Forecaster summary - Issued 2021-12-05T00:21:24

The high energy electron flux (greater than 2 MeV) as observed by GOES-16 showed a sharp drop from the peak on Friday during the UTC evening. This may have been a result of some radiation belt compression with the arrival of the fast wind of CH27/CH28. Wind speeds are already dropping, and it is likely that we will see a recovery in flux values back to High levels during day 1, perhaps with a slight increase as further charging may have occurred.

The associated 24 hour electron fluence is currently just below the Active (greater than 1e8 integrated pfu) threshold due to the recent drop out in flux levels. Confidence for Active fluence is a little low given the recent sharp drop in flux values, but the most likely scenario is a return to Active fluence during days 1 and 2 (5th and 6th), then probably remaining above through Days 3 and 4 (7th and 8th Dec). REFM is suggesting a downward trend but is considered to be reducing values too quickly.