Forecaster summary - Issued 2024-09-24T00:13:49

GOES-16 high energy electron flux has varied between moderate and high levels, likely as a consequence of an increase in flux after the CME arrival on 16-17 Sep, followed by an outward expansion of the radiation belts. Flux is likely to drop out under the current and forecast CME and HSS effects, with the subsequent increased solar wind pressure likely compressing the radiation belts once again. There is potential for another increase in flux later in the period, after CME and HSS effects have subsided.

The associated 24 hour fluence reached the Active (1e8 integrated pfu) level during 22-23 Sep but has since dropped below, likely due to the recent weak CME arrival. Confidence is low during this period, but it seems most likely that fluence will remain below the Active threshold on a declining trend at first, before potentially rising on Day 4 (27 Sep). MOSWOC REFM also suggests a gradual declining trend to the fluence, however until recently this has been consistently underestimating the observed fluence reducing confidence in this model guidance.