FA-71218 / Weather index computation / Member archive

Antecedent precipitation index: multi-day gap decay · case 03

After a week without reports the index has barely decayed.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

obs are [day, precip_mm] in any order; process in ascending day order (stable for equal days). Between observations API decays by k^(day gap); several reports on the same day accumulate without decay; negative precipitation is a sensor glitch treated as 0. Return API after each observation, rounded to 0.01.

Why this case matters

Flash-flood guidance and soil wetness models use API as a moisture state.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
basin 7	`[2.0, 6.8, 8.12, 9.31]`	`[2.0, 6.8, 7.51, 8.76]`	Failed

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