A partial halo Coronal Mass Ejection (CME) produced by the C3.8 solar flare from Region 2816 at 04:35 UTC on April 22 is heading toward Earth and is expected to arrive on April 25. As a result, a G2 – Moderate geomagnetic storming is expected.
This CME has been analyzed multiple times by SWPC forecasters and a best WSA-Enlil model result was determined. This solution indicates an Earth-directed component and arrival of the CME early to mid-day UTC on April 25.
The forecast now calls for likely geomagnetic storm conditions, with the potential to reach G2 – Moderate storm levels, therefore, a G2 geomagnetic storm watch has been issued for April 25.
While forecast confidence in an Earth-directed component is fair, timing and intensity confidence is lower.
Solar wind parameters over the past 24 hours indicated the arrival of a Co-Rotating Interaction Region (CIR) ahead of Coronal Hole High Speed Stream (CH HSS).
The total field increased to a maximum of 11 nT at 21:11 UTC on April 23 while the Bz component ranged from +5/-10 nT. Solar wind speed began to show an increase after 20:55 UTC to near 470 km/s.
Phi angle settled into a mostly negative (towards) solar sector after 08:50 UTC (April 23).
Negative polarity CH HSS influence is expected through April 24, with solar wind speeds expected in the 450 – 550 km/s range. By mid to late April 25, the April 22 CME is expected to arrive, causing another enhancement in solar wind parameters into April 26.
The geomagnetic field over the past 24 hours ranged from quiet to G1 – Minor geomagnetic storming due to onset of CIR/CH HSS effects and is expected to be at unsettled to active levels with a chance for G1 – Minor geomagnetic storm levels on April 24 due to continued CH HSS effects.
G1 – G2 (Minor-Moderate) geomagnetic storm levels are expected around mid to late on April 25 due to the arrival of the aforementioned CME.
Unsettled to active levels are expected on April 26 as CME effects persist.
Featured image credit: SWPC
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