Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jan 12 2023 01:01:18 ACUS01 KWNS 120101 SWODY1 SPC AC 120059 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0659 PM CST Wed Jan 11 2023 Valid 120100Z - 121200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TONIGHT ACROSS PARTS OF NORTHEASTERN ARKANSAS...SOUTHEASTERN MISSOURI...NORTHWESTERN TENNESSEE...WESTERN KENTUCK AND SOUTHERN ILINOIS... ....SUMMARY... A few severe thunderstorms may develop later tonight across parts of the Ozark Plateau into lower Ohio Valley, accompanied by a risk for large hail and potential to produce a tornado or two. ....01Z Update... Downstream of building mid-level ridging across the Pacific coast through Intermountain West vicinity, a vigorous short wave trough within one branch of downstream westerlies is in the process of digging to the lee of the southern Rockies. This perturbation appears to include one 500 mb speed maximum in excess of 70 kt now beginning to shift into and through the Ark-La-Tex vicinity. A more intense (90-100 kt) speed maximum is digging upstream, across the Texas South Plains vicinity. Although models suggest that the trailing speed maximum will weaken some as it redevelops to the east of mid-level trough axis overnight, a belt of 80-90+ kt southwesterly 500 mb flow may develop across southwest through central Arkansas into the Missouri Bootheel vicinity. As this occurs, a modest surface cyclone now northwest of Oklahoma City is forecast to be maintained, and develop east-northeastward into northwestern Arkansas by 12/06Z, before continuing into the vicinity of the confluence of the Mississippi and Ohio Rivers by 12Z Thursday morning. To this point, the lack of low-level moisture return to the southern Great Plains has minimized convective potential, but large-scale forcing for ascent is beginning to encounter better, albeit still modest, low-level moisture now advecting across parts of southeastern/eastern Texas and the lower Mississippi Valley. Isolated thunderstorm activity has recently developed across parts of southeastern Oklahoma, and it appears that this will continue to gradually increase northward and east-northeastward into and through the lower Ohio Valley by daybreak Tuesday, aided by lift associated with lower/mid tropospheric warm advection. Much of this convection may remain rooted above a substantive near-surface stable layer, along and north of a developing warm front to the east-northeast of the migratory cyclone. Even in the warm sector, it remains unclear whether a residual shallow near-surface stable layer will impact convective potential as mid-level inhibition gradually weakens. However, it does appear that there could be a developing corridor with potential for vigorous boundary-layer based thunderstorm development overnight, generally near the surface warm front, just ahead of the surface low, and near the exit region of the strengthening mid-level jet. This may include the risk for a couple of supercells posing a risk for large hail and potential to produce a tornado or two. ...Kerr.. 01/12/2023 $$ = = = 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) .