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Multiple coronal mass ejections (CMEs) linked to repeated eruptions from Active Region 4479 are forecast to reach Earth in stages from July 3 through 6. NOAA\u2019s Space Weather Prediction Center (SWPC) forecasts G1 \u2013 Minor to G2 \u2013 Moderate geomagnetic storm conditions from July 3 into 4 from the CME associated with the June 30 X1.1 flare, while later CME arrivals still remain under model assessment.<\/p>\n
Space weather physicist Dr. Tamitha Skov described the activity as a \u201cMachine-Gun Sun,\u201d saying more than five solar storms are headed toward Earth and that the first could arrive before 12:00 UTC on July 3. Skov said geomagnetic conditions above G2 would depend on the magnetic orientation of the arriving CMEs.<\/p>\n
NASA\u2019s Community Coordinated Modeling Center (CCMC) CME Scoreboard listed six active CME entries on July 2, with modeled shock-arrival estimates spanning July 3 through 6. The entries include eruptions associated with M1.4, X1.1, M1.0, M3.5, and M4.2 flares, as well as a June 30 eruption from or near the same active region complex.<\/p>\n
The earliest modeled arrivals are related to a CME associated with the M1.4 flare at 21:40 UTC on June 29 and the full-halo CME produced by the X1.1 flare at 20:50 UTC on June 30.<\/p>\n
CCMC\u2019s model entries placed their median arrival times at 11:00 UTC and 05:39 UTC on July 3, respectively. NOAA\u2019s official July 2 forecast expects the June 30 CME early on July 3 and calls for G1\u2013G2 geomagnetic storm conditions through July 4.<\/p>\n
A further CME linked to an eruption beginning near 13:30 UTC on June 30 has a modeled arrival at 18:00 UTC on July 5. CCMC also lists a CME associated with an M3.5 flare from Region 4479 at 19:43 UTC on July 1, with an average arrival estimate near 11:59 UTC on July 5.<\/p>\n
A faint CME associated by CCMC with an M1.0 flare at 11:25 UTC on July 1 has a median arrival estimate near 21:50 UTC on July 5. However, an OSPREI model run for the same entry places the arrival at 07:41 UTC on July 6.<\/p>\n
SWPC\u2019s Forecast Discussion issued at 12:30 UTC on July 2 includes a slow-moving CME with an Earth-directed component after an M1.3 flare at 10:08 UTC on July 1. The agency associated a later CME, first observed in coronagraph imagery near 02:36 UTC on July 2, and presumed source to a long-duration M4.2 flare from Region 4479.<\/p>\n
SWPC modeling forecasts that the later CME will catch up to and overtake the earlier Earth-directed CME, with arrival expected from late July 5 to early July 6.<\/p>\n
CCMC\u2019s M4.2-associated CME entry used an arrival estimate of 02:00 UTC on July 5, with a seven-hour uncertainty range on either side and a modeled maximum Kp range of 4\u20136.<\/p>\n
The NOAA and CCMC records use different flare associations for closely timed July 1 activity. SWPC linked its slow Earth-directed CME to an M1.3 flare at 10:08 UTC, while CCMC listed a separate faint CME as most likely associated with an M1.0 flare at 11:25 UTC.<\/p>\n
Geomagnetic conditions remained quiet to unsettled before the July 3 forecast window, with the highest observed three-hour Kp during the preceding 24 hours at 3, below NOAA storm levels.<\/p>\n
NOAA\u2019s active G2 Geomagnetic Storm Watch, issued at 09:35 UTC on July 2 and superseding all prior watches, forecasts moderate geomagnetic storm conditions on July 3 and 4.<\/p>\n
Potential effects are expected mainly poleward of 55\u00b0 geomagnetic latitude and include power-grid fluctuations, voltage alarms in high-latitude systems, satellite orientation irregularities and increased drag on low-Earth-orbit satellites, degraded high-frequency radio propagation at high latitudes, and aurora as far south as New York, Wisconsin, and Washington state.<\/p>\n
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