Sunspot AR2816 late in the evening of April 19 (11:42 UT), ejected a strong M1 solar flare.
NASA’s Solar Dynamics Observatory has recorded an extreme ultraviolet flare.
This is one of the most powerful outbreaks in a very long period of their complete absence. A pulse of X-rays and ultraviolet radiation from the flare ionized the upper atmosphere of the Earth, causing a blackout of shortwave radio communications over the Pacific Ocean. Mariners and radio amateurs in the area may have noticed unusual propagation conditions below 10 MHz.
It is possible that the explosion also caused a coronal mass ejection (CME) towards the Earth. If so, it will likely arrive on April 22-23, triggering a massive geomagnetic storm.
However, there is still no exact forecast. We need to wait for additional data from SOHO coronagraphs to confirm the direction of the CME ejection towards the Earth.