Forecaster summary - Issued 2026-03-24T00:40:55

GOES19 high‑energy (>2 MeV) electron flux has increased to mainly High levels with a peak of 8290pfu at 23/1900UTC. While the impact of any glancing CME arrival on day 2 (25 March) may significantly reduce the electron count at GEO in the outer Van Allen belt, there is a chance that levels with remain High for much of the period. 

Exceedance of Active 24-hour integrated electron fluence is Likely to continue for much of the period with a slight chance of Very Active levels, with any survival at this level dependent on the glancing blow CME due early day 2 (25 March) - this CME originating from the south-eastern filament CME of 22 March. This CME renders the four-day forecast low confidence from day 2 (25 March), as Active fluence would be maintained should the CME miss. MOSWOC REFM is felt to offer good guidance in advance of this CME's possible influence, with exceedance of 1e8 integrated pfu Likely to endure. This should play out on a similar trajectory to that shown in modelling at first, however REFM cannot be followed with confidence from day 2 (25 March) owing to the possibility of a a (by this time) transient-dominated regime.