Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Apr 19 2023 05:54:00 ACUS01 KWNS 190553 SWODY1 SPC AC 190552 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1252 AM CDT Wed Apr 19 2023 Valid 191200Z - 201200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS WESTERN OKLAHOMA...CENTRAL/EASTERN KANSAS...SOUTHEAST NEBRASKA...NORTHWEST MISSOURI...AND PARTS OF IOWA... ....SUMMARY... Severe thunderstorms with the potential for very large hail, a risk for a few of tornadoes, and severe gusts will be possible late this afternoon into tonight across parts of the central states. ....Central/Southern Plains to the Upper Midwest Vicinity... A closed upper low is forecast to meander over eastern MT to southern SK today/tonight. An upper shortwave trough attendant to the low will pivot across the central/southern Rockies and into the Plains during the afternoon and into the overnight period. As this occurs, increasing southwesterly deep-layer flow will overspread the Plains, with a 55-70 kt 500 mb jet developing over KS/NE by 00-03z. An initial surface low is forecast near the southeast NE/northeast KS border this morning, before occluding by midday. However, as the mid/upper trough begins to eject over the Rockies and into the Plains, stronger cyclogenesis will result in a deepening low over western KS by late afternoon. This low will lift northeast during the evening, with a sharpening dryline extending southward across central KS into western OK/TX. Overnight, a cold front will sweep southeast across the central/southern Plains. A relative max in severe thunderstorm potential is expected in the vicinity of the triple point from central KS into southeast NE where the best combination of favorable shear, stronger forcing and adequate boundary-layer moisture will reside. Forecast guidance still indicates some degree of spread with regard to northward moisture return, but dewpoints to at least the low 60s F seem likely across central/eastern KS, northeast into the mid-MO Valley vicinity. Very steep mid-level lapse rates atop modest boundary-layer moisture will promote strong destabilization, and convective initiation appears likely near the triple point from north-central/northeast KS into southeast NE by 00z. Initial supercells capable of very large hail are possible. A few tornadoes also will be possible near the surface low and along the warm front where low-level vorticity and shear will be enhanced. As a low-level jet increases during the evening and the cold front surges southeastward across the central Plains, some upscale development into a line is possible with an accompanying increase in damaging wind potential. This activity should spread northeast into IA/southern MN and WI/northern IL overnight with a continued wind/hail threat. A more conditional threat is expected with southward extent along the dryline into parts of western/central OK, and perhaps as far south as western north TX. A sharp dryline will reside across western OK with surface dewpoints in the mid 60s possible. Large-scale ascent will be weaker with southward extent. However, strong heating along the dryline and favorable low-level convergence is likely to aid in attempts to overcome moderate capping. If capping is overcome, isolated discrete supercells will have a narrow window of opportunity to develop across parts of western/central OK. While mixing/entrainment of drier air is expected (and may delay convective initiation until near/after 00z), ECAPE still indicates MLCAPE near/above 2500 J/kg. Furthermore, enlarged low-level hodographs becoming elongated above 3 km are forecast. This parameter space will be more than sufficient to support potentially very large hail (3+ inch diameter). A tornado or two, along with damaging gusts also will be possible with any supercell that may develop. If cells can become established, severe potential will be limited in time/space given expected late initiation timing and increasing CINH with eastward extent after 00z. ....TX dryline... Model guidance currently indicates a paucity of convective potential along the dryline over parts of north-central TX southward to the Edwards Plateau. A conditionally very unstable boundary layer and deep-layer shear will support supercell potential. Any storm that manages to develop will likely pose a large-hail threat for at least an hour or two before this risk diminishes by mid evening. ...Leitman/Squitieri.. 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) .