Subj : DAY2SVR: Nws Storm Predic To : All From : Mike Powell Date : Sat Aug 12 2023 08:11:00 ACUS02 KWNS 120600 SWODY2 SPC AC 120559 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Sat Aug 12 2023 Valid 131200Z - 141200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF THE SOUTHERN AND CENTRAL PLAINS INTO THE MIDDLE MS AND LOWER OH VALLEYS... ....SUMMARY... Severe thunderstorms are possible Sunday afternoon through Sunday night from portions of the southern and central Plains into the Middle Mississippi and Lower Ohio Valleys. ....Northern/Central Plains into the Mid MS and Lower OH Valleys... A strong shortwave trough is forecast to progress southeastward across the northern and central Plains on Sunday, ending the period extended from central MN southeastward into north-central KS. An associated surface low is expected to begin the period near the central SD/NE border before then progressing eastward throughout the day, reaching southeast MN by late Sunday night/early Monday morning. As this low moves eastward, an attendant cold front will sweep southeastward across the central Plains. By 00Z this front is expected to extend from the low over west-central MN southward to a triple point near the IA/NE/MO border intersection and then southwestward across KS into the northern TX Panhandle. Showers and thunderstorms will likely be ongoing at the beginning of the period near the surface low over the middle MO Valley. Buoyancy will be modest, but moderate vertical shear could support a strong storm or two. Early period activity is expected farther south across the Lower MO Valley/Ozarks as well. This southern activity will be the remnant of an overnight convective line across KS and OK. Current expectation is for these storms to diminish by late morning/early afternoon as the low-level jet weakens and continue eastward. However, outflow associated with this cluster could play a significant role in the severe potential across the Lower MO and Mid MS Valley later. The cold front is forecast to continue progressing eastward/southeastward during the afternoon, and thunderstorm development is anticipated as it reaches east-central NE and western IA. Moderate buoyancy and shear could support a few stronger storms, with damaging gusts as the primary risk. As the front continues southeastward, the residual outflow initially across southeast KS and southern MO is expected to begin returning northward as a warm front. By the late afternoon/evening, open warm-sector development is possible across eastern KS and central/southern MO, with storm intensity likely increasing along the front as well. Primary threat for storms along the front is damaging gusts, while all severe hazards are possible with any warm-sector storms. Complex convective evolution is possible during the evening as the cold front, and its associated thunderstorms, interact with the warm front, and its associated warm-sector storms in the southern MO/southern IL vicinity. Some potential for upscale growth into an organized convective system exists, but if and where this occurs is still fairly uncertain. Higher wind probabilities may be needed in later outlook if a corridor of MCS progression becomes more predictable. Even if an organized MCS doesn't develop, some severe potential will still extend through the Mid MS Valley into the Lower OH Valley throughout the evening and overnight. ....Southern High Plains into southern KS and northern OK... Thunderstorm development appears possible on both the cold front moving across western KS as well as an outflow boundary that will likely be in place from a preceding MCS. Strong heating will help destabilize the airmass, with moderate buoyancy and little to no convective inhibition in place by the late afternoon. A belt of stronger mid-level flow will extend across this area as well, supporting 40 to 50 kt of effective bulk shear. These environmental conditions will support robust, organized updrafts capable of large hail and damaging gusts. Some potential for cold-pool amalgamation is possible, with the resultant convective line moving likely eastward/northeastward into more of south-central KS and north-central OK. ....Eastern New England... Low to mid 60s dewpoints are expected to be in place across the region ahead of a weak cold front. Airmass destabilization is anticipated ahead of this front as temperatures climb into the upper 70s and low 80s. Lift along the front will be augmented by large-scale ascent from a glancing low-amplitude shortwave trough moving across far southern Quebec and northern ME. Interaction between this lift and a destabilized airmass is forecast to result in thunderstorm development along and ahead of the front. Vertical shear should be strong enough to support a few organized storms capable of hail and/or damaging gusts. ...Mosier.. 08/12/2023 $$ --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .