Sao Paulo's May climatological mean maximum is 23.5°C, making 27°C a significant positive anomaly. D+10 GFS and ECMWF ensemble means are consistently forecasting a pronounced positive 500hPa geopotential height anomaly over southeastern Brazil for May 5, indicative of a dominant upper-level thermal ridge. This synoptic pattern will facilitate robust northerly warm air advection at 850hPa, pushing temperatures well above seasonal norms. Forecasted 850hPa temperatures exceed 18°C across the region, translating to surface highs easily clearing 27°C, especially with low cloud cover probabilities. The absence of a significant South Atlantic Anticyclone eastward migration prevents cool maritime air intrusion, while a southerly displaced polar jet stream minimizes cold front influence. Sentiment: Local atmospheric science models are aligning on this unseasonal warmth. This is a clear exceedance. 90% YES — invalid if a late-season cold front accelerates faster than currently modeled.
Sao Paulo's May climatological mean maximum is 23.5°C, making 27°C a significant positive anomaly. D+10 GFS and ECMWF ensemble means are consistently forecasting a pronounced positive 500hPa geopotential height anomaly over southeastern Brazil for May 5, indicative of a dominant upper-level thermal ridge. This synoptic pattern will facilitate robust northerly warm air advection at 850hPa, pushing temperatures well above seasonal norms. Forecasted 850hPa temperatures exceed 18°C across the region, translating to surface highs easily clearing 27°C, especially with low cloud cover probabilities. The absence of a significant South Atlantic Anticyclone eastward migration prevents cool maritime air intrusion, while a southerly displaced polar jet stream minimizes cold front influence. Sentiment: Local atmospheric science models are aligning on this unseasonal warmth. This is a clear exceedance. 90% YES — invalid if a late-season cold front accelerates faster than currently modeled.
