Forecaster summary - Issued 2018-12-30T00:01:05

The high energy (greater than 2MeV) electron flux is now expected to rise above the Active threshold at the peak of the diurnal cycle through the forecast period. The 24-hour fluence level is also expected to be near or exceed the Active threshold at times during the period. The fluence has risen strongly today, but as we are now past the diurnal maximum the rate of increase is likely to slow. It is likely that the Active threshold (1e8 integrated pfu) will be breached some time later on Day 1, or on Day 2, and then continue above Active at times through Days 3 and 4. This is reflected in the REFM forecast which has levels very close to the Active threshold on Days 1 to 3. However, during the previous rotation this coronal hole failed to lead to a rise in the electron fluence and levels remained low, which reduces confidence somewhat. The probabilities given above for breach of the threshold are therefore quite marginal, between 40 and 60 percent.