Subj : DAY2SVR: Marginal Risk To : All From : Mike Powell Date : Wed Sep 06 2023 06:23:00 ACUS02 KWNS 060549 SWODY2 SPC AC 060548 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Wed Sep 06 2023 Valid 071200Z - 081200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHEAST...MID-ATLANTIC...ARK-LA-TEX...SABINE RIVER VALLEY...LOWER MISSISSIPPI VALLEY...CENTRAL PLAINS AND NORTHERN PLAINS... ....SUMMARY... Thunderstorms, associated with marginally severe wind gusts and hail, will be possible on Thursday across parts of the Northeast and Mid-Atlantic. Additional storms with a marginal severe threat may develop in parts of the Great Plains, Ark-La-Tex, Sabine Valley, and lower Mississippi Valley. ....Northeast/Mid-Atlantic... An upper-level trough, and an associated cold front, will move eastward into the central Great Lakes, middle Ohio Valley and southern Appalachians on Thursday. Ahead of the front, a moist airmass will be in place with surface dewpoints mostly in the 60s F. As surface temperatures warm on Thursday, scattered thunderstorm development is expected across much of the Northeast and Mid-Atlantic region. Although deep-layer shear is forecast to be relatively weak, low-level lapse rates will become steep in the afternoon in many areas. This could be favorable for marginally severe gusts with multicells that form in areas with the strongest surface heating. ....Southern Plains/Ark-La-Tex/Sabine and Lower Mississippi Valleys... A cluster of strong thunderstorms is forecast to be ongoing at the start of the period in the Ark-La-Tex. This cluster is forecast to move south-southeastward into the Sabine River and lower Mississippi Valleys by afternoon. A marginal wind-damage threat will be possible with the stronger embedded cores. Further north-northwest, an axis of instability is forecast to set up during the late afternoon and evening from the Ark-La-Tex to central Oklahoma. A low-level jet is forecast to strengthen across the southern Plains. On the nose of the low-level jet, elevated convection is forecast to develop along the instability gradient during the late evening, and persist into the overnight period from eastern Oklahoma into western Arkansas. NAM forecast soundings along the favored convective corridor at 06Z have MUCAPE near 2000 J/kg, and effective shear near 40 knots. This should be favorable for an isolated large-hail threat with the stronger elevated rotating cells. ....Central and Northern Plains.. A minor shortwave is forecast to move into the central and northern Plains on Thursday, as an axis of instability develops across central Nebraska and southern South Dakota. Isolated to scattered thunderstorm development will be possible along and to the east of the instability axis during the late afternoon and early evening. NAM forecast soundings in northeastern Nebraska at 00Z/Friday suggest that MUCAPE could reach the 1000 to 1200 J/kg range. This, combined with moderate deep-layer shear and steep mid-level lapse rates, may be enough for hail with the stronger cores. A few marginally severe gusts will also be possible. ...Broyles.. 09/06/2023 $$ --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .