Forecaster summary - Issued 2018-05-27T00:13:30

The high energy electron flux is expected to see a gradually rising trend during the period, and may reach high levels (greater than 1000pfu) at peaks of the diurnal cycle by Days 3 and 4 (30 and 31 May). Electron counts may see temporary reductions associated with any isolated Active intervals of geomagnetic activity on Days 2 and 3 (28 and 29 May), but the general overall trend will most likely be upwards.

The corresponding 24-hour electron fluence is expected to show a gradually rising trend in response, but is not expected to exceed the Active threshold (1e8 integrated pfu) within the forecast period.

The REFM forecast out to T+24 of steady or slowly rising fluence is considered broadly correct, however the jumps predicted at T+24 and T+48 are not expected, with fluence most likely to continue showing a slow rise, but remaining below the Active threshold (1e8 integrated pfu). These unrealistic model forecasts of large jumps are due to isolated spurious solar wind readings observed in recent days.