Climatological mean max for Sao Paulo in late April is 26°C. However, current NWM ensemble guidance from GFS and ECMWF robustly projects a significant mid-tropospheric ridge over SE Brazil by April 27th. This synoptic pattern drives potent warm air advection, with positive 500mb geopotential height anomalies pushing temperatures into a substantial thermal anomaly. Probabilistic outlooks show a >70% likelihood of exceeding 29°C, positioning 30°C as highly probable. 85% YES — invalid if the ridge axis shifts westward by >5 degrees longitude.
Climatological mean max for Sao Paulo in late April is 26°C. However, current NWM ensemble guidance from GFS and ECMWF robustly projects a significant mid-tropospheric ridge over SE Brazil by April 27th. This synoptic pattern drives potent warm air advection, with positive 500mb geopotential height anomalies pushing temperatures into a substantial thermal anomaly. Probabilistic outlooks show a >70% likelihood of exceeding 29°C, positioning 30°C as highly probable. 85% YES — invalid if the ridge axis shifts westward by >5 degrees longitude.
