Forecaster summary - Issued 2025-05-18T00:09:03

High energy electron flux appears to be in a steady state, showing very low values since the arrival of a CME's glancing blow earlier on 17 May. This has since been followed by the early connection to the HSS originating from CH48/+, which has seen solar winds rising significantly. This is likely to suppress the electron flux during day 1, at leas temporarily, and maintain it at Background levels. However, the Van Allen radiation belts should soon replenish and an increase in electron flux is likely to manifest itself at GEO towards the end of the guidance period, with the likelihood of breaching diurnally high flux levels by around Day 4 (21 May). A similar rise was observed during the last rotation but the High level was never attained.

MOSWOC REFM is currently accepted as giving reasonable guidance. It is showing an increase in the associated 24-hour fluence leading to a breach of the Active (1e8 integrated flux) threshold on Day 3 or/and Day 4. The risk is considered moderate at best, which is reflected by the modest probabilities.