Forecaster summary - Issued 2021-05-27T00:01:57

The high energy (greater than 2 MeV) electron flux as observed at GOES-16 has been varying diurnally between moderate and high levels, but has dropped out to near background levels with the arrival of the anticipated CME earlier today. Further CMEs are likely to arrive over the next 12-24 hours, likely keeping electron levels suppressed. Once the CMEs have passed and geomagnetic activity subsides, observed flux is expected to climb towards the Alert level, with a chance of exceeding the threshold by Days 3 and 4 (29 and 30 May). 

The associated high energy fluence is forecast to remain below the Active threshold at first, but rising in response to any elevated flux observed post-CME clearance on Days 3 and 4. This will bring a chance of Active fluence by the end of the period. The REFM 3-day forecast and the 27-day recurrence do not suggest a rise above the threshold, however neither has information about the CME arrivals and the increase in wind speed that this has brought. The recurrence-persistence model also doesn't offer useful guidance at this time as conditions are very different from the previous rotation.