Forecaster summary - Issued 2021-09-11T00:29:19

Enhanced geomagnetic activity on day 1 (11 September) is likely to restrict the high energy electron flux (greater than 2MeV) to generally background levels. Diurnal variations are then possible through days 2 and 3, but with a chance of further geomagnetic enhancements restricting any increases. A more sustained increase in counts in then possible from day 3 (13 September) as the high speed stream from coronal hole 99 becomes established, but high levels are considered unlikely.

Electron fluence values are expected to remain below the active (1e8 integrated pfu) threshold through much of the period, perhaps with a rising trend by day 4.