Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Aug 15 2024 16:25:50 ACUS01 KWNS 151625 SWODY1 SPC AC 151624 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Thu Aug 15 2024 Valid 151630Z - 161200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATER THIS AFTERNOON INTO EARLY TONIGHT FROM CENTRAL OK TO THE MID MS VALLEY... ....SUMMARY... Scattered severe thunderstorms are possible across parts of the Midwest through tonight. Severe gusts capable of wind damage and large hail are the primary risks with the stronger thunderstorms. ....Mid MS Valley this afternoon/evening... The remnants of overnight convection, and an associated/lead shortwave trough, are moving across southern MO/IL. Though these storms will likely weaken through midday, a diffuse outflow/differential heating zone may help focus additional thunderstorm development this afternoon. Southern MO to southern IL will be along the southern fringe of the stronger midlevel flow, where a mix of multicell clusters and possibly a supercell or two capable of producing damaging winds (60-70 mph) and isolated large hail (1-1.5 inches in diameter) will be possible later this afternoon/evening. The primary midlevel shortwave trough will progress eastward from NE/SD toward the upper MS Valley by tonight, in conjunction with a surface cold front. Weak, ongoing convection across north central and northeast NE reflects the zone of ascent spreading east-southeastward through the afternoon, toward the destabilizing warm sector in the wake of overnight convection across northern MO/southern IA. Though timing is still a bit uncertain, thunderstorm development appears probable late this afternoon or this evening across eastern NE and especially near the MO/IA border. Relatively long/straight hodographs, midlevel lapse rates near 7.5 C/km and MLCAPE in excess of 2000 J/kg will support supercells capable of producing large hail (1-2 inches in diameter) and damaging gusts (60-75 mph). Some upscale growth into a cluster may also occur as the storms spread east-southeastward toward IL tonight. ....OK this afternoon/evening... Strong surface heating is ongoing across central OK along a weak pre-frontal trough. Mid-upper flow will be weak this far southwest, but deep mixing with surface heating will contribute to steep low-level lapse rates and MLCAPE of 1500 J/kg or greater with minimal convective inhibition. Scattered thunderstorms are expected along this trough by mid-late afternoon, when isolated damaging downburst winds (60-75 mph) will be possible. ....New England this afternoon... To the west of a closed low over Nova Scotia, an embedded shortwave trough is rotating southward over New England with ongoing convection in southwest ME and NH. Surface heating/destabilization on the western/southern fringes of the ongoing storms will likely contribute to additional thunderstorm development this afternoon. Moderate buoyancy and steepening low-level lapse rates, as well as cool midlevel temperatures (-14 to -15 C at 500 mb), will support the potential for isolated wind damage with 45-60 mph gusts and isolated hail approaching 1 inch in diameter with multicell clusters. See MD #1557 for additional information. ....Northern Rockies this afternoon/evening... A midlevel trough will eject east-northeastward over ID/southwest MT/extreme northwest WY through this evening. Steep lapse rates and modest PW (near or less than 0.75 inches) will support high-based thunderstorm development this afternoon in the zone of ascent preceding the midlevel trough. Strong outflow gusts (50-60 mph) will be the main concern. ...Thompson/Weinman.. 08/15/2024 $$ = = = 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) .