Forecaster summary - Issued 2026-03-18T00:31:58

GOES‑19 high‑energy (>2 MeV) electron flux is expected to be at Moderate levels initially, with a likelihood of reaching a diurnal High peak on Day 1 (18 Mar). However, confidence lowers from Day 2 (19 Mar) due to the anticipated arrival of the 16 Mar CME, which may suppress electrons at GEO. Further weak CMEs are likely to arrive Days 3 and 4 (20-21 Mar) which should keep electrons suppressed.

The associated 24hr electron fluence is expected to remain below the Active threshold (1e8 integrated flux) initially, but with a likely rising trend through Day 1 (18 Mar), with an increasing likelihood of breaching the Active threshold, although current observations are slightly below recurrence, with a flat trend. Lower confidence from Day 2 (19 Mar) due to likely CME arrivals. MOSWOC REFM forecast and recurrence both indicating fluence levels above the Active threshold on Day 1 (18 Mar), and this is considered generally good guidance, but with lower confidence from Day 2 (19 Mar) due to likely CME arrival.