A coronal hole high speed stream (CH HSS) began to rotate into an Earth-connected position midway into the 1 September UTC-day. Last rotation (approximately 27 days ago), this CH HSS was responsible for several days of geomagnetic response no higher than active levels (K4). This time, however, the CH HSS connected well with Earth and solar wind speeds were higher - reaching up to 700 - 800 km/s. The high solar wind speeds and periods of favorable orientation, elicited geomagnetic reaction up to the G1-G2 (Minor-Moderate) storm levels. The CH HSS is still causing solar wind speeds from 550-600 km/s as of 5 Sep, however geomagnetic responses have decreased and more recently ranged from quiet to active. Because of continuing CH HSS effects, periods of active (K4) conditions are still expected on 5 September.
NOAA Scales mini
HF Radio: Weak or minor degradation of HF radio communication on sunlit side, occasional loss of radio contact.
Navigation: Low-frequency navigation signals degraded for brief intervals.
More about the NOAA Space Weather Scales
Navigation: Low-frequency navigation signals degraded for brief intervals.
1 - 4 September Geomagnetic Storming Summary
1 - 4 September Geomagnetic Storming Summary