Forecaster summary - Issued 2021-11-19T00:16:45

The high energy electron flux (greater than 2 MeV) has not reached High (1000 pfu) levels under the influence of the HSS from CH19, despite days of strong or elevated solar winds. Therefore it is now considered that the high energy electron flux is unlikely to exceed the High threshold today or tomorrow, but is likely to breach the High threshold after the next HSS arrives, probably by during day 4 (22nd). During day 3 (21st) geomagnetic activity, associated with the arrival of the HSS, is expected to temporarily supress the electron flux. The corresponding fluence is likely to have an increasing trend, whilst remaining below the Active (1e8 integrated flux). 

The Met Office REFM model shows the fluence remaining below the Active threshold during day one, but then increases the fluence to above Active for days 2 and 3. This is considered to be initially good guidance, before then declining in usefulness.