NOAA’s Space Weather Prediction Center (SWPC) issued a G3 – Strong Geomagnetic Storm Watch on November 5, forecasting sustained geomagnetic activity between November 6 and 7 and a gradual decrease to G1 – Minor levels by November 8.
The forecast replaces all previous storm watches and follows a period of high solar activity driven by Active Region 4274, currently located in the northeast quadrant and maintaining a beta-gamma-delta magnetic configuration associated with major flaring potential.
Two X-class solar flares (X1.8 and X1.1) erupted on November 4 from Region 4274 and an area just beyond the east limb, producing CMEs largely off the solar limb but with trailing material expected to glance Earth between late November 6 and November 7.
The solar wind is predicted to exceed 600 km/s as CME trailing edges merge with a coronal-hole high-speed stream. Real-time solar wind data from DSCOVR currently show speeds between 340 and 450 km/s and total IMF strength of 3–7 nT with a persistent southward Bz component around −6 nT. A significant increase in both parameters is expected as the CME/CH interaction region arrives.
According to the SWPC and NOAA Ovation-Prime model, the auroral oval is forecast to expand substantially during storm maximums on November 6–7, with the probability of visible aurora as far south as Pennsylvania, Iowa, and Oregon.
Auroral activity will be most intense at latitudes above 50° geomagnetic, including northern U.S. states such as Montana, North Dakota, Minnesota, Wisconsin, Michigan, and northern New York. However, weather conditions and moonlight may affect visibility.
Under G3 – Strong geomagnetic storm conditions, power systems may experience voltage irregularities and occasional false alarms in protective devices. Satellites in low Earth orbit could encounter increased atmospheric drag and surface charging, leading to temporary orientation or telemetry issues.
Navigation systems, particularly GPS, may show intermittent degradation or signal loss, while high-frequency (HF) radio propagation at high latitudes can become unreliable. These effects are expected to remain short-lived and localized, with no indication of widespread infrastructure disruption.
Geomagnetic conditions are expected to subside to unsettled levels (Kp 3–4) by November 8 as solar wind pressure declines. However, Region 4274 remains active and capable of producing additional Earth-directed CMEs as it rotates further westward on the solar disk. SWPC flare probabilities remain elevated at 70% for M-class and 25% for X-class events through November 7.
Due to the flaring potential of the aforementioned regions and their rotation toward a more geoeffective position on the solar disk, additional Earth-directed CMEs are possible in the days ahead. The likelihood of such events will increase as Region 4274 and the adjacent active area move into better magnetic alignment with the Earth–Sun line.