Forecaster summary - Issued 2025-07-21T00:23:57

GOES-19 high-energy (>2 MeV) electron flux has persisted at High, as a result of recent fast wind enhancements, which saw solar winds exceeding 700km/s at times during the previous week. As solar winds have eased, the electron flux has continue to rise each day, with an extended period of over 10000 pfu observed on 20 Jul. Similar, perhaps slightly higher values are possible on day 1-2 (21-22 Jul), before any subsequent drop out becomes likely as a consequence of the fast wind onset from CH66. This is expected either late day 2 or day 3 (22-23 Jul), alongside the very slight chance of a CME glance at the same time. The extent of this drop-out, along with any subsequent re-enhancement as solar wind pressure eases later day 3 or more likely day 4 (23-24 Jul), is low confidence, however there is a chance of High electron flux returning by the end of the period.

The associated 24 hour electron fluence is expected to persist above the Active level until day 3 (22 Jul), although a declining trend is likely days 2-3 (22-23 Jul). Given the recent trend and the recent period of extended flux above 10000 pfu, there is a slight chance of reaching the Very High flux level, mainly days 1-2 (21-22 Jul). This is not supported by either REFM or recurrence, however this has been underestimating the observed fluence. Any reduction in flux days 2-3 (22-23 Jul) then brings a likelihood of fluence falling below the Active level,  perhaps later day 3 or more likely day 4 (23-24 Jul). However.. a subsequent recovery with fluence rising back above this level is possible by the end of the period.