Forecaster summary - Issued 2021-09-28T00:03:12

The high energy electron flux (greater than 2MeV) has been at background or moderate levels. The potential geomagnetic enhancements would initially limit any increasing flux, due to the compression of the radiation belts from fast wind or CME effects. If there is a CME or high speed stream arrival, then the flux would be expected to start increasing from Day 2 (29 September), perhaps reaching High levels towards the end of the four day period.

24 hour electron fluence values are forecast to remain below the Active threshold to start the period. Any significant increase would be dependent on further CME influence or high speed stream onset on Day 1. If these don't occur, then fluence is likely to remain below Active as per REFM (which doesn't take into account CME arrivals). However, if they do occur then fluence increase is likely, perhaps reaching Active levels later in the period.