Ultimately traced to Zhuge Liang's 《后出师表》: 凡事如是,难以逆料 - 'that's how things are; they're hard to foresee in advance'. Later rephrased 逆料 to 预料 for modern usage.
usage
A calm, neutral register - common in news, commentary, and analysis. Pairs with 结果, 后果, 走向, 变化. Softer than 莫测 (unfathomable).