Forecaster summary - Issued 2019-12-18T00:02:01

The high energy electron flux (greater than 2MeV), as measured by GOES 16, is expected to be at normal background levels intially. The increase in solar wind speed from coronal hole 92 is likely to give an increase in electron flux over the next few days. The timing of the increase is a little uncertain as the flux took longer to increase on the last rotation than on previous rotations. However it seems likely that there will be an increasing trend during this period, with the diurnal maximum perhaps reaching High levels from Day 1 (18 Dec) but more likely from Day 2 (19 Dec).

The above should result in an increasing likelihood of reaching the Active threshold for 24-hour integrated electron fluence. The REFM model is showing an increasing trend, although it may be slightly underplaying the increase. Reaching the Active threshold is more likely to occur at the end of the period and over the weekend, in line with the increase in probabilities.