Forecaster summary - Issued 2026-05-20T00:10:34

GOES-19 >2 MeV electron flux has remained predominantly at High levels over the past 24 hours, reaching a peak of 3610 pfu at 19/0400 UTC. However, the early CME arrival on 19 May appears to have significantly compressed the Van Allen belts, leading to a rapid depletion of energetic electron fluxes. Electron flux levels are now declining back toward moderate levels. While some recovery remains possible, confidence is low given that a second CME is expected to arrive at Earth on Day 1 (20 May). Consequently, electron fluxes may remain suppressed at low to moderate levels for an extended period.

The associated 24-hour fluence is currently Active but on a declining trend and likely to continue given the recent CME arrival. The latest REFM output is unlikely to provide reliable guidance, as it does not account for the potential effects of glancing CME impacts and should therefore be treated with caution. Overall, fluence levels are expected to decline, though the rate of decrease and how close values may approach the Active threshold (1×10⁸ pfu) remain highly uncertain and subject to low confidence.