Forecaster summary - Issued 2025-04-23T00:29:29

High energy electron flux (greater than 2MeV) has been at mostly moderate levels during the last 24 hours. The current HSS is likely to be driving an increase in electron flux below GEO, given the strong wind speeds and recent geomagnetic activity. As the HSS eases a little, and the Van Allen belts relax back towards GEO, diurnally high flux levels are possible by around Days 2 onwards (24 Apr). However, the timing of the increase is low confidence given that the coronal hole is a large feature and wind speeds are rather uncertain during this period. This is also complicated by potential CME arrival on day 2 (24 Apr).

The associated 24 hour fluence is currently below Active (1e8 integrated pfu) and has been on a slow and steady rise. A further in fluence is possible later in the period, with a chance of reaching above the Active (1e8 integrated pfu) threshold by day 2 onwards. MOSWOC REFM is forecasting a sharp rise, up to the Very Active level, but this is considered significantly overdone (this is not uncommon with REFM in the early stages of a response to a HSS).