Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Aug 13 2023 17:33:50 ACUS02 KWNS 131733 SWODY2 SPC AC 131732 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1232 PM CDT Sun Aug 13 2023 Valid 141200Z - 151200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN KENTUCKY AND TENNESSEE INTO THE MID-ATLANTIC STATES... ....SUMMARY... Severe thunderstorms are possible Monday afternoon and evening across portions of Kentucky and Tennessee, extending north and east to the Mid-Atlantic States. ....Synopsis... A mid/upper shortwave trough oriented from the Upper Midwest to the southern Plains will develop eastward, extending from the eastern Great Lakes to the Mid-South by Tuesday morning. This will bring an belt of enhanced deep-layer southwesterly flow stretching across the Ohio Valley vicinity to the Mid-Atlantic and southern New England. At the surface, low pressure in the vicinity of eastern IA at the beginning of the period will track east to Lake Erie by 12z Tuesday. A cold front attendant to the low will shift east/southeast, extending from eastern IL to northern TX by late afternoon. This front will continue east/southeast through the overnight hours, becoming aligned along the central/southern Appalachians to south TX. A pre-frontal trough is forecast ahead of the main cold front and will become the main focus for strong/severe thunderstorm development (along with any outflow/MCVs associated with prior day's or ongoing morning convection) from KY/TN eastward. Another band of strong/severe thunderstorms attendant to the synoptic cold front and surface low are possible across parts of northern IL/far southern WI eastward across southern Lower MI/IN and northern/western OH from Monday morning into the early evening. ....OH/TN Valley vicinity to the Mid-Atlantic... Convection will likely be ongoing Monday morning across the Lower OH Valley in association with a lead shortwave impulse ahead of the main mid/upper trough. This cluster/MCS will spread east/northeast across WV/VA and southern PA through the afternoon and over the Delaware Valley during the evening. Outflow from morning convection may sag southward into Middle/eastern TN and become a focus for additional diurnal convection from the Cumberland Plateau eastward into the Carolinas. A warm front will be draped across northern MD into southern NJ. To the south of the warm front, southwesterly low-level flow will maintain upper 60s to low 70s F dewpoints, contributing to 1500-2500 J/kg MLCAPE (locally higher possible across eastern KY into TN). Moderate to strong vertical shear and steep low-level lapse rates will support a damaging wind risk from eastern KY into WV and the Mid-Atlantic. Where low-level flow is expected to remain more southeasterly in the vicinity warm front in the Delmarva vicinity, a locally higher tornado risk is possible. Further south across TN into the Carolinas, large-scale ascent will be somewhat weaker. However, moderate to strong instability, steep low-level lapse rates and modest vertical shear will support a risk for damaging winds. The greatest concentration of severe gusts is expected across parts of Middle into eastern TN. ....Lake Michigan vicinity into western OH... Beneath the core of the main upper trough and surface low, a tongue of boundary-layer moisture (dewpoints in the 60s) will arc westward from eastern OH to far eastern IA and southern WI/MI. This will result in a narrow corridor of MLCAPE up to 1000 J/kg. Within this cold core setup, enhanced low-level shear along a warm front will lead to enlarged low-level hodographs, becoming elongated above 2 km. This could support a couple of brief tornadoes and/or strong gusts from stronger cells from late morning into the afternoon. If any organized strong/deeper updrafts can be maintained, isolated hail to near 1 inch also will be possible. ...Leitman.. 08/13/2023 $$ = = = 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) .