Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Mar 12 2024 12:32:57 ACUS01 KWNS 121232 SWODY1 SPC AC 121231 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0731 AM CDT Tue Mar 12 2024 Valid 121300Z - 131200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE WESTERN OZARKS/EASTERN KANSAS REGION TO NORTHERN MISSOURI... ....SUMMARY... Isolated severe thunderstorms are possible this afternoon and evening from the western Ozarks/eastern Kansas region to northern Missouri. ....Synopsis... The period begins with a progressive, fairly low-amplitude mid/ upper-level pattern over most of the CONUS. However, a trough now over the West Coast vicinity will strengthen as it moves inland and reaches ID, NV and the lower Colorado River Valley by 12Z tomorrow. This will spread a large field of height falls and generally difluent mid/upper flow across the Great Basin, Intermountain West and Rockies tonight, reaching the High Plains by the end of the period. A broad area of low-end, isolated thunderstorm potential exists ahead of the trough in the West. Ahead of these developments, a preceding shortwave trough -- apparent in moisture-channel imagery over eastern parts of WY/CO/NM -- will move eastward over the central Plains today. This perturbation should reach southeasternmost NE, extreme eastern KS and northeasternmost OK by 00Z, then cross the lower Ohio Valley around 12Z. At the surface, 11Z analysis showed a weak frontal-wave low over west-central KS, south of the associated cyclonic circulation center nearer the KS/NE border. The cyclone center and pressure low should consolidate better today as the frontal wave shifts eastward. By 00Z, the surface low should reach northwestern MO, with trailing trough/weak cold front to northwestern OK, the northern TX Panhandle, and southeastern CO. The low should drift eastward over northern MO through tonight, as the trailing front/trough stall over western OK and the eastern TX Panhandle, then begin shifting north again in a regime of lee cyclogenesis preceding the main western CONUS trough. A dryline -- now analyzed over Coahuila and parts of west TX from about MAF southward, should become better defined today from west-central TX to northeastern OK and extreme eastern KS (near the cold front) as moist advection continues across central TX, eastern OK, and the western Ozark Plateau. ....Ozarks/eastern KS to western/northern MO... Isolated to widely scattered thunderstorms are possible over the outlook area late this afternoon and/or this evening, with a marginal large-hail and damaging-wind threat. The western part of the outlook area is intended more for any late-afternoon development (conditional), with evening activity somewhat more certain over eastern parts. Moisture return will be quite immature across the region, but still potentially sufficient for thunderstorm development, with surface dewpoints generally reaching the mid 40s to low 50s F, east of the dryline and south of the warm front. Cooling aloft and steepening of low/middle-level lapse rates will occur this afternoon as DCVA increases and low-level warm advection continues ahead of the favorably timed shortwave trough. Boundary-layer theta-e advection and diabatic surface heating should boost buoyancy and reduce MLCINH throughout the afternoon, resulting in a narrow plume of about 800-1300 J/kg MLCAPE, atop a well-mixed boundary layer. Daytime initiation, should it occur, would be between the surface moist axis, warm front, and dryline/cold front. Though low-level shear is expected to be favorable for supercells, midlevel winds (generally 400-700 mb) are expected to weaken with northward extent, closer to where low-level forcing is strongest, near the low and frontal triple point. This will reduce effective- shear magnitudes from around 40-50 kt in southern areas (Ozarks vicinity) to less than 30 kt near and north of I-70. Though convection may persist longer in that corridor this evening due to greater instability aloft, and support from the LLJ, its increasingly elevated inflow layer, messier mode and lack of greater moisture will temper severe potential. ...Edwards/Dean.. 03/12/2024 $$ = = = 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) .