R1-R2 (Minor-Moderate) radio blackouts have occurred on 4 September, 2017; with NOAA/SWPC Region 2673 the source of the events. RGN 2673 is a magnetically complex and compact sunspot group that has produced numerous C-class flares and occasional M-class flares on 4 September; the largest thus far was an M5 (R2-Moderate) event at 2033 UTC (1633 ET). Sunspot RGN 2674 is not as magnetically complex and has been relatively inactive. However, due to the development of mixed polarities within RGN 2673, its continued growth, and activity trends, the forecast now calls for expected R1-R2 events the remainder of 4 September on into 5 September. Keep checking our SWPC webpage for the latest forecasts and alerts.
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.
R1-R2 Radio Blackouts on 4 September, 2017
R1-R2 Radio Blackouts on 4 September, 2017