Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jul 01 2023 19:50:59 ACUS01 KWNS 011950 SWODY1 SPC AC 011949 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0249 PM CDT Sat Jul 01 2023 Valid 012000Z - 021200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON INTO THIS EVENING ACROSS PARTS OF EAST CENTRAL AND SOUTHEAST MISSOURI...SOUTHERN ILLINOIS...SOUTHERN INDIANA AND WESTERN INTO CENTRAL KENTUCKY... ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE WEST TEXAS PERMIAN BASIN... ....SUMMARY... Thunderstorms may gradually consolidate and organize across parts of the middle Mississippi into lower Ohio Valley late this afternoon, accompanied by increasing potential for damaging wind gusts and perhaps a couple of tornadoes into this evening. ....20Z Update... Adjustments have been made to better account for the progression of synoptic and sub-synoptic features and associated trends concerning instability. An increase in thunderstorm development is ongoing across east central and southeast Missouri, aided by forcing associated with a smaller-scale perturbation/speed maximum within positively-tilted larger-scale mid-level troughing gradually shifting east of the central Great Plains. In the presence of strong deep-layer shear beneath a belt of 40+ kt southwesterly 500 mb flow across southeastern Missouri into south central Illinois, it still seems probable that upscale growing convection will become increasingly organized while propagating east of the Mississippi River late this afternoon. Easterly near-surface inflow into updrafts will be characterized by seasonably moist air with moderately large CAPE across southeastern Missouri through southern Illinois, Indiana and western Kentucky. Farther east, toward the Allegheny and Cumberland Plateau, prior convective outflow is maintaining considerable influence and potential for substantive destabilization to maintain activity remains more unclear. ...Kerr.. 07/01/2023 ..PREV DISCUSSION... /ISSUED 1129 AM CDT Sat Jul 01 2023/ ....Mid MS/OH Valleys... A modestly amplified shortwave trough over western NE/KS will progress into IA/MO by tonight, as embedded, convectively enhanced perturbations rotate around its southern and eastern periphery. One such perturbation near the Ozark Plateau will aid in scattered thunderstorm development as it impinges on the Mid-MS Valley. This activity will form within a pronounced differential boundary-layer heating/buoyancy gradient amid large MLCAPE of 3000-4000 J/kg in the undisturbed warm sector over the Mid-South. Within a belt of 35-45 kt mid-level west-southwesterlies, initial supercells/clusters congealing into a forward-propagating linear MCS appears probable. Large hail will be possible, mainly early, but the predominant threat should be damaging wind swaths towards the central OH Valley. A couple of embedded tornadoes will also be possible, mainly focused along/just north of the residual outflow boundary arcing west from ongoing convection over central KY. ....Permian Basin... Weak convergence along a convectively enhanced cold front, in combination with a narrow corridor of stronger boundary-layer heating between the front and thicker clouds within the southern-stream closer to the Big Bend, should yield a rather confined corridor of MLCAPE approaching 2500 J/kg in the late afternoon. Deep-layer shear will be modest and convection will probably be slow-moving to the south-southeast but a few severe outflow gusts and isolated large hail will be possible. ....Lee of the central/southern Appalachians... There is some potential for intensification of isolated to scattered storms along residual outflows and a weak surface trough just east of the Blue Ridge, as the low levels warm this afternoon. Mid-level lapse rates will remain weak north of southwest VA, while diffluent mid-level flow in the lee of the central Appalachians will generally hold effective bulk shear below 25 kt north of southwest VA. Localized damaging winds and perhaps marginally severe hail will be the main threats. ....PA/NY... Subtle/embedded perturbations will move over the lower Great Lakes region today, around the southern periphery of the shortwave trough centered on the Ontario-Quebec border. Surface heating in cloud breaks and boundary-layer dew points in the 60s will support MLCAPE of 1000-1500 J/kg east of the influence of the Lower Great Lakes. Mid-level lapse rates will not be steep, but some modest enhancement to mid-upper flow could be sufficient for a few semi-organized clusters capable of producing isolated wind damage for a few hours centered on late afternoon. ....Southern MT to ND... Though forcing for ascent will be weak, at least isolated thunderstorm development will be possible this afternoon/evening from edge of the higher terrain in southern MT northeastward along a weak pre-frontal trough into ND. Surface heating/deep mixing will drive inverted-V profiles with MLCAPE of 500-1500 J/kg. Weak flow supports relatively slow-moving cells/clusters capable of producing isolated strong-severe outflow gusts. $$ = = = 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) .