Forecaster summary - Issued 2026-04-09T00:21:59

High energy (>2 MeV) electron flux as observed by GOES19 has been mostly High over the last 24 hours, with only a brief early period at moderate levels. Recent HSS influence appearing to have caused significant charging within the outer radiation belt. Electron flux levels likely to only increase further initially into Day 1 (09 Apr), but the arrival of the HSS from CH38/+ late on Day 2 (09 Apr) or into Day 3 (10 Apr) looks likely to at least temporarily reduce flux to Moderate or perhaps Background levels. Solar wind pressure and potential geomagnetic activity acting to redistribute electrons and compress the radiation belts. Electron flux then expected to generally rise once again into the second half of the period, with further High or Very High electron flux levels potentially returning toward the end of the period as HSS influence eases.

The 24 hour electron fluence is now expected to remain above the Active (1e8 integrated pfu) threshold throughout this period, possible briefly reducing after the HSS arrival into Day 2 (10 Apr). The below Active forecast Day 1 (09 Apr) onwards currently shown within MOSWOC REFM is not supported, though the rising trend signalled later in the period is considered reasonable guidance.