ECMWF and GFS ensemble means firmly indicate minimum temperatures converging around 9-10°C for Tokyo on May 10. A robust upper-level trough will drive persistent northerly cold air advection across Honshu, immediately followed by clear post-frontal conditions conducive to enhanced nocturnal radiational cooling within the urban boundary layer. The anomalous low-level thermal gradient strongly favors sub-11°C readings. This setup presents high confidence for colder-than-average lows. 95% YES — invalid if the synoptic pattern shifts to a maritime tropical flow.
ECMWF and GFS ensemble means firmly indicate minimum temperatures converging around 9-10°C for Tokyo on May 10. A robust upper-level trough will drive persistent northerly cold air advection across Honshu, immediately followed by clear post-frontal conditions conducive to enhanced nocturnal radiational cooling within the urban boundary layer. The anomalous low-level thermal gradient strongly favors sub-11°C readings. This setup presents high confidence for colder-than-average lows. 95% YES — invalid if the synoptic pattern shifts to a maritime tropical flow.
