Forecaster summary - Issued 2023-05-30T00:08:27

High energy electron flux (greater than 2MeV) has been at Background to Moderate levels. Through the period it is increasingly likely to return to High levels during the diurnal maximum, in the absence of any modifying factors, particularly later in the forecast. The most likely source of any geomagnetic activity is from a CME on Days 2-3 (31 May -01 Jun), although this is expected to largely pass below the Earth, resulting in limited geomagnetic activity. There is a chance that a coronal hole HSS may connect at Earth on Day 3 or 4 (01-02 June) which may act to suppress the observed flux levels. 

There is a chance that associated 24 hour fluence may recover to above Active (1e8 integrated pfu) by Day 2 (31 May). However, there is low confidence in the forecast, with REFM showing a large spread in possible fluence values. The increase in probabilities later in the forecast reflects the uncertainty with geomagnetic activity and the charging and relaxing of electron belts during the period.