Forecaster summary - Issued 2025-12-29T00:11:14

The diurnal oscillation in electron flux has remained above the high threshold over the past few days, and there are no likely mechanisms to reduce electron flux at GEO Days 1-2 (29-30 Dec) as geomagnetism from the current fast wind wanes. Fast winds from CH10/- may connect with Earth on Day 3 (31 Dec), which would likely compress the electron belts and result in a reduction in electron flux to eventually Moderate or background levels. However, there remains some uncertainty regarding the timing of the onset of these coronal hole fast winds.

The MOSWOC REFM forecast indicates a potential reduction in fluence by 30 Dec, but confidence in this scenario is low and assessed as unlikely. MOSWOC REFM recurrence is considered a more likely scenario, with current observed fluence running just below persistence but with a similar profile. As a result, an extended period of Active high-energy electron fluence is expected until the arrival of fast solar wind from CH10/-. At that point, fluence levels are forecast to decline in response to reduced electron flux, potentially dropping below the Active threshold later on Day 3 (31 Dec).