Forecaster summary - Issued 2020-10-31T00:24:45

The high energy electron flux (greater than 2 MeV), as observed by GOES-16, has persisted at high levels since the 26th (above 1000 pfu), peaking on the 28th and gradually declining since. This high flux would typically be expected to persist mainly at these levels for the rest of the forecast period. However the forecast CME arrival, likely early on the 31st, is expected to impact on the observed electron count at GEO. This will likely cause a sharp dropout in values on arrival, with any recovery after the passing of the CME low in confidence. This means that the main uncertainty in this forecast is the arrival of this CME, and how much of an impact is observed.  

The associated fluence is expected to respond to any dropout that does occur. Currently well above the Active threshold, and with only a gradually declining trend, these fluence values are likely to fall below the Active threshold either late day 1 (31st) or day 2 (1st) depending upon the timing and impact of the expected CME. Fluence values are most likely to remain below the Active threshold thereafter, however there is a chance of Active fluence day 3 or 4 from either a recovering in electron counts, or if the expected CME misses the Earth. If the CME does miss, then REFM is currently giving good guidance, with a gradual reduction in values expected.