Forecaster summary - Issued 2022-09-23T00:29:50

High energy electron flux (greater than 2 MeV) as observed by GOES16, is currently Background to Moderate. The arrival of the fast wind of CH25/+ today is expected to enhance electron populations at Earth, with High flux levels perhaps developing during days 3 and 4 (25th and 26th) once initial geomagnetic activity subsides - if the 21st Sept CME does not arrive during day 3 and maintain enhanced geomagnetic activity and so suppressing the high energy electron count.

The associated 24-hour fluence is expected to stay below the Active (1e8 integrated pfu) threshold through most the period, but possibly rising above by the end of day 4 (26th). The REFM is giving a good guide, keeping the fluence below the Active threshold during the first 3 days. However, as the HSS from CH25 is likely to be stronger than persistence suggests, so the REFM will struggle to show this. Therefore an increasing trend in the fluence is preferred.