Forecaster summary - Issued 2023-09-13T00:16:09

High energy (greater than 2 MeV) electron flux observed by GOES-16 may to increase through Day 1 (13 Sep), rising to Moderate, perhaps High at diurnal peak, with the recent unexpected CME likely to have increased the flux through the Van Allen belts. However this rise is low confidence, with the potential for any coronal hole fast wind arrival to disrupt the belts and lead to a drop out in observed flux which may only slowly recover later in the period.

The associated 24-hour fluence will most likely remain below the Active (1e8 integrated pfu) threshold. Confidence for this is somewhat reduced however, with a slight chance of rising above during Day 1 (13 Sep) largely depending on the length of time until any drop out occurs from expected coronal hole high speed stream influence. MOSWOC REFM is considered to be giving generally good guidance.