Forecaster summary - Issued 2024-09-21T00:23:37

High energy flux, as observed by GOES-16 at GEO has shown an increase through 19 and 20 Sep with rising to High at diurnal maximum between approximately 20/1430-2000 UTC. This is due to the charging of lower orbital levels, from the CME arrival overnight on 16-17 Sep, which, as solar winds have subsequently eased, have expanded outward. With no further notable solar wind enhancements during the period, forecast flux is likely to persist at Moderate to High at GEO, perhaps becoming persistently High from later Day 1 (21 Sep). Confidence does fall later in the period however, due to the potential for any weak solar wind enhancement from the arrival of fast winds from CH71/+ which could potentially cause a drop out in observed flux later on Day 2-3 (22-23 Sep).

The associated 24 hour fluence is expected to continue its rising trend, likely rising to around, or just above the Active level (1e8 total pfu) later Day 1 or into Day 2 (21-22 Sep). This rising trend is indicated by REFM, but is currently considered underestimated. The confidence falls later in the period due to uncertainty in any HSS influence.