Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Apr 14 2023 16:25:50 ACUS01 KWNS 141625 SWODY1 SPC AC 141624 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Fri Apr 14 2023 Valid 141630Z - 151200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST NEBRASKA INTO NORTHWEST OKLAHOMA... ....SUMMARY... Severe thunderstorms capable of producing large hail and damaging winds are most likely from late afternoon through evening from southeast Nebraska into central Kansas and northwest Oklahoma. Additional isolated severe thunderstorms are possible across south-central Texas through evening, and across parts of the Carolinas and southeast Virginia this afternoon. ....Central Plains Vicinity... At midday, a surface low was located near the central KS/NE border. A dryline extended south from the low across western KS into far west TX, while a cold front arced across southeast CO. The dryline is forecast to mix eastward to western OK and central TX by late afternoon, while the cold front sags south/southeast toward the OK/TX Panhandle and central KS. The northern extent of the cold front will shift east from southeast NE into central MN through evening. Ahead of these surface boundaries, modest moisture return is underway on strengthening southerly low-level flow. Upper 50s to near 60 F dewpoints are expected as far north as far southeast NE this evening. As the western upper trough begins to eject eastward this evening, large-scale ascent coupled with frontal convergence should provide support for thunderstorm development. Steep midlevel lapse rates (8-9 C/km) and modest boundary-layer moisture will support moderate to strong destabilization with MLCAPE values greater than 2000 J/kg forecast along/west of the I-35 corridor. While deep-layer south to southwesterly flow will remain modest through 500 mb (generally 25-35 kt), effective shear magnitudes around 30-35 kt will marginally favor initial high-based supercells. With time, upward development into clusters/bows is possible during the evening. Large hail (some greater than 2 inches) and damaging gusts (some to around 75 mph) are expected across the Slight risk (Level 2 of 5) area from southeast NE into northwest OK. Additional strong storms capable of gusty winds and hail will be possible in the post-frontal upslope regime across southeast CO into western KS just behind the southward-sagging cold front. High based convection with well-mixed sub-cloud profiles may support mostly dry downburst winds. Steep lapse rates and modest shear also could support large hail in any cells that can persist/remain organized. A more conditional threat may extent southward toward the I-40 corridor in western/west-central OK. Concerns over stronger capping with southward extent will preclude expansion of severe probabilities across OK. However, a strong/severe cell could develop near the dryline within the Marginal risk (Level 1 of 5) area as far south as I-40 in western OK. ....Edwards Plateau Vicinity in TX... Latest forecast guidance has been more aggressive in eroding midlevel capping across south/south-central TX this afternoon/evening. Deep boundary-layer moisture is forecast across south TX amid steep midlevel lapse rates, supporting strong destabilization this afternoon. Elongated forecast hodographs and supercell wind profiles suggest large hail (some potentially greater than 2 inches) will be possible if cells develop. Some potential exists for developing convection to form a bow tracking east toward the Middle TX Coast during the evening/early overnight period. If this occurs, some risk for locally damaging gusts also will exist. A Marginal risk (Level 1 of 5) has been included, and an upgrade to Slight risk (Level 2 of 5) may be needed in subsequent outlooks if trends continue to increase. ....Carolinas/southern VA this afternoon/evening... The closed midlevel low over the TN Valley will gradually evolve into an open wave while ejecting northeastward toward the Mid-Atlantic tonight. Surface dewpoints in the mid/upper 60s are in place across the Carolinas and will continue to spread northward toward southern VA. Surface heating amid cloud breaks is supporting weak destabilization early this afternoon. Midlevel lapse rates and vertical shear will remain modest (< 7 C/km and near 30 kt effective bulk shear), but MLCAPE approaching 1000 J/kg will support scattered storm cells/clusters. Isolated wind damage and marginally severe hail will be possible for a few hours this afternoon into early evening. ...Leitman/Thornton.. 04/14/2023 $$ = = = 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) .