Subj : MESO: Mesoscale Discussion 1286 To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jun 26 2023 20:24:53 ACUS11 KWNS 262024 SWOMCD SPC MCD 262024=20 SDZ000-NEZ000-MTZ000-WYZ000-262300- Mesoscale Discussion 1286 NWS Storm Prediction Center Norman OK 0324 PM CDT Mon Jun 26 2023 Areas affected...portions of northern Wyoming...far southeastern Montana...far western South Dakota Concerning...Severe potential...Watch possible=20 Valid 262024Z - 262300Z Probability of Watch Issuance...60 percent SUMMARY...The severe threat is increasing across portions of the northern High Plains. A few supercells may develop, supporting a risk for large hail (including an instance or two of 2+ inch stones), as well as a couple of severe gusts. Convective trends are being monitored for the need of a Severe Thunderstorm Watch issuance later this afternoon. DISCUSSION...MRMS mosaic radar imagery and satellite data suggests that convection is gradually deepening along the higher terrain of the Rockies. Though convection has yet to move off of the higher terrain, stronger forcing should begin to overspread the northern High Plains in the next few hours in association with an approaching 500 mb vort max over northwestern UT. While low-level moisture is not overly rich, 8+ C/km lapse rates from the surface to 500 mb is supporting 2000+ J/kg SBCAPE/MUCAPE, which is adequate for supercell development given the presence of 40+ kt effective bulk shear values (driven by straight, long hodographs). The deep-layer speed shear may support sufficient enough hail growth for stones to exceed 1 inches in diameter, with a couple of 2+ inch diameter stones possible. A few severe gusts may also occur with the heavier supercell precipitation cores given the steep low-level lapse rates. It is unclear exactly when a significant uptick in convective intensity and relatively robust supercell development will occur. It is possible that such development may not occur for at least a few more hours. Nonetheless, Severe Thunderstorm Watch issuance will likely be needed at some point this afternoon or evening and convective trends are being monitored closely for more precise timing of the watch issuance. ...Squitieri/Grams.. 06/26/2023 ....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!8WoAe9Ms-hYfCsgrdThX8fEDYmabJNvlJYnAFOMejV9FacUJ-Uzhv2CuHyk_XZSIs2ouiRizE= FXhKYGfv288z_hVn5g$ for graphic product... ATTN...WFO...UNR...CYS...BYZ...RIW... LAT...LON 43391037 44540896 45490731 45640592 45640456 45070351 44510309 44180317 43120370 42680452 42390547 42400736 42570816 43391037=20 =3D =3D =3D 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) .