Forecaster summary - Issued 2021-07-28T00:17:32

The high energy electron flux (greater than 2MeV) is expected to be at mainly background to moderate levels at first, with the arrival of the high speed stream from CH78 and CH79 temporarily suppressing electron flux due to compression of the radiation belts. With solar wind speeds of around 500-550 km/s expected, we would expect to see an increase in electron flux from Day 2 (29 July) onwards as the radiation belts start to rebound. However, despite similar wind speeds on the previous rotation, flux levels remained mainly at background levels during the whole period. A cautious approach is therefore advocated, with a rise in electron levels possible but currently low confidence. 

Electron flux is therefore expected to be at background to moderate levels through Day 1 (28 July), potentially increasing from Day 2 with peaks at High levels possible during the diurnal maxima on Days 3 and 4 (30-31 July).   

The associated 24 hour electron fluence may well rise accordingly through this period, but will most likely stay below the Active threshold. However there is a chance of rising above on Days 3 and 4. REFM is currently forecasting a decline in electron fluence by Days 2 and 3, but this is thought to be unlikely at the present time.