Subj : DAY3SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jan 09 2023 08:31:27 ACUS03 KWNS 090831 SWODY3 SPC AC 090830 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CST Mon Jan 09 2023 Valid 111200Z - 121200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EAST TEXAS/OKLAHOMA INTO THE LOWER MISSISSIPPI VALLEY AND MID-SOUTH... ....SUMMARY... Isolated severe thunderstorms will be possible Wednesday night through early Thursday morning from parts of east Texas/Oklahoma into the lower Mississippi Valley and Mid-South. ....East Texas/Oklahoma into the Lower Mississippi Valley and Mid-South... An upper trough initially over the Southwest and Great Basin should move eastward across the southern/central Plains Wednesday while eventually transitioning to a closed low. This trough/low is forecast to continue eastward Wednesday night to the lower/mid MS Valley and Mid-South. A surface low centered over the central High Plains should develop eastward in tandem with the upper trough/low through the day, reaching southern MO and the Mid-South by the end of the period. Increasing low-level warm advection will advance a partially modified Gulf airmass northward across portions of east TX/OK into the lower MS Valley ahead of the surface low. A stout cap associated with an EML emanating from the western CONUS and northern Mexico will likely inhibit convective development across the warm sector through at least Wednesday afternoon. By Wednesday night, mid-level height falls and strong ascent preceding the upper trough/low will begin to overspread the warm sector and erode the cap. Most guidance suggests that convection will develop along/ahead of a cold front around 12/06Z from parts of east TX/OK into AR/LA. There is still some uncertainty regarding the quality of low-level moisture. But, at least upper 50s to low 60s surface dewpoints should be present across these areas. Cooling temperatures aloft with the approach of the upper trough/low and the presence of rather steep mid-level lapse rates should aid in the development of at least weak boundary-layer instability. Deep-layer shear of 40-50+ kt will easily support updraft organization, including the potential for a supercell or two. Convection should have a tendency to grow upscale along or just ahead of the cold front as both advance east-southeastward over the lower MS Valley and Mid-South through the end of the period. Isolated damaging winds will probably be the main severe risk with any surface-based convection, but some threat for hail may exist with initial thunderstorm development given the favorable lapse rates aloft. A couple tornadoes also appear possible, even though low-level flow should veer to a more southwesterly component with time late Wednesday night into early Thursday morning. The northward extent of appreciable severe risk is uncertain, given differences in guidance regarding the eastward progression of the upper trough/low and strength/placement of the surface low. Still, have opted to include much of the Mid-South in the Marginal Risk, as it appears that at least upper 50s dewpoints will be present there. Lingering concerns regarding instability, the quality of low-level moisture, and cap strength preclude greater severe probabilities at this time. ...Gleason.. 01/09/2023 $$ = = = 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) .