Space Weather Forecast Headline: Likely Minor-Moderate Geomagnetic Storm into Easter weekend.

Analysis of Space Weather Activity over past 24 hours

Solar Activity: Activity rose to Moderate, with the peak flare observed from the northwest of the Sun at 02/1815UTC.

There are up to eight sunspot regions on the Earth-facing side of the Sun at present, with a ninth passing from view on the western solar horizon. Many of the current regions appeared as simple, symmetric magnetically unipolar groups. The two main exceptions to this were: a group in the south-centre of the Sun, which was stable in terms of its growth trend. Also of note was a group in the northeast, which showed strong proliferation of intermediate spots, with these then migrating apart. Other regions were largely unchanged.

A Coronal Mass Ejection (CME) was seen heading northwest of the Sun-Earth line in imagery during the UTC afternoon of Thursday 02 April. This was inferred as being front-sided, however there was no obvious source region. This should most likely miss Earth but modelling results are awaited. The peak flare of the period was very likely associated with a further CME, with imagery awaited for this event.

Solar Wind / Geomagnetic Activity: The solar wind showed weak CME effects initially, followed by the onset of the fast wind from a coronal hole from 02/0330UTC.

Solar wind speeds started the period level within slightly elevated levels, but then displayed a steady rise to a UTC evening peak of strong levels in the fast wind proper. The number of particles in the solar wind fell over the same interval, while their associated magnetic field peaked mid-period, but started and ended near background. The north-south component of the magnetic field was mainly anti-aligned with Earth's (generally to greater geomagnetic effect).

The net result of the above solar wind measures was for provisionally up to Moderate Geomagnetic Storm G2 Kp indices, peaking in the 15-18UTC interval.

Energetic Particles / Solar Radiation: Solar radiation levels rose from Background from 02/0200UTC, ending the 24 hours at 5pfu, but therefore remaining below the S1/Minor radiation storm threshold (starting at 10pfu).

Four-Day Space Weather Forecast Summary

Solar Activity: Moderate-class flares are likely, with a daily slight chance of strong-class. These probabilities are held constant throughout, with no major arrivals or departures expected in terms of sunspot regions over the four days.

Solar Wind / Geomagnetic Activity: There is one confirmed CME in the forecast - from the 01 April northwestern 'filament eruption' (arc of plasma). A second CME from 02 April is undergoing analysis and is awaited. The sole fast wind of the period (from a coronal hole) is currently in course.

The forecast is of lower than average confidence given the inbound glancing blow from the 01 April CME and unknowns from unassessed CMEs. The priming effect of the non-persistent current fast wind is also unknown, however overall G1-G2 Minor to Moderate geomagnetic storms are likely in the current UTC day, with a slight chance of G3 strong storms should a fuller hit from the CME materialise earlier in the period while the current fast wind remains strong. These risks should recede over the Easter weekend, but note the possibility of a further CME undergoing analysis. The most reliably quiet day of the period should be Easter Monday, 06 April - barring further events.

Energetic Particles / Solar Radiation: Solar radiation shows a chance of rising above the S1/Minor radiation storm threshold, especially when the 01 April CME arrives, with this risk then relaxing over the four-day period - barring new events.