60 F dewpoints surge into the frontal zone, suggests some potential for a couple of tornadoes, though storm mode will trend more linear overnight as convection develops southwestward as the cold front overtakes the dryline. ....Western/central OK into northwest TX this evening... Storm development is uncertain along the dryline this afternoon/evening, given little in the way of height falls/forcing for ascent, and the presence of a substantial cap. Storm initiation will rely on the depth of mixing with surface heating along the dryline, and on parcel residence time in the dryline zone of ascent. Flow in the 850-700 mb layer will be a bit more parallel to the dryline compared to yesterday, which may allow long enough residence times to reach an LFC. If storms form, the environment favors a conditional threat of isolated very large (3 inch plus) hail with any persistent supercells. This pattern of an evening low-level jet ramp up is also consistent with some increase in the late evening tornado threat, though low-level moisture is a bit marginal compared to past events. ...Thompson/Gleason.. 04/19/2023 $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .