SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Sat Oct 18 2025 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE ARKLATEX AND OZARKS INTO PARTS OF THE LOWER/MID MS VALLEYS... ...SUMMARY... Scattered severe thunderstorms are possible today into tonight across parts of the Ark-La-Tex, Ozarks, mid to lower Mississippi and lower Ohio Valleys. Damaging winds, a few tornadoes and hail may occur. ...Synopsis... A vigorous mid/upper-level trough will dig southeastward across the central/northern Plains later today. In response to this system, a shortwave trough initially over the southern High Plains will eject quickly east-northeastward during the day toward the ArkLaTex. The combination of these systems will eventually result in development of a deep and progressive trough becoming established over the MS Valley by early Sunday morning. As this occurs, a surface low will develop along a cold front across the south-central Plains. This surface low will deepen and move northeastward through the period, eventually reaching Lower MI by 12Z Sunday morning. ...Eastern TX/OK into parts of the lower/mid MS Valley... Convection will likely increase in coverage and intensity from southern MO into eastern OK/TX from late morning onward, as the ejecting shortwave trough approaches the region. Moderate buoyancy and strengthening deep-layer shear will support organized convection that will spread eastward through the afternoon. Initial supercell development could pose a threat for a hail and locally damaging wind, along with some tornado potential. Increasing ascent will tend to favor eventual storm clustering and possible QLCS development with time, resulting in a continued damaging-wind threat, along with some embedded brief tornado potential. Guidance generally depicts a local buoyancy minimum across eastern AR into western TN by late afternoon, which could cause some weakening as storms move into this area. However, a notable increase in the low-level jet may support some reintensification of storms during the evening near and east of the lower MS Valley. A continued threat for damaging winds and possibly a couple of tornadoes may persist overnight near and north of the central Gulf Coast vicinity. ...Parts of the Ohio Valley/Midwest... Early-day convection across parts of the southern Great Lakes vicinity could produce locally gusty winds, through weak instability may tend to limit organized severe potential with the morning storms. Additional storms may develop during the afternoon within a favorably sheared environment, with a strongly forced line becoming possible later this evening/overnight as the surface low deepens and moves northeastward. The magnitude of the severe threat may be limited by scant instability, but strong ascent and strong deep-layer flow/shear will support some potential for damaging gusts and perhaps a brief tornado or two. ..Dean/Thornton.. 10/18/2025
