Forecaster summary - Issued 2020-03-16T00:00:31

The current high energy electron flux diurnal oscillation is mostly confined to Normal Background values, and this is expected to continue until at least midweek. The forecast onset of a coronal hole on Thursday 19 March is relatively low confidence in itself due to being a non-persistent feature, however this assumes lower speeds than seen emanating from the southern crown on last rotation, where Kp4 and 500km/s were observed. Even a speed as high as 450km/s still puts geomagnetic effects into day four, and this is thought to be on the upper end of possibilities from CH27 given is frail appearance.

All considered, Thursday should see the peak risk of Active electron fluence in the four days, however even this is rated a Slight Chance for being too early for the fluence peak, with Friday probably seeing higher counts. Even on Friday, chances are not thought to be significantly higher due to the expected lower intensity of coronal hole influence on this pass.

On the last full rotation, activity in this upcoming four-day period was the only geomagnetism that proved sufficient to give Active fluence (after a very slow rise to peak on 23 February). For reasons discussed, this is unlikely to be repeated, but counts should still rise to a peak around the end of this week.