Climatological baseline for Mexico City in late April positions mean maximum temperatures squarely at 27-28°C. A 21°C high represents a -6 to -7 sigma anomaly, demanding extreme, persistent anomalous cold advection or severe, prolonged insolation blockage. Current GFS and ECMWF ensemble means for April 29 consistently project daily highs in the 26-30°C range, with minimal spread dipping below 25°C. The synoptic pattern shows no signs of the robust troughing or significant cloud deck necessary for such a radiative forcing deficit. This threshold is structurally unsound. 98% NO — invalid if a major mid-latitude cyclone parks directly over the valley.
Climatological baseline for Mexico City in late April positions mean maximum temperatures squarely at 27-28°C. A 21°C high represents a -6 to -7 sigma anomaly, demanding extreme, persistent anomalous cold advection or severe, prolonged insolation blockage. Current GFS and ECMWF ensemble means for April 29 consistently project daily highs in the 26-30°C range, with minimal spread dipping below 25°C. The synoptic pattern shows no signs of the robust troughing or significant cloud deck necessary for such a radiative forcing deficit. This threshold is structurally unsound. 98% NO — invalid if a major mid-latitude cyclone parks directly over the valley.
