NOAA forecasters say that G2-class geomagnetic storms are possible on April 25th when a coronal mass ejection (CME) is expected to hit Earth's magnetic field. The CME was hurled in our direction earlier today by a C3.8-class flare from sunspot AR2816 (details below). If the geomagnetic storm occurs as predicted, auroras could dip into northern-tier US states from Maine to Washington. Aurora alerts: SMS Text.

SOLAR TSUNAMI AND CME: Earth-facing sunspot AR2816 exploded this morning, producing a C3.8-class solar flare. A pulse of X-rays and UV radiation ionized the top of Earth's atmosphere, producing a shortwave radio blackout over southeast Asia. Of greater interest, however, is this shadowy wave rippling away from the blast site:

This is a "solar tsunami." It is a wave of hot plasma and magnetism, about 100,000 km tall, racing away from the blast site approximately 250 km/s. Such waves are usually associated with the launch of coronal mass ejections (CMEs)--and indeed, one has been observed.

Coronagraphs onboard the Solar and Heliospheric Observatory (SOHO) detected a CME billowing away from the sun in the hours after the flare. It is faint but definitely Earth-directed:

The initial velocity of the CME was ~760 km/s. Based on its speed and other factors, NOAA forecasters believe that the CME will reach Earth on April 25th, potentially sparking G2-class geomagnetic storms. Aurora alerts: SMS Text.