Solar activity reached moderate levels on July 30 after Region 4492 (N15W82, Hax/alpha) produced a long-duration M1.9/Sf at 17L00 UTC. Coinciding with the flare was an approximately eight-degree-long filament eruption, centered near N20W67.
Additionally, two Type II radio sweeps were observed — the first at 16:27 UTC, with an estimated velocity of 853 km/s, and the second at 16:45 UTC, estimated velocity 1 681 km/s. Other radio events included a Type IV sweep at 16:31 UTC, and a 17-minute-long Tenflare (190 sfu) that peaked at 16:43 UTC.
The greater-than-10 MeV proton flux crossed the S1 – Minor solar radiation storm threshold at 18:45 UTC on July 30 and reached a peak of 18 pfu at 20:55 UTC. The flux fell below the S1 threshold by 00:30 UTC on July 31 and passed the threshold again at 13:27 UTC.
SWPC said the proton enhancements were likely associated with the M1.9 flare from Region 4492. The agency retained a chance of renewed S1 conditions on July 31 and August 1, while the greater-than-2 MeV electron flux was expected to remain at normal to moderate levels through August 2.
A partial-halo CME appeared in GOES CCOR2 coronagraph imagery beginning at 17:15 UTC, while STEREO COR2 imagery showed a full-halo signature beginning at 16:53 UTC. WSA-Enlil model runs placed a possible arrival at Earth early on August 2.
Solar wind parameters remained at nominal levels in 24 hours to 12:30 UTC today. Total magnetic field strength remained below 5 nT, solar wind speed was mainly between 300 and 330 km/s, and the phi angle was predominantly oriented in the positive solar sector.
SWPC said a diminishing chance of disturbed solar wind conditions remained on July 31 as CMEs launched on July 26 and 27 could still graze Earth. Another disturbance is possible on August 1 from a CME that left the Sun late on July 27, combined with weak influence from a coronal hole high speed stream. A more pronounced enhancement in solar wind parameters is likely early on August 2 as the July 30 CME passes by Earth.
Quiet to unsettled geomagnetic conditions are forecast through August 1, with isolated active periods possible under the combined influence of a weak positive polarity coronal hole high speed stream and glancing or relatively weak effects from the July 26 and 27 CMEs.
SWPC expects G1-G2 geomagnetic storm levels on August 2 due to the anticipated arrival of the July 30 CME. Under G2 geomagnetic storm conditions, high-latitude power systems may experience voltage alarms, while prolonged storming can affect transformers.
Spacecraft operators may need to make orientation corrections, and increased drag can affect satellites in low Earth orbit. High-frequency radio propagation can fade at higher latitudes, and aurora may become visible as far south as New York and Idaho in the United States under favorable conditions.
Solar activity is expected to remain low through August 2, with a chance of M-class flares and associated R1-R2 (Minor-Moderate) radio blackouts.
References:
1 Forecast Discussion – NOAA/SWPC – Issued at 12:30 UTC on July 31, 2026