Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jan 02 2023 20:00:02 ACUS01 KWNS 021959 SWODY1 SPC AC 021958 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0158 PM CST Mon Jan 02 2023 Valid 022000Z - 031200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EAST TEXAS/OKLAHOMA INTO ARKANSAS/NORTHERN LOUISIANA AND THE MID-SOUTH... ....SUMMARY... All severe thunderstorm hazards remain possible this afternoon through tonight over eastern Oklahoma and the Arklatex region into southeastern Kansas, the Ozarks, and parts of the Mid-South. Tornadoes (some strong) and damaging gusts will be the greatest threats, but some large hail may also occur. ....20Z Update... The only change with this update was to expand severe probabilities slightly farther west in central OK and north-central TX. Recent trends in observational data and short-term model guidance suggest that convection will probably initiate across this area within the next couple of hours. Given the rather steep mid-level lapse rates noted from the 18Z observed sounding from OUN/FWD, large hail may be the primary severe threat initially. As these thunderstorms encounter greater low-level moisture and favorable boundary-layer shear in east TX/OK, they should pose a threat for tornadoes. Some of the tornadoes could be strong, particularly from the ArkLaTex into central AR this evening/tonight as a southerly low-level jet strengthens and enhances the low-level hodograph. An eventual transition to a more cluster/linear mode is still anticipated with eastward extent into the lower MS Valley, with a continued threat for embedded tornadoes and scattered damaging winds. ...Gleason.. 01/02/2023 ..PREV DISCUSSION... /ISSUED 1029 AM CST Mon Jan 02 2023/ ....Synopsis... A midlevel cyclone, currently evident in water vapor imagery over eastern UT/western CO, will evolve gradually eastward today, reaching northern KS/southern NE by 12Z. Peripheral to this cyclone, a strong midlevel southwesterly speed max will round the base of the associated large-scale trough, overspreading the central/southern Plains and emerging over the Middle MS Valley by 12Z. Concurrently, an elongated/ill-defined surface low -- initially centered over eastern NM/TX Panhandle -- will lift east-northeastward across western OK into central KS by 00Z. At the same time, a warm front extending eastward from the surface low across northern OK into southern MO will move northward today, eventually extending from eastern KS into IN by 00Z. A Pacific cold front extending southward from the surface low will advance eastward into central OK southward through west-central TX by 00Z, before continuing eastward toward the Middle MS Valley southwestward into south-central TX by 12Z. In response to these developments, a 40-50-kt southerly low-level jet (sampled by regional VWPs) will lift northward from southeast TX through the Arklatex this afternoon, before continuing north-northeastward and strengthening over the Middle MS Valley and eventually the Lower OH River Valley. ....Eastern OK/TX/KS to the Mid-South... Along the nose of the southerly low-level jet, isolated to widely scattered thunderstorms are spreading northward across the Arklatex, while additional storms are developing within the warm frontal zone near the Middle MS Valley. While the storms to the north should generally continue northward and outpace the warm sector, the evolving storms to the south will have plenty of residence time across the expansive warm sector -- characterized by middle/upper 60s boundary-layer dewpoints and upper 60s/lower 70s surface temperatures. 40-50 kt of effective shear and gradually enlarging low-level hodographs will conditionally support discrete surface-based supercells capable of all hazards with this first round of convection, however, lingering capping and a lack of surface heating cast uncertainty on how robust this initial activity will become. As midlevel height falls and an EML continue overspreading the destabilizing warm sector, additional thunderstorm development is expected along the western edge of the richest boundary-layer moisture over northeast TX, before spreading northeastward across the Arklatex by mid-afternoon. These storms should quickly evolve into discrete or semi-discrete surface-based supercells as they impinge on the western edge of the strong low-level jet and upper 60s dewpoints. Large, clockwise-turning low-level hodographs and 1500-2000 J/kg MLCAPE should support several tornadoes (some of which could be strong) with these supercells, along with large hail and damaging gusts. Into the evening time frame, these initially discrete/semi-discrete supercells should evolve into clusters and line segments as they track northeastward across the Mid-South, owing to strengthening large-scale ascent overspreading the warm sector. Tornadoes and large hail are still possible with these storms, though the damaging-wind risk will gradually become an increasing concern. Thereafter, a predominantly linear mode should evolve along the eastward-advancing Pacific cold front into the overnight hours, extending from the Lower OH River Valley southwestward into the Lower MS Valley. Damaging gusts will be the main threat during this period, but strong low-level shear will continue to support embedded tornadoes. $$ = = = 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) .