Forecaster summary - Issued 2021-04-29T00:01:23

Electron flux levels have been mostly Moderate, but just about reached the High (1000 pfu) alert threshold at the diurnal maximum. This has been driven by the recent enhanced solar wind speeds. However solar wind speeds are now back down to ambient levels, and are expected to remain that way through most of Days 1 and 2 (29 and 30 Apr). As such flux levels should start to level off or drop, perhaps just reaching High levels at the diurnal maxima through the next 2 days. Thereafter an enhancement in the solar wind speed is possible on Day 3 (01 May) due to CH50/+, although confidence is low in the level of wind speed likely to be reached. This may cause a temporary drop in electron flux on Day 3, due to the possibility of compression of the radiation belts, before a rebound is likely on Day 4 (02 May) if wind speeds do increase.

The associated fluence has been on a rising trend through the last 24 hours, although below the Active (1e8 integrated pfu) threshold. As flux levels are expected to level off or drop over the next couple of days, fluence is expected to stay below the Active threshold through Days 1 to 3. A rise is then possible on Day 4, although this is currently low confidence.