Envision Energy said its Tianji model ranked first in the European Centre for Medium-Range Weather Forecasts (ECMWF) contest for forecasts 19 to 25 days ahead, a horizon relevant to energy planning.
ECMWF’s team profile lists Envision Energy and members affiliated with Tsinghua University under Arcana. Envision said Oct. 30 that Tianji ranked first among nearly 20 teams and led the evaluated results for temperature, pressure and precipitation.
ECMWF’s ASO 2026 results table places Arcana first in the variable-averaged ranking for the 19-to-25-day window. Its top entry, ArcanaSphericalBeta, has a global Ranked Probability Skill Score (RPSS) of 0.236. ECMWF says an RPSS of 0.0 corresponds to a forecast based on climatology.
The results page says its data draw on a single forecast run initialized Aug. 13 and gives Sept. 19 as its latest update. The table reports an aggregate result for that run; it does not show an Oct. 30 standing or separate first-place results for each metric.
The contest collects weekly probabilistic forecasts for near-surface temperature, mean sea level pressure and accumulated precipitation. Teams forecast two ranges: days 19 to 25 and days 26 to 32. ECMWF says better forecasts at these lead times may help energy, agriculture and disaster risk reduction. Envision says it has applied Tianji to energy forecasting.
“Subseasonal forecasting — two weeks to two months out — is one of the hardest challenges in meteorology,” said Robert Zheng, head of Envision’s Tianji Weather Foundation Model.
Under ECMWF’s terms, participants receive no monetary prize or compensation and cover their own participation expenses. The current SON 2026 bridge period is scheduled to run through Nov. 5, and the next competition period begins Nov. 12.
