Forecaster summary - Issued 2021-09-02T00:14:07

The high energy electron flux (greater than 2 MeV) as measured by GOES-16 at GEO has reached high levels over the past few days. It is likely that there will be a declining trend over the next 24 hours or so, but still with flux levels rising to high at the diurnal maximum. There are uncertainties thereafter, with temporary electron flux suppression possible, associated with increased geomagnetic activity from a possible CME arrival on Day 1 (2nd Sep). If we see this CME arrival, electron counts would be expected to rise to moderate to high levels again later in the period (Days 2 to 4).

The associated 24 hour fluence is currently justabove the Active threshold but with a decreasing trend and is likely to ease below the Active threshold during Day 1 (2nd). Any re-enhancement is low confidence at this stage and heavily dependent on any increased electron counts in the wake of any CME activity. REFM guidance will be of limited use during this forecast period, especially beyond T+24 when it becomes primarily persistence based.