Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri May 16 2025 06:00:19 ACUS01 KWNS 160600 SWODY1 SPC AC 160558 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Fri May 16 2025 Valid 161200Z - 171200Z ....THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF KENTUCKY...NORTHERN AND WESTERN TENNESSEE...SOUTHEAST MISSOURI...FAR SOUTHERN ILLINOIS...SOUTHERN INDIANA...FAR SOUTHWEST OHIO... ....SUMMARY... A regional outbreak of severe thunderstorms is likely this afternoon into tonight across parts of the mid Mississippi, Ohio and Tennessee Valleys. This will include intense supercells associated with tornadoes, large hail and wind damage. Several strong tornadoes are expected, and a long-track high-end tornado will be possible. From the evening into the overnight, a bowing line segment is expected to form with potential for tornadoes and damaging winds, some possibly greater than 75 mph. ....Mid Mississippi and Ohio Valley/Tennessee Valley... A negatively-tilted mid-level trough will move through the Upper Midwest and mid Mississippi Valley today, as an associated 75 to 90 knot mid-level jet translates northeastward into the Ozarks. At the surface, a low will move into the western Great Lakes, as a cold front advances eastward into the mid Mississippi Valley. A very moist airmass will remain in place ahead of the front, extending eastward into the Ohio and Tennessee Valleys. Across this airmass, surface dewpoints will be in the upper 60s and lower 70s F. Warming surface temperatures will result in moderate to strong destabilization across much of the moist sector by afternoon. An area of low-level convergence is expected to become increasingly focused from the Ozarks into the mid Mississippi Valley. This will result in the initiation of scattered strong to severe storms around midday. Several convective clusters are expected to organize and move eastward into the lower Ohio Valley during the afternoon. Storm coverage will expand markedly during the late afternoon and early evening as low-level flow increases across the region. Concerning the thermodynamic environment, a pristine airmass is expected to be in place by afternoon. Model forecasts are in good agreement that MLCAPE will peak from 3000 to 4000 J/kg from parts of the Ozarks eastward into the Ohio and Tennessee Valleys. As instability increases, deep-layer shear and lift are also expected to increase as a mid-level jet approaches from the west. Ahead of this feature, an 850 mb jet is forecast to develop over the mid Mississippi Valley. This jet will gradually increase in strength into the 45 to 65 knot range, moving eastward into western Kentucky by late afternoon. Near the axis of the low-level jet at Paducah, RAP forecast soundings at 23Z have MLCAPE near 3500 J/kg, 0-6 km shear around 60 knots, and low to mid-level lapse rates near 7 C/km. 0-3 km helicity is forecast to be between 225 and 250 m2/s2. This environment will support supercells and tornadoes. Several strong tornadoes appear likely, and a high-end long-track tornado will be possible from far southeast Missouri, into southern Illinois and southern Indiana, southward into western Kentucky and far northern Tennessee. During the late afternoon, storm coverage is expected to become widespread across the moist sector. Several supercell clusters will move eastward from the mid Mississippi Valley into the Ohio and Tennessee Valleys. Steep mid-level lapse rates will promote large hail development. The more intense cores may have hailstones between 2 and 4 inches in diameter. Supercells will also be capable of producing damaging wind gusts. During the early evening, the wind-damage threat is expected to increase as some of the convective clusters gradually transition into more linear structures. Winds could exceed 75 mph along the leading edge of these faster-moving bowing line segments. During the evening, multiple bow echos are expected to form that will result in extensive wind damage swaths. Wind damage is expected across a broad area, including parts of the mid Mississippi, Ohio and Tennessee Valleys into the central Appalachian mountains. ....Ark-La-Tex/Lower Mississippi Valley... A very moist airmass will be in place today across the Ark-La-Tex and lower Mississippi Valley. Surface dewpoints in the lower to mid 70s F will result in moderate to strong destabilization across much of this airmass. A capping inversion is expected to be in place for much of the day, but should weaken late in the afternoon as a mid-level jet moves eastward into the mid Mississippi Valley. The southern edge of the jet will help to increase large-scale ascent, aiding convective development. In response, a few clusters of storms will form and move eastward into the lower Mississippi Valley during the late afternoon and early evening. In areas that strongly destabilize, storms could be capable of producing large hail and wind damage. Hailstones greater than 2 inches in diameter will be possible with intense supercell cores. ...Broyles/Weinman.. 05/16/2025 $$ = = = 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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .