SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0142 PM CST Sat Nov 15 2025 Valid 152000Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS EASTERN OHIO INTO NORTHERN WEST VIRGINIA INTO WESTERN PENNSYLVANIA... ...SUMMARY... Isolated severe gusts are possible across parts of the upper Ohio Valley late this afternoon and evening. ...20z Update... No changes are needed to the current D1 Convective Outlook. A few occasional stronger cores have been noted near the warm front across western New York into southern Ontario. Overall, limited moisture and poor thermodynamics have limited the severe threat. Further south across the upper Ohio Valley, additional convective development is expected along the front later this afternoon. Though mid-level cloud cover has prevailed, dew points in the 50s are observed across Ohio into northern West Virginia and Pennsylvania. Here a narrow region of weak instability overlapping with increasing forcing for ascent will support potential for locally damaging gusts. ..Thornton.. 11/15/2025 .PREV DISCUSSION... /ISSUED 1030 AM CST Sat Nov 15 2025/ ...Upper Ohio Valley... Water-vapor imagery late this morning shows a mid-level trough over the Upper Great Lakes. This mid-level trough will quickly move east into the Lower Great Lakes vicinity by early evening with an attendant increase in large-scale forcing for ascent expected to spread across the Upper OH Valley and Lower Great Lakes regions. Although primary cyclone development will occur from eastern Lake Superior eastward to the VT/Quebec region, a cold front will push southeastward across the Great Lakes into the central Appalachians during the period. Despite low-level theta-e advection into the region from the lower OH Valley, the overall magnitude of destabilization will be limited in part due to considerable cloud cover thwarting greater heating. Models show surface dewpoints rising into the upper 50s beneath a capping inversion by late afternoon. Weak instability and the aforementioned forcing will aid in the eventual development of isolated to scattered thunderstorms probably in the form of one primary band of convection towards early evening. Strong to locally damaging wind gusts are the primary concern, with convection expected to weaken with eastward extent into central PA this evening due to meager instability with the loss of daytime heating. ...Southern California/Southwest... A potent mid-level speed max translating through the base of a trough west of southern CA/Baja CA will move into the Mojave Desert later today. Pockets of weak instability will likely develop today and favor isolated bouts of deeper convection across southern CA into the lower CO River Valley. Despite strengthening mid-level flow fields, muted lapse rates will likely limit storm intensity and the propensity for strong/locally damaging gusts.
