Forecaster summary - Issued 2021-11-20T00:37:36

The high energy electron flux (greater than 2 MeV) has been at mainly moderate levels today (19th). The anticipated onset of CH20/- later on day 1 (20th) is likely to temporarily suppress flux levels before they then begin to rise under HSS influence. This brings an increasing chance of reaching the High threshold (1000 pfu) from day 2 (21st).

The corresponding fluence is likely to have an increasing trend through the period, with an increasing chance of reaching the Active (1e8 integrated flux), on days 3 and 4 (22nd and 23rd). 

The Met Office REFM model shows the fluence following an upward trend, eventually breaching the Active threshold. The overall trend is considered good guidance, however there is uncertainty regarding precisely when Active fluence may be reached, this is more likely as the period progresses once HSS has been established.