Forecaster summary - Issued 2022-09-04T00:24:38

The high energy (greater than 2 MeV) electron flux has become moderate, due to the recent enhancement from the fast speed stream originating from CH19/+, recharging the Van Allen belts in electron populations. A more notable enhancement is expected once the high speed stream from CH20/+ connects with Earth, leading to a more significant increase within the next 24 hours. The electron flux is expected to reach high levels, however any geomagnetic activity (following the onset of the HSS or due to CME influences) will temporarily suppress the electron counts, inevitably generating some uncertainty with regards to the timing. Flux levels are then expected to rise erratically during day 1 and day 2, before comfortably remaining above high levels during day 3 and day 4.   

The corresponding 24-hour fluence is expected to display a sharp rising trend from 04 Sept (day 1) onward, with a chance of exceeding the Active threshold from day 3 (06th) onwards. This is supported the latest Met Office REFM output, although the model is considered to slightly under-estimate the fluence levels.