Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1200 AM CST Wed Feb 18 2026 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS MUCH OF CENTRAL AND SOUTHERN ILLINOIS AND INDIANA...PARTS OF WESTERN AND NORTHERN KENTUCKY AND SOUTHWESTERN OHIO... ...SUMMARY... Severe thunderstorms, with potential to produce a few tornadoes and damaging wind gusts, are possible across parts of the middle Mississippi into lower Ohio Valleys Thursday afternoon into early evening. ...Discussion... There remains notable spread evident in the latest model output concerning a number of synoptic and sub-synoptic developments within the evolving pattern across North America through this period. In general, though, guidance continues to indicate that larger-scale mid-level troughing will slowly begin to shift inland of the Pacific coast Thursday through Thursday night, while being maintained downstream across the Rockies, Great Plains and Mississippi Valley, and slowly developing toward the lower Great Lakes and Appalachians vicinity. As this occurs, the center of a mid-level subtropical ridge is likely to shift from the southern Gulf Basin into the Bahamas/Caribbean, with its northern periphery maintaining an influence across parts of the Southeast. A couple of initially lower amplitude short wave perturbations, within a seasonably strong belt of flow emerging from the Southwest, may be in the process of progressing into and across the central Great Plains toward the middle Mississippi and lower Ohio Valleys at the outset of the period. The lead perturbation, probably accompanied by a 500 mb speed maximum of 90-100+ kts, is forecast to continue into and across the lower Ohio Valley during the day, as the trailing one pivots northeastward and perhaps intensifies across the middle Mississippi Valley toward southern Great Lakes region later Thursday through Thursday night. Associated with these developments, a sub-1000 mb surface cyclone is forecast to migrate across and northeast of the lower Missouri Valley during the day, perhaps slowly deepening, before continuing toward the upper Great Lakes accompanied by more substantive deepening Thursday night. ...Middle Mississippi/Lower Ohio Valley... It appears that warming aloft, associated with subsidence to the south of the trailing mid/upper jet, will tend to eventually overspread the better (but still relatively modest) low-level moisture return to the evolving warm sector across the lower Ohio Valley. However, to still differing degrees, the latest runs of the various model output indicate a window of opportunity for strong to severe thunderstorm development, perhaps beginning by early afternoon, aided by daytime heating and subtle mid-level cooling/forcing for ascent accompanying the lead jet streak. The consensus of latest guidance, supported by the High Resolution Ensemble and related machine learning output, suggests that this may initiate across portions of Illinois, near or to the north and east of the Greater St. Louis area, with strongest activity tending to develop eastward and perhaps peak while spreading across east central and portions of southeastern Illinois through portions of central and southern Indiana by early Thursday evening. Forecast soundings across this corridor remain generally characterized by at least modest convective instability, and CAPE on the order of 500-750+ J/kg, in the presence of strong deep-layer shear. Sizable clockwise-curved low-level hodographs, beneath 40-50+ kt south to southwest flow in the 850-700 mb layer, may promote supercells capable of producing severe hail and a few tornadoes, and activity may eventually grow upscale enough to support increasing potential for damaging wind gusts before convection wanes late Thursday evening. ..Kerr.. 02/18/2026Read more
