A G2 – Moderate geomagnetic storm is underway on March 26, influenced by a co-rotating interaction region (CIR) ahead of a high-speed stream (HSS) from a large coronal hole in the southern hemisphere.
The arrival of CIR was felt since late March 25 but solar wind speeds remained below 500 km/s until a sharp increase around 13:30 UTC today. Geomagnetic K-index of 6 (G2 – Moderate geomagnetic storm) threshold was reached at 13:58 UTC.
Under G2 conditions, the area of impact is primarily poleward of 55 degrees Geomagnetic Latitude. Power grid fluctuations are a possibility, with high-latitude power systems potentially experiencing voltage alarms due to induced currents.
In space, satellites may face orientation irregularities, and there is an increased likelihood of drag affecting low Earth-orbit satellites.
HF (high frequency) radio propagation may experience fading at higher latitudes. Additionally, the aurora could be visible as far south as New York, Wisconsin, and Washington state, providing a rare visual treat for observers in these areas.
Solar activity has intensified today, with an M1.0 solar flare from Region 4043 at 08:09 UTC. A Type II radio emission with estiamted velocity of 571 km/s was detected at 09:20 UTC, likely associated with a coronal mass ejection (CME) from beyond the SW limb.
Given the reduced number of regions and their simple magnetic complexity, flare activity is anticipated to remain low with predominantly C-class flares.
There is a 30% chance of isolated M-class (R1-R2, Minor-Moderate) flares through March 26, with the likelihood diminishing as Region 4036 rotates beyond the western limb. The probability of X-class (R3 Strong) flares remains very low, ranging between 1% and 5%, through March 28.
References:
1 Forecast Discussion – SWPC – Issued at 12:30 UTC on March 26, 2025