Solar activity has been at moderate levels for the past 24 hours. Region 1302 (N13E23) produced the largest event of the period, a M2 x-ray flare at 1446Z. Region 1301 (N17W23) and Region 1303 (S28W90) also produced several low level C-class events.

Solar activity is expected to remain at moderate levels on day one (27 September). Low to moderate levels are expected on day two (28 September) and predominantly low levels are expected on day three (29 September). Region 1302 remains the most active Region on the disk but has only produced one M-class event over the past 24 hours.

The geomagnetic field has been at major storm levels for the past 24 hours. A CME, observed leaving the solar disk on 24 September, arrived at Earth on 26/1237Z. Indicating the arrival of the CME, a 45 nT sudden impulse was observed by the Boulder magnetometer. As the CME progressed, measurements by the ACE spacecraft showed the total IMF reaching a peak of 33 nT, with the negative (Southward Component, Bz) reaching a maximum of-31 nT. Solar wind speeds increased from around 350 km/s to 650 km/s. During the CME passage, both GOES 13 and GOES 15 spacecraft showed clear magnetopause crossings. The greater than 10 MeV proton event, that began at 23/2255Z, reached up to 35.7 pfu at 26/1115Z, and continues to remain above the 10 pfu threshold.

The geomagnetic field is expected to be at unsettled to active levels for the next two days (27-28 September) with a slight chance for minor storm levels, due to the trailing effects of the latest CME and the possible arrival of a second CME. A return to predominately quiet levels is expected on day three (29 September).

  Observed       26 Sep 148
  Predicted   27 Sep-29 Sep  145/145/140
  90 Day Mean        26 Sep 108

  Observed Afr/Ap 25 Sep  004/004
  Estimated     Afr/Ap 26 Sep  027/060
  Predicted    Afr/Ap 27 Sep-29 Sep  012/010-010/015-005/005