Current 00Z GFS and ECMWF ensemble means indicate robust thermal advection and amplifying anticyclonic ridging over Shanghai for April 27th. Climatological normals are understating the synoptic setup. Surface boundary layer heating from strong insolation pushes the 70% probability cone to exceed 26°C, with some outliers hitting 28°C. Market implied probability for <=25°C is mispriced. 95% YES — invalid if a significant cold front occludes or sustained precipitation develops before 06Z April 27.
