Forecaster summary - Issued 2026-04-10T00:18:26

High energy (>2 MeV) electron flux as observed by GOES19 has been mostly High over the last 24 hours. The arrival of the HSS from CH38/+ into Day 1 (10 Apr) looks likely to at least temporarily reduce flux to Moderate or perhaps background levels for a time. Increasing solar wind pressure perhaps already giving some compression of the radiation belts with flux values seeing a reduction in recent hours. Into Day 1 (10 Apr) potential geomagnetic activity also likely acting to redistribute electrons into Days 1 and 2 (10-11 Apr). Electron flux then expected to generally rise once again into the period, with further High or Very High electron flux levels likely returning as HSS influence eases Days 3 and 4 (12-13 Apr).

The 24 hour electron fluence is expected to generally remain above the Active (1e8 integrated pfu) threshold throughout this period, possibly reducing temporarily into Day 2 (11 Apr) following HSS influence, before rising again later Day 3 into Day 4 (11-12 Apr) as flux levels are expected to increase once again. MOSWOC REFM output has been significantly underestimating fluence values and is not supported, although the general trend signalled via persistence is considered reasonable guidance.