Subj : DAY2SVR: Nws Storm Predic To : All From : Mike Powell Date : Mon Jul 24 2023 16:23:00 ACUS02 KWNS 241653 SWODY2 SPC AC 241652 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1152 AM CDT Mon Jul 24 2023 Valid 251200Z - 261200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE EASTERN DAKOTAS INTO NORTHERN NEBRASKA...AND THE MID-ATLANTIC VICINITY... ....SUMMARY... Isolated to widely scattered severe thunderstorms are possible from Nebraska into the Dakotas, and across portions of the Mid-Atlantic vicinity Tuesday afternoon and evening. Damaging gusts and hail will be the main hazards with these storms. ....Mid-Atlantic Vicinity... A large scale mid/upper trough oriented from the lower Great Lakes to the central Appalachians will pivot east across the Mid-Atlantic and Northeast on Tuesday. Large scale ascent coupled with modest vertical shear (effective shear magnitudes around 30 kt) atop a seasonally moist/unstable airmass will support scattered strong to severe thunderstorms from early afternoon into early evening. Elongated/straight hodographs amid large instability above 850 mb and increasing westerlies to around 35 kt between 3-6 km suggest isolated severe hail will be possible with semi-discrete cells, especially around the Delmarva/Chesapeake Bay vicinity where midlevel lapse rates are forecast to be steepest (around 6.5-7 C/km). Strong heating will aid in steepening low-level lapse rates, and low-level winds will remain fairly light. This will promote potential for strong outflow and isolated damaging gusts. Some guidance suggests a forward propagating cluster may develop via consolidating outflow across the Chesapeake Bay vicinity late afternoon/early evening. As a result of these factors, the Marginal risk (level 1 of 5) has been expanded across the Mid-Atlantic and a Slight risk (level 2 of 5) introduced across the Delmarva vicinity. ....Northern/Central Plains... A mid/upper shortwave impulse will migrate eastward from the northern Plains to the Great Lakes vicinity on Tuesday. While an upper ridge will be oriented over the Plains, this shortwave will provide large-scale support for thunderstorm development by late afternoon across the central Dakotas. Southerly low-level flow will transport/maintain 60s F dewpoints. Initially strong capping will be overcome by large-scale ascent provided by the midlevel shortwave and persistent low-level warm advection. Isolated to scattered thunderstorms will develop by late afternoon. Effective shear magnitudes of 40+ kt combined with vertically veering wind profiles will support initial, high-based supercells. Steep midlevel lapse rates and elongated hodographs suggest large hail will be possible with initial semi-discrete convection. A well-mixed boundary-layer is forecast as temperatures warm into the 90s and will aid in strong outflow winds. With time, some guidance suggests a forward propagating MCS may develop and move across southeast ND/eastern SD and parts of northeast NE during the evening. If this occurs, damaging wind potential may persist into the nighttime hours. Vertical shear will weaken considerably with southward extent, though a tongue of modest boundary-layer moisture will extend into northeast CO/northwest KS, supporting moderate destabilization. Isolated, high-based convection is possible, posing mainly a risk for strong outflow winds for a few hours during the late afternoon/early evening. ...Leitman.. 07/24/2023 $$ --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .