Forecaster summary - Issued 2026-04-22T00:28:24

GOES19 High energy (>2 MeV) electron flux increased has increased from Moderate to High as the fast winds of CH42/- and any associated geomagnetic activity decline. While further periods of Moderate flux are possible, especially during the minimum of the diurnal cycle, this increasing trend is likely to continue into day 2 (23 Apr), with mainly High flux persisting beyond this. With the recently observed CMEs expected to miss Earth, the next solar wind enhancement is likely to from the fast winds of CH46/+, which has recently moved into the western disc. This is most likely to occur on day 4 (25 Apr), and will likely lead to flux dropping out to be Moderate to Background.

The associated 24 hr fluence is expected to rise above the Active level on day 1 (22 Apr) and then persist above this level through the period, albeit with declining confidence. However, the onset of the fast winds of CH46/+ has the potential to reduce the fluence below Active later on day 4 (25 Apr).  Fluence has now risen to be similar MOSWOC REFM expectations, which had been over-estimating values, and this model is expected to provide reasonable guidance in the short-term. However, this is also likely to reduce levels too quickly later in the period, with fluence most likely to remain Active.