Forecaster summary - Issued 2018-01-17T00:22:02

Solar wind speeds are currently close to background, suggesting that any increases in high energy (greater than 2MeV) electron flux levels are unlikely during days 1 to 3. with only limited charging of the Van Allen belts occurring. Consequently there is only a low chance of flux values reaching High levels during this period. The high speed stream from coronal hole 61 is then likely to become geoeffective either late on day 3 or early day 4, with an increase to flux levels likely through day 4, and perhaps reaching High levels by the end of the period. Whilst persistence from the previous solar rotation does suggest that this high speed stream is unlikely to show a significant electron response, this is discounted due to some visible dynamic changes having occurred to the coronal hole on this rotation, reducing the reliability of persistence. However this does reduce the confidence in the forecast beyond day 3.

The corresponding 24-hour fluence is therefore expected to remain relatively stable until the end of day 3 as flux levels persist at their current level.  Whilst an increase can then expected during day 4, it remains low confidence as to whether or not this will reach the Active threshold (greater than 1e8 integrated pfu) by the end of the period.