Geomagnetic Storm Watches for 27 & 28 September
A G1 (Minor) geomagnetic storm watch is in effect for 27 September 2017 and a G2 (Moderate) watch is in effect for 28 September, 2017. The watches are in anticipation of likely overall planetary geomagnetic responses to the effects of a recurrent, positive polarity coronal hole high speed stream (CH HSS). The CH HSS is expected to rotate into an Earth-connected position position causing an increase in solar wind speeds that will likely result in G1 level storm periods on 27 September; followed by G2 level storm periods on 28 September. Continue to check our SWPC website for additional updates and forecasts.