SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0100 PM CST Thu Nov 13 2025 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE SATURDAY AFTERNOON AND EVENING ACROSS PARTS OF EASTERN OHIO...WESTERN PENNSYLVANIA AND NORTHERN WEST VIRGINIA... ...SUMMARY... Showers and a few thunderstorms may be accompanied by strong wind gusts across parts of the upper Ohio Valley late Saturday afternoon and evening. ...Discussion... Saturday into Saturday night, it appears that the more progressive flow emanating from the northern mid-latitude Pacific will begin to impinge on the blocking regime now evolving across parts of eastern North America into the Atlantic. While an initially prominent cyclone on the leading edge of this regime is forecast to undergo considerable deformation and weakening, models continue to indicate that a notable perturbation emerging from it will dig across the upper through lower Great Lakes, accompanied by secondary surface cyclogenesis. Upstream, the westerlies may undergo notable amplification, including digging mid/upper troughing offshore of the British Columbia and northern Pacific coast and building ridging across and east of the Canadian/northern U.S. Rockies. As this occurs, an initially cut-off low offshore of the southern California/northern Baja coast is forecast to accelerate into the Southwest late Saturday through Saturday night. ...Upper Ohio Valley... Within the warm sector of the developing surface low, NAM forecast soundings indicate that modest low-level moisture return may become supportive of the development of thermodynamic profiles characterized by weak conditional and convective instability in the lowest 5-6 km AGL. It appears that this environment could become at least marginally conducive to boundary-layer based convection capable of producing lightning by late Saturday afternoon, mainly near the southern periphery of the colder mid-level air, across parts of northeastern Ohio into the western slopes of the Allegheny Mountains. In the presence of strengthening lower/mid-tropospheric wind fields (including 40-50+ kt west-northwesterly mean flow in the lowest 6 km AGL), the development of a relatively compact band of stronger showers and thunderstorms appears possible. This activity, perhaps aided by latent cooling in downdrafts associated with melting small hail, may contribute to the downward transfer of stronger winds to the surface, before convection weakens while crossing the Allegheny Mountains Saturday evening. ...Southwest... Models suggest that a mid-level cold core, characterized by 500 mb temperatures as cold as near or just below -20 C, will finally shift inland late Saturday through Saturday night. These temperatures appear on the relatively warm side compared to cool season environments typically conducive to low-topped convection capable of producing lighting across and inland of Pacific coastal areas. However, it is possible that low-level moisture return emanating from the lower-latitude eastern Pacific and Gulf of California may compensate. Otherwise, it might not be out of the question that preceding elevated moisture return contributes to layers of weak conditional instability minimally supportive of convection capable of producing lightning across parts of the Mojave Desert/lower Colorado Valley vicinity. ..Kerr.. 11/13/2025
