Overview
- NOAA’s Space Weather Prediction Center upgraded its outlook on Thursday to a G3 (strong) geomagnetic storm watch for June 4–5 and warned isolated G4 (severe) intervals are possible.
- The alert follows a May 30 CME, a co-rotating interaction region and high-speed stream plus multiple flares and CMEs from June 3 that may arrive in close succession and reinforce one another.
- Forecast timing and intensity remain uncertain because short-term predictions depend on real‑time solar‑wind and magnetic data from the DSCOVR spacecraft about 1 million miles upstream.
- A G3 event (Kp around 7) can push the auroral oval far south, making the northern lights visible across much of Canada and large parts of the northern United States, though short summer nights and moonlight may limit sightings.
- NOAA and national services urge people to monitor live space‑weather feeds and advise operators to check power, satellite and high‑frequency radio systems for possible disturbances during the storm window.