Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1230 AM CDT Fri Mar 20 2026 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER OHIO VALLEY REGION... ...SUMMARY... Strong to locally severe thunderstorms are possible across parts of the Upper Ohio Valley, mainly late this afternoon into the evening. ...Upper Ohio Valley... Dominant upper ridge will hold across the southwestern parts of the CONUS through the day1 period, but this feature will influence most of the western US by forcing stronger westerlies to near the international border/Great Lakes region. Latest model guidance suggests a weak shortwave trough will top the ridge and dig southeast across the Great Lakes into the upper OH Valley by 21/00z. As this occurs weak midlevel height falls will be noted across eastern OH/PA as a surface cold front settles across western NY-northern OH-central IN by late afternoon. Early this morning, boundary-layer moisture is quite dry across much of the OH Valley with only upper 30s/lower 40s surface dew points observed. Deepening westerly flow suggests low-level moisture across southeast MO/northern AR will advect toward the upper OH Valley, possibly arriving prior to the frontal passage. Even so, dew points within this source region are only in the mid 40s to lower 50s. Forecast soundings for mid afternoon suggest modest boundary-layer heating such that 0-3km lapse rates should be on the order of 7 C/km with MUCAPE around 500-700 J/kg. Current thinking is scattered convection will develop along/ahead of the cold front by late afternoon, then spread southeast before weakening with loss of daytime heating. Strong deep-layer shear favors organized updrafts and the greatest risk should be gusty winds with marginally severe hail. ..Darrow/Chalmers.. 03/20/2026Read more