Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Apr 07 2023 12:44:28 ACUS01 KWNS 071244 SWODY1 SPC AC 071243 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0743 AM CDT Fri Apr 07 2023 Valid 071300Z - 081200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE LOWER MISSISSIPPI DELTA REGION TODAY... ....SUMMARY... Isolated severe hail and thunderstorm gusts are possible in parts of the lower Mississippi Delta region today. ....Synopsis... In mid/upper levels, a progressive, somewhat amplified, northern- stream pattern will deamplify gradually through the period and into day-2. This will occur as a strong, positively tilted trough departs Atlantic Canada, and a negatively tilted trough now over the Pacific Coast moves inland and weakens slowly. A weak southern- stream trough, bracketed by broadly cyclonic flow, was evident in moisture-channel imagery across parts of AZ, Sonora, and the Gulf of California. This perturbation should weaken today as it moves northeastward across northwestern MX toward the Rio Grande Valley of TX and NM. To its east, a series of relatively minor shortwaves and vorticity maxima -- some convectively induced/enhanced -- are embedded in southwesterlies from northeastern MX across South TX, the northwest Gulf, and the lower Mississippi Valley region. One such feature -- initially apparent over south-central TX to coastal Tamaulipas -- should move northeastward toward LA today, then weaken over the MS/AL region and nearby Gulf waters tonight. At the surface, 11Z analysis showed a cold front over eastern/ central NC, northern GA, central AL, and near-coastal MS, becoming quasistationary across southeastern LA and the northwestern Gulf offshore from TX. Abundant precip along and north of the LA/Gulf segment of this boundary will continue to reinforce it, with resulting southward net drift likely through the period. By 12Z, the cold front should reach the GA Coast, FL Panhandle, coastal MS, extreme southeastern LA, and slightly farther south of the Gulf than present position. ....Lower Delta... Widely scattered to scattered thunderstorms are expected through much of today and into this evening on either side of the front, with activity along and to its south offering a marginal threat for damaging to briefly severe gusts. Isolated severe hail also may be noted near and south of the boundary. The warm-sector air mass across the region will remain characterized by favorable low-level moisture, with surface dewpoints commonly in the 68-73 F range, mean mixing ratios around 15 g/kg, and PW near 1.5 inches. Though perhaps aided subtly by weak large-scale lift preceding the northwest Gulf shortwave trough, mid/upper-level lapse rates should remain modest, offset somewhat by the rich moisture and weak diurnal heating under cloud cover. Peak MLCAPE around 1500 J/kg is expected, with little or no MLCINH for much of the day. This should enable development in the warm sector as well as along the front. Though prefrontal winds will veer with height, weak speeds in low/middle levels will keep hodographs small and effective-shear magnitudes around 30-35 kt. This, along with substantially stronger anvil-level/venting flow, supports episodic organized multicells and pulse storms offering a marginal severe threat. Essentially boundary-parallel flow aloft, underlain by a very slow-moving frontal/outflow combination, will lead to training of convection along and north of the boundary, with localized anafrontal effects. ...Edwards/Smith.. 04/07/2023 $$ = = = 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) .