Forecaster summary - Issued 2019-03-29T00:29:22

The high energy flux (greater than 2 MeV) will start at low to background levels, and is then expected to increase moderate to high through tomorrow, with increasingly high peaks of the diurnal cycle occurred through days 3 and 4 (31st and 1st). Therefore the corresponding fluence levels are expected to increase, and are likely to exceed the Active threshold (1e8 integrated pfu) later day 3, then remaining above the Active threshold for day 4. This will be slightly slower compared to the previous rotation of CH92, when it took approximately 2.5 days for the fluence to rise from very low levels (at the time of onset of the HSS) to breach the Active threshold. For this rotation as the high speed stream is slightly slower, having peaked at 537 km/s compared to the previous rotation peak of around 600 km/s, and the associated coronal holes 92 and 96 are slightly smaller and less defined, it is expected that it will take a little longer for the Active fluence level to be breached; either late on day 3 (31st) or through during day 4 (1st). Therefore the gradual increase in fluence levels shown by the Met Office REFM model is considered useful guidance, with the model trying to indicate a sharper increase in fluence during day 3 (31st).