SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1220 AM CDT Thu Oct 30 2025 Valid 301200Z - 311200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE ATLANTIC... ...SUMMARY... Thunderstorms with an isolated damaging wind/tornado threat may occur from coastal North Carolina into parts of the Mid Atlantic. ...Middle Atlantic... Seasonally strong upper low over eastern TN is beginning to eject northeast, partly in response to an upstream speed max digging southeast across the northern High Plains. This lead low will advance into WV by 18z before moving into upstate NY by the end of the period. Favorable high-level diffluence/large-scale ascent will encourage a surface low to be drawn north-northwest across the Middle Atlantic to a position near the MD/PA border by mid day. This track will permit higher theta-e air mass to overspread eastern VA/Delmarva into southeast PA such that buoyancy will become supportive of deep convection. Early-day shear will prove strongest across the Middle Atlantic as LLJ will be focused across eastern MD into central PA. LLJ will shift quickly north into NY by 18z along with more focused low-level warm advection. Prior to this, forecast soundings exhibit strongly sheared environment with adequate instability for thunderstorms. While the maximum SBCAPE should peak near 500-600 J/kg, a few robust updrafts are possible given the strength of the wind fields. Isolated strong/severe thunderstorms, possibly supercells, may generate damaging winds and perhaps a tornado or two. Greatest risk is between sunrise and 21z. ..Darrow/Wendt.. 10/30/2025
