Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Aug 10 2023 19:47:23 ACUS01 KWNS 101947 SWODY1 SPC AC 101945 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0245 PM CDT Thu Aug 10 2023 Valid 102000Z - 111200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MID MISSOURI VALLEY AND VICINITY... ....SUMMARY... Isolated severe thunderstorms remain possible over parts of the eastern and central states this afternoon into tonight, including eastern North Carolina/southeast Virginia and parts of the Upper Midwest vicinity. ....Discussion... The main outlook adjustment being implemented in this update, aside from minor/local tweaks of the areal outlines, is an expansion of MRGL risk across the Iowa vicinity. Expectations are that an at least loosely organized MCS will move across the Iowa vicinity overnight, and that local/low-end severe potential may accompany the strongest cells. Otherwise, no appreciable changes appear necessary at this time. ...Goss.. 08/10/2023 ..PREV DISCUSSION... /ISSUED 1139 AM CDT Thu Aug 10 2023/ ....Eastern Carolinas/southeast Virginia... A convectively augmented shortwave trough over the southern/central Appalachians will continue eastward today. A cluster of thunderstorms, likely MCV aided, is ongoing across coastal areas of the Carolinas at late morning. Although considerable cloud cover immediately preceding the cluster may be a thermodynamic hindrance, more appreciable destabilization is expected in more immediate coastal areas. Where storms intensify, a seasonally strong/cyclonically curved belt of westerlies (50+ kt at 500 mb) would support organized storms including the possibility of a few supercells and well-organized/moderately fast-moving clusters capable of wind damage and some tornado risk. Although uncertain, there is a scenario is which a secondary round of regional convective development occurs late this afternoon near the southeastward-moving weak front and/or preceding surface trough. While deep-layer shear will tend to weaken late this afternoon/early evening, wind profiles should conditionally remain supportive of well-organized storms, potentially including a few supercells. This could yield some storms capable of damaging winds, hail, and possibly a tornado, prior to the risk abating/shifting offshore by mid-evening. ....Dakotas/Upper Midwest and eastern Nebraska... As a mid/upper ridge shifts east, a low-amplitude trough will overspread the northern Great Plains. This will help induce a weak surface cyclone over western North Dakota with a surface trough arcing south into central Nebraska and a warm front extending southeast through southern Minnesota. Relatively modest boundary-layer moisture and deep-layer shear will be limiting factors to a more prolific severe threat across the region. But steeper mid-level lapse rates within an elevated mixed layer will spread east across most of South Dakota and much of Nebraska by early evening and support a confined corridor of moderate buoyancy with MLCAPE of 1000-2000 J/kg. Effective bulk shear of 25-35 kts should support a mixed mode of a few supercells and multicell clusters. The most likely zone for scattered thunderstorm development in the late afternoon should be near the surface trough/warm front intersection in the northeast South Dakota border area with ND/MN. Increasingly isolated development should trail south along the trough. A mix of large hail and severe wind gusts will be the main threats, with some potential that an MCS evolves and continues southeastward this evening. ....Mid-South/Tennessee Valley... Modifying outflow from early day thunderstorms should serve as a focus for redevelopment later this afternoon, along the remnant front to the north. Additionally, another round of low-level warm theta-e advection-driven storms should occur after sunset tonight. A modest combination of mid-level lapse rates and vertical shear should support a mainly isolated severe threat, with sporadic instances of damaging gusts and marginal hail possible. ....Coastal Mid-Atlantic/southern New England... Low-level warm theta-e advection will strengthen today and translate northeast from the Mid-Atlantic across New England this afternoon and evening. Low-topped convection (perhaps void of lighting flashes in some cases) should develop amid meager surface-based instability as thermodynamic profiles become saturated. Aside from localized wind damage, the potential for a brief tornado also exists owing to enlarged low-level hodograph curvature. ....Central High Plains... Isolated high-based thunderstorms should develop off the higher terrain of southeast Wyoming and far north-central Colorado near a lee surface trough. A deep mixed boundary layer along the adjacent High Plains could support a few severe wind gusts during the late afternoon to early evening. ....West-central/northwest Texas... Hot surface temperatures along the dryline may support isolated thunderstorm development late this afternoon and early evening. Should deep convection become sustained, the very deeply mixed boundary layer could yield a few severe-caliber wind gusts. $$ = = = 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) .