Forecaster summary - Issued 2026-05-17T00:18:55

GOES19 >2MeV electron flux was at Background to Moderate levels for most of the day, but became High for a period around 16/1740 UTC. It will likely increase through Day 1  (17 May) as the solar winds ease, with an increasing chance of reaching High levels on the diurnal peaks.

The associated 24-hour fluence has started to rise in response to the High electron flux and now seems to be following the MOSWOC REFM forecast. The increasing trend is likely to continue with solar winds reducing, and so there are indications that the fluence could reach Active on Day 1 (17 May). The MOSWOC REFM is considered good guidance, but the peak fluence values may be too high with a slight chance of reaching Very Active. There is uncertainty with regards how long the 24-hour fluence will stay Active, but this could start to come down by the end of the period.