Forecaster summary - Issued 2021-12-26T12:44:42

The high energy (greater than 2MeV) electron flux, as observed by GOES-16, has been mainly moderate. Peaks at high levels are likely at diurnal max, however the arrival of the fast wind of coronal hole 37 on days 2 or 3 (27 or 28 Dec), and subsequently coronal holes 38 and 39  on days 3 or 4 (28 or 29 Dec), could drop observed flux levels to background for a time as the radiation belts compress. A re-enhancement could then subsequently occur as any compression of the radiation belts recedes. Moderate to High levels are then possible day 4.

The associated 24 hour fluence is likely to persist below the Active threshold. This is supported by REFM which is currently giving a good guide. Fluence levels are expected to rise from day 3 onward, in response to the increased flux, with a slight chance of rising above the Active threshold during day 4.