Forecaster summary - Issued 2021-09-12T00:00:46

The high energy electron flux, as measured by GOES-16, has been just reaching moderate levels at the diurnal maximum over the last 24 hours. With enhanced geomagnetic activity expected on Day 1, the electron flux is unlikely to rise significantly at first. However a more sustained increase in counts is then possible from Day 2 as the high speed stream from coronal hole 99 becomes established, perhaps reaching high levels during the diurnal maximum.

The corresponding 24-hour electron fluence is expected to remain below the Active (1e8 integrated pfu) threshold, albeit with a rising trend on Days 2 to 4 (13th to 15th). A similar pattern was observed on the last rotation although the electron count never reached high levels. This is also confirmed by the latest REFM output and the Recurrence-Persistence Electron forecast, both considered to provide good guidance.