Forecaster summary - Issued 2021-04-19T12:56:04

The high energy electron flux as observed by GOES-16 showed a strong response to the current high speed stream from coronal hole 46, rising rapidly to reach a new diurnal oscillation peaking at High flux.

The continuation of this oscillation seems likely unless there is a significant tail of geomagnetic activity from CH46 when solar wind speeds are lower and the environment is less supportive of maintaining such levels of electrons. Very gradual waning of the current levels is therefore postulated, although this is expected to accelerate significantly upon the arrival of forthcoming coronal hole 47 on day 4 (22nd April).

The effect of CH47 on 24-hour integrated fluence should not manifest itself in the four-day period, and thus fluence levels are expected to remain Active (>1e8 integrated pfu). There is a slight chance of the Very Active (>1e9 integrated pfu) threshold being exceeded.