Forecaster summary - Issued 2019-12-21T00:09:44

The high energy electron flux (greater than 2MeV), as measured by GOES16, is expected to rise over the next few days. The diurnal peak flux may reach High levels today (21st Dec), but is more likely to reach High levels from tomorrow (22nd Dec) onwards. 

During the last rotation it took 5 days from the onset of the high speed stream, for the corresponding 24-hour integrated electron fluence to reach Active levels. This is much slower than the forecast from the Met Office REFM model. Despite these indications from REFM, a slow rise is again preferred, with Active fluence most likely by day 3 (23 Dec)