Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Aug 04 2023 20:00:20 ACUS01 KWNS 042000 SWODY1 SPC AC 041958 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Fri Aug 04 2023 Valid 042000Z - 051200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WITHIN THE NORTHEAST...NORTHERN/CENTRAL MISSOURI...PORTIONS OF THE CENTRAL PLAINS... ....SUMMARY... Scattered severe thunderstorms remain possible across parts of the Northeast, Missouri, and the central into the southern High Plains later today through early tonight. ....20Z Update... Minor changes were made to the wind probabilities within the Mid-South/Southeast to account for observations and stabilization behind ongoing convection. The remainder of the outlook is unchanged. ...Wendt.. 08/04/2023 ..PREV DISCUSSION... /ISSUED 1134 AM CDT Fri Aug 04 2023/ ....Synopsis... A broad mid-level trough continues to slowly progress across the Northeast as an upper ridge remains in place across the southern CONUS, with multiple mid-level perturbations cresting the upper ridge over the Central Plains. Though some cloud cover and showers/thunderstorms persist across the Northeast, adequate clearing through the remainder of the morning should efficiently heat the boundary layer beneath cooler mid-level temperatures and stronger flow aloft to promote strong to potentially severe thunderstorms through the afternoon. Meanwhile, residual clouds, showers, and thunderstorms should clear across the MO Valley into the Southeast today, with surface heating contributing to adequate buoyancy to support strong to potentially severe thunderstorms. These storms should initiate with the passage of the aforementioned mid-level impulses cresting the upper ridge. Lastly, upslope low-level flow will support the development of strong to potentially severe thunderstorms across the central into the southern High Plains later this afternoon and evening. ....Northeast... Scattered to potentially widespread thunderstorms are expected to initiate across the Hudson Valley late this morning into early afternoon ahead of a surface lee trough as surface heating continues across the Northeast. 16Z mesoanalysis shows modest (i.e. 6-6.5 C/km) mid-level lapse rates overspreading the Hudson Valley. Nonetheless, -14 to -15 C 500 mb temperatures and 70+ kts of 300 mb flow (in association with an approaching upper-level jet streak) will promote adequate instability (given mid 60s F surface dewpoints) and deep-layer shear to support a severe threat this afternoon. Multicells and transient supercell structures are expected, with large hail and damaging gusts the main concerns. By late afternoon, storms should congeal into one or more clusters. If this occurs, then damaging gusts will become the primary threat. ....MO Valley into the Southeast... Ongoing clouds and precipitation should gradually clear through the afternoon to support increasing buoyancy (perhaps over 3000 J/kg MLCAPE) as 7+ C/km mid-level lapse rates overspreads 70+ F surface dewpoints. The approach of an MCV from the remains of an earlier MCS will support convective initiation later this afternoon around and just east of the KC Metropolitan area. Elongated and curved hodographs (especially in the low-levels) will encourage multicell and supercell structures initially. While damaging gusts are the main threat, locally backed low-level winds ahead of the MCV track may encourage a localized tornado threat for a few hours. However, storms should merge into one or more MCSs later this afternoon, with severe gusts the primary concern. Across the southeast, thunderstorm clusters should develop along the eastern periphery of the upper ridge. Given rich low-level moisture and strong buoyancy (with the 16Z mesoanalysis already showing up to 5000 J/kg SBCAPE in place), water-loaded downdrafts may accompany the stronger storm cores, and at least isolated damaging gusts are possible later this afternoon. ....Central into the Southern High Plains... Upslope flow induced by a surface lee trough, along with diurnal heating, will support the development of at least isolated to potentially scattered thunderstorms late this afternoon, from western SD to the TX Panhandle. A plume of 7-8 C/km mid-level lapse rates will advect over the central High Plains in tandem with the ejection of a subtle 700 mb impulse. 2000+ J/kg MLCAPE and an increase in deep-layer shear will result, with modestly lengthening hodographs (and 40 kts of effective bulk shear) expected. Multicells and supercells are expected to be the initial storm modes, with both severe hail wind the primary threats. By evening though, weak low-level shear should encourage outflow and subsequent cold pool mergers, with severe gusts then becoming the dominant severe threat. A few outflow-dominant thunderstorms may also develop along the surface trough across portions of the southern High Plains by afternoon peak heating. These storms will develop atop a dry, mixed boundary layer, with a couple of severe gusts possible. $$ = = = 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) .