Forecaster summary - Issued 2025-05-31T00:12:01

Electron flux increased to high levels through the UTC day, peak 4880pfu at 30/1700 UTC, due to the ongoing fast wind enhancement associated with CH52/-. A further rise in electron flux at GEO is likely over the next few days, at least at the diurnal peaks, and potentially staying mostly above. However, there is also the potential for a glancing CME later Day 2 into Days 3 (01-02 Jun), which could knock the electron flux back down again, but this is low confidence.

Electron fluence has been on a rising trend and just breached the Active threshold (1e8 integrated flux) at 30/2100 UTC. The upward trend is expected to continue over the next few days, with fluence levels probably remaining above the Active threshold. However, any CME influence through Days 2 and 3 could cause the fluence to drop again. The MOSWOC REFM model is considered to be giving good guidance for the overall rising trend, but it is likely to be significantly overestimating the fluence values, which is a common feature of this model in the early stages of a response to a high speed stream, and a similar profile to recurrence is considered more likely..