Forecaster summary - Issued 2021-06-18T00:04:55

Due to the influence of the ongoing, but gradually declining, high speed stream from CH68 the high energy electron flux (greater than 2MeV) is expected to remain above the High threshold (1000 pfu) for much of the forecast period, perhaps decreasing to Moderate levels through day 4 (21st). The 24-hour integrated fluence threshold is therefore expected to remain above the Active threshold (1e8 integrated pfu) through most of the period.

The Met Office REFM model concurs with fluence levels remaining above the Active (1e8 integrated pfu) threshold today, but then shows a gradually declining trend from day 2 (19th), although with fluence levels still slightly above the Active threshold at times through days 2 and 3 (19th and 20th). The model is considered to be offering reasonable guidance, although a slightly higher and more level trend is preferred.