Forecaster summary - Issued 2018-03-22T00:17:04

The high energy electron flux (greater than 2MeV) as measured by GOES-15 at GEO was at high levels (above 1000pfu) through the past 24 hours, with a peak flux of 22,000pfu at 20/1940UTC. The flux is likely to remain at mainly high levels throughout the forecast period, but with a gradual overall decline. There will also be some occasional temporary reductions to background or moderate levels during any enhanced geomagnetic activity, with the main risk later on day 3 or early day 4, but with a chance of occurring at any point throughout.

The corresponding 24-hour electron fluence was well above the Active threshold (1e8 integrated pfu) for the past 24 hours, with a slowly rising trend, and peaking at 9.25e8 integrated pfu. This has now started to show some signs of decline, with flux levels having fallen sLightly compared to a similar point on the previous day, fluence levels are currently not expected to exceed the Very Active level (1e9 integrated pfu). These values should now continue slowly declining, perhaps temporarily falling below the 1e8 threshold on day 3 and early day 4. However the arrival of the high speed stream from coronal hole 82 could lead to further charging of the Van Allen belts by the end of day 4, and perhaps a return of Active fluence levels.