Dating when NOAA PSL's NMME heatwave forecast runs went public

NOAA PSL's marine-heatwave forecast files (downloads.psl.noaa.gov/Datasets/marinehw/NMME_prob90_latest.nc and the detrended version) are overwritten every month, with no dated copies, so a look-ahead-free backtest can't read a run's release date from the file. Instead, list Wayback captures of the product page (web.archive.org/cdx/search/cdx?url=psl.noaa.gov/marine-heatwaves/&output=json&from=YYYYMM&to=YYYYMM) and read the 'Forecast initial time' text in each capture. In late 2025 the page still showed the September run on every capture through Dec 8 (the US federal shutdown ran Oct 1 to Nov 12, 2025), so the October and November 2025 runs were not public by Dec 1. Wayback captured the .nc only twice in five months, so save and hash your own dated copies each month. In the file, start_time is days since 2021-01-01, and lead 0.5 is the start month.