Forecaster summary - Issued 2025-09-22T00:15:41

GOES19 High energy (>2MeV) electron flux has been predominately High since 16 September, with a roughly stable peak amplitude on each day since the previous CME and coronal hole combined enhancement. 24-hour electron fluence is now very gradually ebbing away at GEO in the slow regime that has followed, such that even relatively minor enhanced solar wind pressure on the Van Allen belts is likely to spell the end of Active fluence at GEO for a time. The main uncertainty is the strength of any rebound later in the coming UTC working week, with the relevant period falling outside MOSWOC REFM's 72-hour window, and in any case changes to the responsible coronal hole may make this less reflective of forecast conditions even when in range.

On balance, current Expected Active fluence should soon fall within the UTC day, with only a Slight Chance of survival in the absence of any fast wind. After a nadir midweek, there is an increased Slight Chance of a recovery to end the four-day period.