Forecaster summary - Issued 2021-08-17T12:01:47

The high energy electron flux, as measured by GOES-16, has been reaching moderate levels at the diurnal maximum over the last 24 hours. The solar wind speed is expected to continue declining back to slow-ambient levels as it transitions into typical slow wind conditions over the next 24 hours. As such the electron flux is expected to continue reaching moderate levels over the next few days, but is unlikely to rise significantly further as the driving wind speeds are declining.

Corresponding electron fluence is currently well below the Active (1e8 integrated pfu) threshold on a steadily rising trend. As flux levels are not anticipated to rise much further, this trend is expected to level off over the next 24-48 hours, likely remaining below the Active threshold. REFM does indicate a rising trend but below Active which is considered reasonable guidance. 

Later on Day 4 (20 Aug), we may see the arrival of a weak high speed stream from CH90/-. This is likely to suppress electron flux on Day 4, causing a dip in the fluence level, before any charging response may occur which is likely to be beyond the end of this four day period.